tag:theconversation.com,2011:/au/topics/cochrane-review-16402/articlesCochrane review – The Conversation2023-09-25T01:41:27Ztag:theconversation.com,2011:article/2131452023-09-25T01:41:27Z2023-09-25T01:41:27ZDo blue-light glasses really work? Can they reduce eye strain or help me sleep?<figure><img src="https://images.theconversation.com/files/549203/original/file-20230919-25-ucj5dq.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/asian-womans-eyes-stress-blue-blocking-1391138681">Shutterstock</a></span></figcaption></figure><p>Blue-light glasses are said to <a href="https://www.baxterblue.com.au/collections/blue-light-glasses">reduce eye strain</a> when using <a href="https://www.blockbluelight.com.au/collections/computer-glasses">computers</a>, improve your <a href="https://www.ocushield.com/products/anti-blue-light-glasses">sleep</a> and protect your eye health. You can buy them yourself or your optometrist can prescribe them.</p>
<p>But <a href="https://mivision.com.au/2019/03/debate-continues-over-blue-blocking-lenses/">do they work</a>? Or could they do you harm?</p>
<p>We <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013244.pub2/full">reviewed</a> the evidence. Here’s what we found.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-will-i-damage-my-eyes-if-i-dont-wear-sunglasses-68582">Health Check: will I damage my eyes if I don't wear sunglasses?</a>
</strong>
</em>
</p>
<hr>
<h2>What are they?</h2>
<p>Blue-light glasses, blue light-filtering lenses or blue-blocking lenses are different terms used to describe lenses that reduce the amount of short-wavelength visible (blue) light reaching the eyes. </p>
<p>Most of these lenses prescribed by an optometrist decrease blue light transmission by <a href="https://onlinelibrary.wiley.com/doi/10.1111/opo.12615">10-25%</a>. Standard (clear) lenses do not filter blue light.</p>
<p>A wide variety of lens products are available. A filter can be added to prescription or non-prescription lenses. They are widely marketed and are becoming <a href="https://onlinelibrary.wiley.com/doi/10.1111/opo.12615">increasingly popular</a>.</p>
<p>There’s often an added cost, which depends on the specific product. So, is the extra expense worth it?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-eye-disorders-may-have-influenced-the-work-of-famous-painters-92830">How eye disorders may have influenced the work of famous painters</a>
</strong>
</em>
</p>
<hr>
<h2>Blue light is all around us</h2>
<p>Outdoors, sunlight is the main source of blue light. Indoors, light sources – such as light-emitting diodes (LEDs) and the screens of digital devices – emit varying degrees of blue light. </p>
<p>The amount of blue light emitted from artificial light sources is much lower than from the Sun. Nevertheless, artificial light sources are all around us, at home and at work, and we can spend a lot of our time inside.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Blue light-filtering lenses block some blue light from screens from reaching the eye" src="https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/549210/original/file-20230920-16-tsb23b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Screens emit blue light. The lenses are designed to reduce the amount of blue light that reaches the eye.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/blue-light-blocking-ray-filter-lens-2286229107">Shutterstock</a></span>
</figcaption>
</figure>
<p>Our research team at the University of Melbourne, along with collaborators from Monash University and City, University London, sought to see if the best available evidence supports using blue light-filtering glasses, or if they could do you any harm. So we conducted a <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013244.pub2/full">systematic review</a> to bring together and evaluate all the relevant studies. </p>
<p>We included all randomised controlled trials (clinical studies designed to test the effects of interventions) that evaluated blue light-filtering lenses in adults. We identified 17 eligible trials from six countries, involving a total of 619 adults.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/does-my-treatment-work-how-major-medical-reviews-can-be-gold-standard-evidence-yet-flawed-205014">Does my treatment work? How major medical reviews can be 'gold standard' evidence, yet flawed</a>
</strong>
</em>
</p>
<hr>
<h2>Do they reduce eye strain?</h2>
<p>We found no benefit of using blue light-filtering lenses, over standard (clear) lenses, to reduce eye strain with computer use. </p>
<p>This conclusion was based on consistent findings from three studies that evaluated effects on eye strain over time periods ranging from two hours to five days.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/screentime-can-make-you-feel-sick-here-are-ways-to-manage-cybersickness-163851">Screentime can make you feel sick – here are ways to manage cybersickness</a>
</strong>
</em>
</p>
<hr>
<h2>Do they help you sleep?</h2>
<p>Possible effects on sleep were uncertain. Six studies evaluated whether wearing blue-light filtering lenses before bedtime could improve sleep quality, and the findings were mixed. </p>
<p>These studies involved people with a diverse range of medical conditions, including insomnia and bipolar disorder. Healthy adults were not included in the studies. So we do not yet know whether these lenses affect sleep quality in the general population.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1678293771539161089"}"></div></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/booting-up-or-powering-down-how-e-readers-affect-your-sleep-36145">Booting up or powering down: how e-readers affect your sleep</a>
</strong>
</em>
</p>
<hr>
<h2>Do they boost your eye health?</h2>
<p>We did not find any clinical evidence to support using blue-light filtering lenses to protect the macula (the region of the retina that controls high-detailed, central vision). </p>
<p>None of the studies evaluated this.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/macular-diseases-cause-blindness-and-treatment-costs-millions-here-is-how-to-look-after-yours-196796">Macular diseases cause blindness and treatment costs millions. Here is how to look after yours</a>
</strong>
</em>
</p>
<hr>
<h2>Could they do harm? How about causing headaches?</h2>
<p>We could not draw clear conclusions on whether there might be harms from wearing blue light-filtering lenses, compared with standard (non blue-light filtering) lenses. </p>
<p>Some studies described how study participants had headaches, lowered mood and discomfort from wearing the glasses. However, people using glasses with standard lenses reported similar effects.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-what-causes-headaches-42254">Health Check: what causes headaches?</a>
</strong>
</em>
</p>
<hr>
<h2>What about other benefits or harms?</h2>
<p>There are some important general considerations when interpreting our findings. </p>
<p>First, most of the studies were for a relatively short period of time, which limited our ability to consider longer-term effects on vision, sleep quality and eye health. </p>
<p>Second, the review evaluated effects in adults. We don’t yet know if the effects are different for children.</p>
<p>Finally, we could not draw conclusions about the possible effects of blue light-filtering lenses on many vision and eye health measures, including colour vision, as the studies did not evaluate these.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-are-people-colour-blind-107599">Curious Kids: why are people colour blind?</a>
</strong>
</em>
</p>
<hr>
<h2>In a nutshell</h2>
<p>Overall, based on relatively limited published clinical data, our review does not support using blue-light filtering lenses to reduce eye strain with digital device use. It is unclear whether these lenses affect vision quality or sleep, and no conclusions can be drawn about any potential effects on the health of the retina. </p>
<p>High-quality research is needed to answer these questions, as well as whether the effectiveness and safety of these lenses varies in people of different ages and health status.</p>
<p>If you have eye strain, or other eye or vision concerns, discuss this with your optometrist. They can perform a thorough examination of your eye health and vision, and discuss any relevant treatment options.</p><img src="https://counter.theconversation.com/content/213145/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>In the past three years, Laura Downie's research laboratory at the University of Melbourne has received funding from Alcon Laboratories, Azura Ophthalmics, CooperVision and Novartis for clinical research studies unrelated to this article. She is affiliated with the Tear Film and Ocular Surface Society, as a global ambassador.</span></em></p>They’re heavily promoted. Your optometrist may even prescribe them. But when we looked at the evidence, this is what we found.Laura Downie, Associate Professor in Optometry and Vision Sciences, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2028442023-06-07T02:23:49Z2023-06-07T02:23:49ZHow to treat jellyfish stings (hint: urine not recommended)<figure><img src="https://images.theconversation.com/files/530469/original/file-20230607-30115-psgkb.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C667&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/box-jelly-fish-photographed-aquarium-68332459">Shutterstock</a></span></figcaption></figure><p>If you have been stung by a jellyfish at the beach, you’ll know how painful and unpleasant it can be. But how best to treat jellyfish stings has been debated over the years.</p>
<p>Is it best to use hot water or an ice pack? How about pouring on vinegar or rubbing with sand? Then there’s the popular myth about urinating on your leg, which health professionals have <a href="https://www.scientificamerican.com/article/fact-or-fiction-urinating/#:%7E:text=Back%20in%201997%20all%20the,the%20treatment%20and%20it%20worked.">debunked</a> <a href="https://health.clevelandclinic.org/pee-jellyfish-sting/">many times</a> but seems to resurface regardless.</p>
<p>We looked at the evidence for popular treatments and have <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD009688.pub3/full">just published</a> our analysis in a Cochrane review. This is what we found.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-we-swim-in-the-ocean-we-enter-another-animals-home-heres-how-to-keep-us-all-safe-193457">When we swim in the ocean, we enter another animal's home. Here's how to keep us all safe</a>
</strong>
</em>
</p>
<hr>
<h2>Why do jellyfish stings hurt so much?</h2>
<p>Jellyfish are common in coastal regions around the world. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Warning sign for marine stingers" src="https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524541/original/file-20230505-29-u5skut.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Watch out, jellyfish about.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/yellow-black-warning-sign-dangerous-marine-168106508">Shutterstock</a></span>
</figcaption>
</figure>
<p>They have tentacles covered with tiny stinging cells called nematocysts. When these cells touch your skin, they release venom that can cause burning, redness, swelling and sometimes more serious reactions, such as heart issues.</p>
<p>Fortunately, most jellyfish stings are not life-threatening. Symptoms differ depending on the species. And the best treatment for one species is not always the best for another.</p>
<p>By knowing which treatment works and which doesn’t, you can reduce your discomfort and avoid complications.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-to-avoid-a-bluebottle-sting-heres-how-to-predict-which-beach-theyll-land-on-179947">Want to avoid a bluebottle sting? Here's how to predict which beach they'll land on</a>
</strong>
</em>
</p>
<hr>
<h2>What we did</h2>
<p>We found nine trials involving treatments for two types of jellyfish:</p>
<ul>
<li><p><strong>bluebottles</strong> or Portuguese man o’ war (<em>Physalia</em>)</p></li>
<li><p><strong>box jellyfish</strong> (<em>Cubozoa</em>), which are considered the most dangerous jellyfish. Some box jellyfish can cause Irukandji syndrome (a condition that may lead to severe pain, heart problems, and very occasionally death).</p></li>
</ul>
<p>These trials, involving 574 people, tested various treatments such as vinegar, hot water, ice packs, isopropyl alcohol, methylated spirits, ammonia and sodium bicarbonate.</p>
<p>The trials also looked at Adolph’s meat tenderiser (a powder thought to break down proteins) and Sting Aid (an over-the-counter treatment thought to help ease pain after a variety of stings).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/welcome-to-australia-a-land-of-creatures-out-to-kill-you-maybe-71490">Welcome to Australia, a land of creatures out to kill you... maybe</a>
</strong>
</em>
</p>
<hr>
<h2>So what works?</h2>
<p>Regardless of the jellyfish species, it’s reasonable to first remove any visible tentacles with tweezers or a gloved hand. What to do next depends on the species.</p>
<p><strong>For bluebottles, try heat</strong></p>
<p>The data in our included studies provides what’s described as low-certainty evidence for soaking the affected area in water about 45°C to ease the pain. This is thought to denature the venom protein. At the beach, you could apply a heat pack or take a hot shower.</p>
<p>There was not enough evidence to show whether other treatments, such as ice packs, were effective for bluebottle stings.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C648&q=45&auto=format&w=1000&fit=clip"><img alt="Bluebottle on sandy beach" src="https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C648&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524542/original/file-20230505-27-3vrruw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stung by a bluebottle? Try warm water or a heat pack.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bluebottle-portuguese-man-o-war-on-413370460">Shutterstock</a></span>
</figcaption>
</figure>
<p><strong>For box jellyfish, try vinegar</strong></p>
<p>For box jellyfish stings, the evidence was more limited. Our review did not find sufficient evidence to support <a href="https://resus.org.au/download/guideline-9-4-5-jellyfish-stings-july-2010-43-kib/?wpdmdl=13756&masterkey">current</a> <a href="http://www.ilsf.org/wp-content/uploads/2012/07/MPS-05%20Envenomation.doc">recommendations</a> to apply vinegar to inactivate the nematocysts.</p>
<p>Nevertheless, it’s reasonable to try vinegar. That’s because <a href="https://onlinelibrary.wiley.com/doi/abs/10.5694/j.1326-5377.1980.tb134566.x">evidence</a> not considered as part of our review shows vinegar inactivates nematocysts when tested in the laboratory.</p>
<h2>When to seek medical care</h2>
<p>Most symptoms can be managed at the beach or at home. But always seek medical attention if you or the person you’re looking after has symptoms such as:</p>
<ul>
<li><p>difficulty breathing</p></li>
<li><p>chest pain</p></li>
<li><p>nausea</p></li>
<li><p>vomiting</p></li>
<li><p>weakness, or </p></li>
<li><p>drowsiness.</p></li>
</ul>
<p>Such severe symptoms mean monitoring and treatment in hospital may be needed. If the person stops breathing or has a heart attack, they need immediate basic life support.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-cases-of-cardiac-arrest-time-is-everything-community-responders-can-save-lives-126491">In cases of cardiac arrest, time is everything. Community responders can save lives</a>
</strong>
</em>
</p>
<hr>
<h2>What not to do</h2>
<p>Do not rub or scrape the area with sand or a towel because this might cause more nematocysts to release their venom.</p>
<p>When it comes to treatments, our review found some may be harmful or ineffective, so should be avoided. </p>
<p>These included ammonia, methylated spirits and fresh water, as they may cause burns on the skin or trigger more venom to be released from nematocysts. </p>
<p>Avoid pressure immobilisation bandaging (wrapping a bandage tightly around the limb) as this may also trigger more venom release from nematocysts. </p>
<p>We found vinegar, sodium bicarbonate, Sting Aid or meat tenderiser have no proven benefit and may cause irritation or infection.</p>
<p>Perhaps not surprisingly, there were no published trials looking at the effectiveness of urine as a treatment and so it’s not recommended.</p>
<h2>Prevention is best</h2>
<p>Remember, prevention is better than cure. Keep an eye on safety announcements from lifeguards, monitor the water for jellyfish and wear protective clothing to prevent stings where possible.</p><img src="https://counter.theconversation.com/content/202844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Hot water, cold water, rubbing with sand? What our new review says works best to treat jellyfish stings.Richard McGee, Senior lecturer in Paediatrics, University of NewcastleMichelle Welsford, Professor and Director of the Division of Emergency Medicine , McMaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2050142023-05-22T20:06:36Z2023-05-22T20:06:36ZDoes my treatment work? How major medical reviews can be ‘gold standard’ evidence, yet flawed<figure><img src="https://images.theconversation.com/files/525758/original/file-20230512-37784-bjz76q.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C667&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/stack-paper-files-565403764">Shutterstock</a></span></figcaption></figure><p>Medical decision-making is complex. There are often hundreds, if not thousands, of published studies that may impact how to manage your medical condition.</p>
<p>Some studies look at which drug is best in a particular situation, or whether pain is better treated by, say, avoiding exercise or seeing a physio for therapeutic massage.</p>
<p>In this morass of difficult choices, <a href="https://community.cochrane.org">Cochrane reviews</a> stand out as internationally trusted and <a href="https://www.cochrane.org/about-us/our-funders-and-partners">independent</a>. They are considered the “gold standard” in evidence-based medicine.</p>
<p>They involve teams of researchers looking through all the published academic research on a topic to produce an overall answer on what the best evidence says about different treatments.</p>
<p>However, Cochrane has recently <a href="https://theconversation.com/yes-masks-reduce-the-risk-of-spreading-covid-despite-a-review-saying-they-dont-198992">come under fire</a> after a controversial review that looked at whether wearing masks in the community during COVID worked to reduce the spread of respiratory viruses.</p>
<p>Studies like this can <a href="https://www.mdlinx.com/article/cochrane-reviews-controversy-are-the-concerns-valid/7tjNVFB6sLR2l9VoaXqQDc">raise the question</a> of how useful Cochrane reviews are, particularly for the general public.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1636442499228094464"}"></div></p>
<h2>Issues with evidence-based medicine</h2>
<p>As with any research process, Cochrane reviews are not perfect. And they cannot answer all medical questions.</p>
<p>The entire process – from gathering data based primarily on randomised clinical trials, to reviewing that data and coming to some conclusion about the evidence – was mostly developed in the context of clinical interventions. <a href="https://theconversation.com/randomised-control-trials-what-makes-them-the-gold-standard-in-medical-research-78913">Randomised trials</a> are a type of medical study where people are given treatments in a controlled, random way, giving a robust estimate of whether the treatment works for the condition that’s being studied.</p>
<p>People regularly question whether this “gold standard” framework deals well with things other than surgery, drugs and the like. </p>
<p>For example, take the mask review mentioned above. <a href="https://theconversation.com/yes-masks-reduce-the-risk-of-spreading-covid-despite-a-review-saying-they-dont-198992">Much of the criticism</a> was focused not on the specifics of the included papers, but on the general idea of whether randomised clinical trials are an appropriate way to measure the impact of masks on respiratory disease. </p>
<p>What is the “gold standard” if randomised trials are impossible, unethical, or otherwise inappropriate? For example, if an intervention like vaccination is already proven effective, you can’t ethically randomise people into a group that doesn’t get the treatment.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/yes-masks-reduce-the-risk-of-spreading-covid-despite-a-review-saying-they-dont-198992">Yes, masks reduce the risk of spreading COVID, despite a review saying they don't</a>
</strong>
</em>
</p>
<hr>
<p>This gets at the underlying question of what a Cochrane review is actually there to do. The key aim of aggregating research this way is to filter out the noise and provide the most accurate data on a specific question.</p>
<p>Sometimes, the most honest answer is that we just don’t have enough evidence to make a conclusion.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C998%2C561&q=45&auto=format&w=1000&fit=clip"><img alt="Doctor in white coat, stethoscope around neck, taking notes from laptop" src="https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C998%2C561&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525571/original/file-20230511-15-c6zxpk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sometimes, there is evidence, but not from randomised clinical trials.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/crop-close-indian-woman-doctor-white-2078659765">Shutterstock</a></span>
</figcaption>
</figure>
<p>In other cases, there is evidence, but not from randomised clinical trials. Then the debate becomes about how much weight to give this evidence, whether and how to include it, and how to draw conclusions based on this data. </p>
<p>This may seem arbitrary, but there are good reasons to be wary of findings based only on observational research. A systematic review of observational trials of hormone replacement therapy led to widespread use in the late 90s for preventative health, until randomised trials <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev.publhealth.26.021304.144637">showed</a> the therapy had little to no benefit. </p>
<p>This isn’t actually a new problem. Indeed, it’s something Cochrane has been <a href="https://training.cochrane.org/handbook/current/chapter-24">grappling with for years</a>.</p>
<p>For example, <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010216.pub7/full">a recent Cochrane review</a> into vaping to help people quit smoking included quite a few non-randomised trials. These were not given the same weight as randomised research, but did provide support for the central finding of the review.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/controlled-experiments-wont-tell-us-which-indigenous-health-programs-are-working-74618">Controlled experiments won't tell us which Indigenous health programs are working</a>
</strong>
</em>
</p>
<hr>
<h2>Cochrane is OK about being criticised …</h2>
<p>There have been many issues raised with Cochrane teams over the years. This includes <a href="https://www.sciencedirect.com/science/article/pii/S0895435621002778#!">problems</a> with how reviewers <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0096920">rate trials</a> included in the reviews.</p>
<p>However, the organisation is famously transparent. If you have an issue with a particular review, you can post your comments publicly. <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD015017.pub3/read-comments">I did this</a>, sharing my concerns about a review on using the drug ivermectin to treat COVID.</p>
<p>Cochrane is also good at incorporating criticism. It even has <a href="https://community.cochrane.org/news/prizes-and-awards/bill-silverman-prize">a prize</a> for the best criticism of its work.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-government-says-ndis-supports-should-be-evidence-based-but-can-they-be-204763">The government says NDIS supports should be 'evidence-based' – but can they be?</a>
</strong>
</em>
</p>
<hr>
<h2>… even if reviews take time</h2>
<p>There’s a reason so many experts trust Cochrane. The occasional controversy aside, Cochrane reviews are generally the most detailed and rigorous summary of the evidence on any question you can find. </p>
<p>This attention to detail comes at a cost. Cochrane reviews are often the final word on a subject, not just because they are so robust, but because they take a <a href="https://www.mdlinx.com/article/cochrane-reviews-controversy-are-the-concerns-valid/7tjNVFB6sLR2l9VoaXqQDc">very long time</a> to come out.</p>
<p>Cochrane aims to publish reviews within two years. But more than half take <a href="https://pubmed.ncbi.nlm.nih.gov/32413390/">longer</a> to complete. Cochrane reviews are also meant to be updated regularly, but many have not been updated for <a href="https://europepmc.org/article/med/34427395">more than five years</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/clinical-trials-are-useful-heres-how-we-can-ensure-they-stay-so-16113">Clinical trials are useful – here's how we can ensure they stay so</a>
</strong>
</em>
</p>
<hr>
<h2>In a nutshell</h2>
<p>Cochrane reviews can be flawed, cannot answer all medical questions and, while comprehensive, can take long to complete.</p>
<p>But there’s a reason that these reviews are considered the gold standard in medical research. They are detailed, lengthy, and very impressive pieces of work. </p>
<p>With <a href="https://www.cochranelibrary.com/cdsr/reviews">more than 9,000</a> Cochrane reviews so far, these are still usually the best evidence we have to answer a range of medical questions.</p><img src="https://counter.theconversation.com/content/205014/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>I have previously worked with several members of Cochrane Australia on unaffiliated projects.</span></em></p>Major reviews of medical evidence, known as Cochrane reviews, have come under fire. But is that fair?Gideon Meyerowitz-Katz, PhD Student/Epidemiologist, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1989922023-02-06T19:04:54Z2023-02-06T19:04:54ZYes, masks reduce the risk of spreading COVID, despite a review saying they don’t<figure><img src="https://images.theconversation.com/files/508261/original/file-20230206-504-kijojf.jpg?ixlib=rb-1.1.0&rect=0%2C68%2C4593%2C2984&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.pexels.com/photo/calm-black-woman-with-coffee-wearing-medical-mask-standing-in-metro-6280959/">Pexels/Uriel Mont</a></span></figcaption></figure><p>The question of whether and to what extent face masks work to prevent respiratory infections such as COVID and influenza has split the scientific community for <a href="https://www.baltimoresun.com/news/bs-xpm-2007-03-06-0703060040-story.html">decades</a>. </p>
<p>Although there is strong evidence face masks <a href="https://www.sciencedirect.com/science/article/pii/S0020748920301139?via%3Dihub">significantly reduce transmission of such infections</a> both in health-care settings and in the community, some experts do not agree. </p>
<p>An updated <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub6/full">Cochrane Review</a> published last week is the latest to suggest face masks don’t work in the community. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1620311528523304960"}"></div></p>
<p>However there are problems with the review’s methodology and its underpinning assumptions about transmission. </p>
<p>The Cochrane Review combined randomised controlled trials (RCTs) using <a href="https://ebn.bmj.com/content/16/1/3">meta-analysis</a>. RCTs test an intervention in one group and compare it with a “control” group that doesn’t receive the intervention or receives a different intervention. A meta-analysis pools the results of multiple studies. </p>
<p>This approach assumes (a) RCTs are the “best” evidence and (b) combining results from multiple RCTs will give you an average “effect size”.</p>
<p>But RCTs are only the undisputed gold standard for certain <em>kinds</em> of questions. For other questions, a mix of study designs is better. And RCTs should be combined in a meta-analysis <em>only</em> if they are all addressing the same research question in the same way. </p>
<p>Here are some reasons why the conclusions of this Cochrane Review are misleading. </p>
<h2>It didn’t consider how COVID spreads and how masks work</h2>
<p>COVID, along with influenza and many other respiratory diseases, is transmitted primarily <a href="https://theconversation.com/covid-how-the-disease-moves-through-the-air-173490">through the air</a>. </p>
<p>Respirators (such as N95s) are designed and regulated to prevent airborne infections by fitting <a href="https://theconversation.com/high-filtration-masks-only-work-when-they-fit-so-we-created-a-new-way-to-test-if-they-do-155987">closely to the face</a> to prevent air leakage and by filtering out 95% or more of potential infectious particles. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/high-filtration-masks-only-work-when-they-fit-so-we-created-a-new-way-to-test-if-they-do-155987">High-filtration masks only work when they fit – so we created a new way to test if they do</a>
</strong>
</em>
</p>
<hr>
<p>In contrast, surgical masks are designed to prevent splatter of fluid on the face and are loose-fitting, causing unfiltered air to leak in through the gaps around the mask. The filtration of a surgical mask is not regulated. </p>
<p>In other words, respirators are designed for respiratory protection and cloth and surgical masks are not. </p>
<p>The review starts with an assumption that masks provide respiratory protection, which is flawed. An understanding of these differences should inform both studies and reviews of those studies. </p>
<h2>The studies addressed quite different questions</h2>
<p>A common mistake in meta-analysis is to combine apples and oranges. If apples work but oranges don’t, combining all studies in a single average figure may lead to the conclusion that apples do not work. </p>
<p>This Cochrane Review combined RCTs where face masks or respirators were worn <em>part</em> of the time (for example, when caring for patients with known COVID or influenza: “occasional” or “targeted” use) with RCTs where they were worn at <em>all</em> times (“continuous use”). </p>
<p>Because both SARS-CoV-2 and influenza viruses are airborne, an unmasked person could be infected anywhere in the building and even after an infectious patient has left the room, especially since some people have <a href="https://www.pnas.org/doi/10.1073/pnas.2109229118">no symptoms</a> while contagious. </p>
<figure class="align-center ">
<img alt="Clinicians in PPE pulls up her gloves" src="https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508255/original/file-20230206-21-bn9aws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The results will depend on whether they’re occasionally or continuously used.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/hYcSP6SpoK0">Unsplash/Viki Mohamad</a></span>
</figcaption>
</figure>
<p>Most RCTs of masks and N95s included in the review have not had a <a href="https://jamanetwork.com/journals/jama/fullarticle/184819">control arm</a> – therefore finding no difference could indicate equal efficacy or equal inefficacy. </p>
<p><a href="https://jamanetwork.com/journals/jama/fullarticle/2749214">Studies</a> examining wearing a surgical mask or respirator (such as an N95) only when in contact with sick people or when doing a high-risk procedure (occasional use) have generally shown that, when worn in this way, there is no difference. </p>
<p>An RCT comparing occasional versus continuous use of respirators in health care workers <a href="https://www.atsjournals.org/doi/10.1164/rccm.201207-1164OC?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubme">showed</a> N95 respirators and surgical masks were equally <em>ineffective</em> when only worn occasionally by hospital workers. They had to wear them <em>all the time at work</em> to be protected. </p>
<p>We also combined only apples and apples in a <a href="https://onlinelibrary.wiley.com/doi/10.1111/irv.12474">meta-analysis</a> of two RCTs conducted in exactly the same way and measuring the same interventions and outcomes. We found N95 respirators provide <em>significant protection</em> against respiratory infections when surgical masks did not, even against infections assumed to be “droplet spread”. </p>
<h2>Most trials addressed only half the question</h2>
<p>Face masks and respirators work in two ways: they protect the wearer from becoming infected <em>and</em> they prevent an infected wearer from spreading their germs to other people. </p>
<p>Most RCTs in this Cochrane Review looked only at the former scenario, not the latter. In other words, the researchers had asked people to wear masks and then tested to see if those people became infected. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-viral-infections-skyrocket-masks-are-still-a-tried-and-true-way-to-help-keep-yourself-and-others-safe-195788">As viral infections skyrocket, masks are still a tried-and-true way to help keep yourself and others safe</a>
</strong>
</em>
</p>
<hr>
<p>A previous <a href="https://pubmed.ncbi.nlm.nih.gov/20092668/">systematic review</a> found face masks worn by sick people during an influenza epidemic reduced the risk of them transmitting the infection to family members or other carers. Preventing an infection in one person also prevents onward transmission to others within a closed setting, which means such RCTs should use a special method called “cluster randomisation” to account for this. </p>
<p>Data from a RCT of N95 respirator use by <a href="https://journals.sagepub.com/doi/full/10.1177/0300060516665491?rfr_dat=cr_pub++0pubmed&url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org">health workers</a> showed even their unmasked colleagues were protected. Yet some of the trials included in the review did not use cluster randomisation.</p>
<h2>The new paper combined health and community settings</h2>
<p>This is another apples-plus-oranges issue. Different settings have widely differing risks of transmission, since airborne particles build up when sick patients are exhaling the virus in <a href="https://theconversation.com/heres-where-and-how-you-are-most-likely-to-catch-covid-new-study-174473">underventilated, crowded settings</a> especially if many infected people are present (such as in a hospital). </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1484210379093954564"}"></div></p>
<p>A genuine protective effect of masks or respirators shown in a RCT in a high-risk setting will be obscured if that trial is combined in a meta-analysis with several other RCTs that were conducted in low-risk settings. </p>
<p>A large <a href="https://www.science.org/doi/10.1126/science.abi9069">RCT in the community in Bangladesh</a> found face masks reduced the risk of infection by 11% overall and 35% in people over 60 years. In contrast, in <a href="https://onlinelibrary.wiley.com/doi/10.1111/irv.12474">hospitals</a>, N95 reduce risk by 67% against bacterial infections and 54% against viral infections.</p>
<p>Viruses like influenza also vary substantially from year to year – some years there is very little influenza, and if a RCT is conducted during such a year, it will not find enough infections to show a difference. The review failed to account for such seasonal effects.</p>
<h2>But did they actually wear the mask?</h2>
<p>The authors of the Cochrane Review acknowledged compliance with masking advice was poor in most studies. In the real world, we can’t force people to follow medical advice, so RCTs should be analysed on an “intention to treat” basis. </p>
<p>For example, people who are prescribed the active drug but who choose not to take it should not be shifted to the placebo group for the analysis. But if in a study of masking, most people don’t actually wear them, you can’t conclude that <em>masks</em> don’t work when the study shows no difference between the groups. You can only conclude that the <em>mask advice</em> didn’t work in this study. </p>
<figure class="align-center ">
<img alt="Woman fits a facemask" src="https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508256/original/file-20230206-17-y18dj7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People don’t always wear masks when advised to do so.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/woman-wearing-face-mask-3873197/">Pexels/Polina Tankilevitch</a></span>
</figcaption>
</figure>
<p>There is a great deal of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246317">psychological evidence</a> on why people do or don’t choose to comply with advice to mask and how to improve uptake. The science of masking needs to separate the impact of the <em>mask itself</em> from the impact of the <em>advice to mask</em>. </p>
<p>Mask-wearing <a href="https://www.ijidonline.com/article/S1201-9712(21)00274-5/fulltext">goes up</a> substantially to over 70% if there is an actual mandate in place.</p>
<h2>It didn’t include other types of research</h2>
<p>A comprehensive review of the evidence would also include other types of study besides RCTs. For example, a <a href="https://www.sciencedirect.com/science/article/pii/S0140673620311429">large systematic review</a> of 172 various study designs, which included 25,697 patients with SARS-CoV-2, SARS, or MERS, concluded masks were effective in preventing transmission of respiratory viruses. </p>
<p>Well-designed <a href="https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm?s_cid=mm7106e1_w">real-world studies</a> during the pandemic showed any mask reduces the risk of COVID transmission by 50–80%, with the highest protection offered by N95 respirators. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/which-mask-works-best-we-filmed-people-coughing-and-sneezing-to-find-out-143173">Which mask works best? We filmed people coughing and sneezing to find out</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/20095070/">Many lab-based studies</a> have shown respirators are superior to masks at preventing airborne respiratory infections and the <a href="https://thorax.bmj.com/content/75/11/1024.long">incremental superiority</a> from a single to two layered cloth mask to a three-layered surgical mask in blocking respiratory aerosols.</p>
<h2>Yes, masks reduce the spread of COVID</h2>
<p>There is strong and consistent evidence for the effectiveness of masks and (even more so) respirators in protecting against respiratory infections. Masks are an important protection against serious infections. </p>
<p>Current COVID vaccines protect against death and hospitalisation, but do <a href="https://fortune.com/well/2023/01/06/kraken-xbb15-omicron-covid-variant-most-transmissible-yet-could-spawn-more-immune-evasive-variants-study-china-vaccine-monoclonal-antibodies-breakthrough-infection/">not prevent infection</a> well due to waning vaccine immunity and substantial immune escape from new variants. </p>
<p>A systematic review is only as good as the rigour it employs in combining similar studies of similar interventions, with similar measurement of outcomes. When very different studies of different interventions are combined, the results are not informative.</p><img src="https://counter.theconversation.com/content/198992/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>C Raina MacIntyre receives funding from mask manufacturer Detmold for testing of their masks and is on an advisory board for mask manufacturer Ascend. She receives funding from Sanofi for investigator-driven influenza research, and from NHMRC and MRFF. She has been an expert advisor for Ontario Nurses Association (ONA) In the matter of a proceeding under the Labour Relations Act, 1995 between ONA and Hamilton Health Sciences Corporation.
</span></em></p><p class="fine-print"><em><span>Abrar Ahmad Chughtai had testing of filtration of masks by 3M for his PhD. 3M products were not used in his research. He also has worked with Paftec on research in respirators (no funding was involved).</span></em></p><p class="fine-print"><em><span>Dr Fisman has served as an expert witness for the Ontario Nurses Association and the Elementary Teachers' Federation of Ontario in legal challenges related to safer working conditions in healthcare and schools. Dr. Fisman has served on advisory boards for Pfizer, Astrazeneca, Merck, Seqirus and Sanofi vaccines against SARS-CoV-2, influenza, and S. pneumoniae. He holds current funding from the Canadian Institutes for Health Research and Health Canada.</span></em></p><p class="fine-print"><em><span>Trish Greenhalgh receives funding from UK National Institute for Health and Care Research and the NIHR School for Primary Care Research. She is affiliated with University of Oxford and University of Oslo. She has served as an unpaid adviser tot he philanthropic fund BALVI and is a member of Independent SAGE. </span></em></p>An updated Cochrane Review suggests face masks don’t reduce the spread of COVID in the community. But there are several reasons why this conclusion is misleading.C Raina MacIntyre, Professor of Global Biosecurity, NHMRC Principal Research Fellow, Head, Biosecurity Program, Kirby Institute, UNSW SydneyAbrar Ahmad Chughtai, Senior lecturer, UNSW SydneyDavid Fisman, Professor in the Division of Epidemiology, University of TorontoTrish Greenhalgh, Professor of Primary Care Health Sciences, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1851672022-06-17T10:18:02Z2022-06-17T10:18:02ZWe don’t know whether most medical treatments work, and we know even less about whether they cause harm – new study<figure><img src="https://images.theconversation.com/files/469307/original/file-20220616-20-ye31mc.jpg?ixlib=rb-1.1.0&rect=0%2C16%2C5378%2C3558&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">'I have no idea if this will work.'</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/shot-female-dietician-prescribing-nutritional-supplement-1080163670">Josep Suria/Shutterstock</a></span></figcaption></figure><p>Only one in 20 medical treatments have high-quality evidence to support their benefits, according to a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0895435622001007">recent study</a>. The study also found that harms of treatments are measured much more rarely (a third as much) as benefits.</p>
<p>Patients and doctors – and anyone who pays for them – need to know that medical treatments are safe and effective, but it’s an <a href="https://onlinelibrary.wiley.com/doi/book/10.1002/9781444342673">open secret</a> in the medical field that not all treatments, including ones that are commonly used, are safe and effective. For example, antiarrhythmic drugs were widely prescribed in the belief that they would reduce heart attack deaths until a clinical trial found that they <a href="https://www.nejm.org/doi/full/10.1056/nejm199103213241201">actually increased the risk of death</a>. </p>
<p>In another example, putting infants to sleep on their stomach was recommended based on expert opinion that babies would be less likely to choke on their vomit until large studies found that stomach sleeping increased the risk of <a href="https://iris.ucl.ac.uk/iris/publication/68455/1">sudden infant death syndrome</a>.</p>
<p>So how big is this problem? </p>
<p>In the early 2000s, researchers estimated that between <a href="https://pubmed.ncbi.nlm.nih.gov/11758290/">quarter</a> and a <a href="https://pubmed.ncbi.nlm.nih.gov/17683315/">half</a> of treatments are supported by high-quality evidence. But these estimates are now out of date and used old methods (such as researcher opinion) to determine whether the evidence was high quality or not. More recently, in 2020, a more rigorous estimate was published and found that only <a href="https://pubmed.ncbi.nlm.nih.gov/32890636/">10% of medical treatments</a> were based on high-quality evidence. However, this estimate was based on a small sample of 151 studies.</p>
<p>Meanwhile, some continue to insist that <a href="https://www.jstor.org/stable/10.1086/341855">most treatments must work</a>. How else can we explain that we live ten years <a href="https://archive.senseaboutscience.org/pages/ebm-matters.html">longer than our great-grandparents</a>? Yet the extension in lifespan is explicable at least partly by <a href="https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(08)60292-5.pdf">public health measures</a> such as clean water, better nutrition and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1447499/">restrictions on smoking</a>.</p>
<figure class="align-center ">
<img alt="Two girls drinking water in a kitchen." src="https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469468/original/file-20220617-26-haglol.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Having access to clean water partly explains our increased lifespan in the last century.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-little-multiracial-sisters-sit-table-1707844096">fizkes/Shutterstock</a></span>
</figcaption>
</figure>
<h2>A more accurate picture</h2>
<p>To resolve the controversy about the proportion of treatments that are based on good evidence, an international team of researchers from the UK (University of Oxford), US, Switzerland and Greece conducted a large study of 1,567 healthcare treatments. The sample included all treatments tested in Cochrane Reviews between 2008 and 2021. <a href="https://training.cochrane.org/handbook">Cochrane Reviews are rigorous studies</a> that amalgamate all available relevant evidence about treatments. They are often referenced in national and international <a href="https://www.cochrane.org/news/use-cochrane-reviews-inform-who-guidelines">healthcare guidelines</a>. </p>
<p>The year 2008 was chosen as the cut-off because that was when Cochrane Reviews incorporated a system called <a href="https://bestpractice.bmj.com/info/toolkit/learn-ebm/what-is-grade/">grading quality of evidence and strength of recommendations (Grade)</a> to rate how trustworthy the evidence is. Unlike the earlier estimates that often relied on opinions, Grade is more widely accepted and is used by <a href="https://www.bjanaesthesia.org.uk/article/S0007-0912(19)30643-9/fulltext">over 100 organisations around the world</a>. Using Grade results in a quality rating of high, moderate, low or very low.</p>
<p>The study revealed that 95% of treatments do not have high-quality evidence to support their benefits. Worse, the harms are reported in only about 33% of Cochrane Reviews.</p>
<p>It is particularly worrying that the harms of healthcare interventions are rarely quantified. For a doctor or patient to <a href="https://pubmed.ncbi.nlm.nih.gov/23381520/">decide whether to use a treatment</a>, they need to know whether the benefits outweigh the harms. If the harms are inadequately measured, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4603687/">an “informed choice” is not possible</a>.</p>
<p>A potential limitation of the study is that Grade might be too strict. Doctors and patients may be happy to use treatments whose benefits are not supported by high-quality evidence as long as they are supported by moderate-quality evidence. Even if this is right, the study found that less than half of treatments are supported by high or moderate-quality evidence. </p>
<p>Patients with ailments for which there are no effective treatments may be willing to try treatments that are not yet even supported by low-quality evidence. The study should not be used to constrain these patients’ choices. </p>
<p>Also, the sample may not have been representative. In theory, treatments tested in recent Cochrane Reviews may be less effective or based on lower-quality evidence than older treatments. However, given the rigour of Cochrane Reviews, this seems unlikely. </p>
<p>In practice, doctors can use <a href="https://effectivehealthcare.ahrq.gov/products/off-label-use-research-priorities/research">“off-label” treatments</a> which are less likely to have been studied in Cochrane Reviews and generally have <a href="https://www.uchicagomedicine.org/forefront/news/off-label-use-oft-not-evidence-based">lower-quality evidence to support them</a>. Despite these potential limitations, the study still showed that most treatments are not supported by high-quality evidence.</p>
<p>Doctors, patients and those who pay for them may wish to focus on treatments whose benefits and safety are established by high-quality evidence. Research funding should be allocated to generating high-quality evidence for treatments that are widely used but not yet supported by high-quality evidence about their benefits and harms. </p>
<p>Finally, potential harms should be measured with the same rigour as potential benefits. The evidence-based medicine community is <a href="https://www.bmj.com/content/308/6924/283">correct to continue calling for higher-quality research</a>, and also justified in their scepticism that high-quality evidence for medical treatments is <a href="https://pubmed.ncbi.nlm.nih.gov/26934549/">common or even improving</a>.</p><img src="https://counter.theconversation.com/content/185167/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeremy Howick receives funding from the Medical Research Council (UK)</span></em></p>Around 95% of treatments do not have high-quality evidence to support their benefitsJeremy Howick, Professor and Director of the Stoneygate Centre for Excellence in Empathic Healthcare, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1179382019-06-17T18:59:37Z2019-06-17T18:59:37ZWhat programme actions are needed to promote children’s growth in poor urban areas?<figure><img src="https://images.theconversation.com/files/279679/original/file-20190616-158936-11e0hdo.jpg?ixlib=rb-1.1.0&rect=0%2C10%2C1022%2C662&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Children in a Bangladesh slum.</span> <span class="attribution"><a class="source" href="https://search.creativecommons.org/photos/e6e79d1e-ad93-4506-915c-0116d49695a8">United Nations /Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em><a href="https://www.afidep.org/staff/nyovani-madise-ph-d/">Nyovani Madise</a>, director of research and development policy at the <a href="https://www.afidep.org">African Institute for Development Policy</a> (AFIDEP) and <a href="https://idronline.org/contributor/anuja-jayaraman/">Anuja Jayaraman</a>, a development economist associated with the <a href="https://snehamumbai.org">Society for Nutrition, Education & Health Action</a> (SNEHA), contributed to this article.</em></p>
<hr>
<p>The United Nations estimates that there are at least 1 billion people living in urban slums – poor areas in cities without adequate access to <a href="https://unhabitat.org/wp-content/uploads/2017/02/GAR2017-FINAL_web.pdf">health care, clean water and sanitation</a>. More than 90% of urban slums are in low- and middle-income nations, and the residents usually live in poverty and face insecurities in food, housing and more.</p>
<p>In many of such areas, programmes and schemes by government and NGOs are provided to help families and mitigate malnutrition. But are these effective?</p>
<h2>Understanding stunting</h2>
<p>We just completed a <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011695.pub2/full#0">Cochrane Systematic Review</a> “Nutritional interventions for preventing stunting in children (0 to 5 years) living in urban slums”. These are systematic assessments of primary research, and are internationally recognised as the highest standard in evidence-based health care.</p>
<p>Our review provides a transparent and objective evaluation of the effectiveness of treatments designed to improve health. “Stunting” is the term used to describe very short height, technically a girl or boy whose height-for-age is among the shortest 2.5% of a healthy reference group of children.</p>
<p>In some of the low-income countries where we work, <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-018-5101-x">such as Bangladesh</a> and <a href="https://www.ijmedph.org/sites/default/files/IntJMedPublicHealth_2014_4_3_247_137710.pdf">India</a>, up to 60% of the urban slum children measured fall into this category. Stunting is associated with poor health, poor school performance, and the likelihood of life in poverty both now and in the future.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279682/original/file-20190616-158949-t2j50c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ethiopia, 2016. Providing higher-quality food is not the only way to help malnourished children.</span>
<span class="attribution"><a class="source" href="https://search.creativecommons.org/photos/fcdfb108-20ab-4795-8a5d-6ab820f711c9">UNICEF Ethiopia/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Our review included 15 studies, involving 9,261 children across the world less than five years old and 3,664 pregnant women.</p>
<p>The interventions by NGOs, research organisations or government-provided maternal nutrition education, nutrient supplementation of mothers, infants, and children, such as adding zinc or iron, nutrition systems strengthening, or a combination of these.</p>
<p>None of the studies modified the diet by providing additional food to families from locally available sources and allowing them to use it as they best saw fit.</p>
<p>The scientific quality of the studies on these interventions was judged to be very low to moderate overall, because studies were not designed to cope with research problems linked to urban slum communities, such as families repeatedly moving, making it difficult to keep providing supplements or monitoring children’s height. This meant that the effectiveness of the intervention could not be properly assessed at later dates.</p>
<h2>Nutritional interventions are not as effective as they should be in poor urban areas</h2>
<p>We found four main results.</p>
<ul>
<li><p>There was no evidence of an effect of giving pregnant mothers zinc supplementation on the birth weight or length of their new-borns.</p></li>
<li><p>There was no evidence of an effect or unclear evidence of nutrient supplementation increasing height of children.</p></li>
<li><p>There was inconclusive impact of interventions supporting nutrition activities within health services.</p></li>
<li><p>However, educating mothers on good nutrition when they were pregnant did help to increase birth weight.</p></li>
</ul>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279473/original/file-20190614-158921-lpvv9x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mother and child in a Dhaka slum.</span>
<span class="attribution"><span class="source">Sophie Goudet</span></span>
</figcaption>
</figure>
<p>Another systematic review of studies that did provide additional food to families came to a <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010578/full">similar conclusion</a>: “Supplementary food effects are modest at best”.</p>
<p>These results show that new approaches are needed to promote the nutritional status of children living in urban slums or any other place where families live in poverty.</p>
<p>These findings indicate that equating stunting with malnutrition is a gross simplification of reality. A complex matrix of interacting factors – physical, environmental and emotional in relation with poverty – are the cause of stunting. All need to addressed together to reduce stunting.</p>
<h2>Addressing insecurities</h2>
<p>People rich and poor are acutely aware of insecurities of any type – think about your own insecurities, perhaps your next performance review or your relationship with a significant other.</p>
<p>Insecurities increase feelings of stress, raising the level of stress hormones (such as adrenalin and cortisol) in our bodies.</p>
<p>Chronic stress in pregnant women and in their families <a href="https://www.mdpi.com/1660-4601/12/5/4816">inhibits the hormones responsible for growth of the skeleton</a> and this results in smaller new-borns and in shorter children.</p>
<p>Parents try to do everything possible to reduce stress for their children, but the constant pressure of poverty and insecurity in slum environments overwhelms them.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279681/original/file-20190616-158921-1lmf2l0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Child in slum in Kampala, Uganda, next to open sewage. Poor health conditions may lead to severe stunting in children. July 2007.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Child_in_slum_in_Kampala_(Uganda)_next_to_open_sewage_(3110617133).jpg">I. Jurga/The Sustainable Sanitation Alliance/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>When seemingly hopeless slum conditions are changed, child health then improves. Our analysis of a comprehensive, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0205688">community-based prevention and treatment programme</a> in a slum in the western coastal city of Mumbai, India, found that it cost only US$23 per child to provide one year of improved growth and health.</p>
<p>The organisation, <a href="https://snehamumbai.org">SNEHA</a>, worked in Dharavi, one of the largest urban slums in Asia with an estimated population of 700,000 to more than 1 million.</p>
<p>The programme in partnership with ICDS provided growth monitoring, counselling, referrals, support access to treatment, and a food supplement at a day-care centre to infants and children with severe or moderate malnutrition (wasting or thinness) for 12,000 children in one year. It also provided monthly door-to-door home-based counselling for caretakers of better-nourished infants to promote appropriate feeding practices, immunisations and awareness of health problems to prevent malnutrition.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/K7ltQCdmk0k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The NGO SNEHA addresses the special needs of slum women and children in Mumbai by working to improve their health.</span></figcaption>
</figure>
<p>The community health workers delivering this programme were well accepted as they were from the slum themselves and were able to provide recommendations to the local government at district, and Greater Mumbai level to improve health care delivery policies.</p>
<p>Regular growth monitoring of children, intensive home visits by trained, motivated and well supervised community health workers, and referrals to locally available primary care contributed to the success of the program. Children were less malnourished children after the programme.</p>
<h2>Hope is what people need</h2>
<p>Fine-tuning the strategies and processes as per the need of the community, beneficiaries and public health system helped in effective implementation. In a low- and/or middle-income country like India, collaboration with NGOs for robust community engagement and liaising with public health system is very useful.</p>
<p>Our systematic review shows the need to better understand urban slums and their families. Our Mumbai slum analysis shows that appropriate, acceptable, and low-cost interventions can prevent and treat growth failure.</p>
<p>Successful interventions raise awareness, prevent malnutrition, give families the ability to care for their children and provide hope for the future. Sustaining hope requires action ‘upstream’ from the urban slum – at the level of government and private businesses – to change social, economic and political processes and reduce insecurities in water, sanitation, food, housing, education and health care. Change leading to a hopeful future is the best way to healthy growth of children in poor urban slums.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=121&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=121&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=121&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=152&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=152&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=152&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>Created in 2007 to help accelerate and share scientific knowledge on key societal issues, the AXA Research Fund has been supporting nearly 600 projects around the world conducted by researchers from 54 countries. To learn more about this AXA Research Fund project please visit the <a href="https://www.axa-research.org/en/project/sophie-goudet">dedicated page</a>.</em></p><img src="https://counter.theconversation.com/content/117938/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sophie Goudet has received funds from the AXA Research Fund to carry this research. </span></em></p><p class="fine-print"><em><span>Paula Griffiths receives funding from MRC and The British Academy through finances awarded to them from GCRF/DfID and The Newton Fund. </span></em></p><p class="fine-print"><em><span>Barry Bogin ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>In many urban poor areas such as slums, programmes by governments and NGOs are established to help families and mitigate malnutrition. But are these effective?Sophie Goudet, Researcher in nutrition, Loughborough UniversityBarry Bogin, Professor of Biological Anthropology (Emeritus), Loughborough UniversityPaula Griffiths, Professor of Population Health, Loughborough UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1001112018-07-18T09:00:51Z2018-07-18T09:00:51ZOmega 3 supplements don’t protect against heart disease – new review<figure><img src="https://images.theconversation.com/files/228058/original/file-20180717-44079-1sa5ozx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/129311027?src=7ZvRd-T1dcAABQ2Afg6FSQ-1-13&size=medium_jpg">R_Szatkowski/Shutterstock.com</a></span></figcaption></figure><p>Many people take a daily omega 3 supplement in the belief that it is good for their heart. But our latest research, a <a href="http://cochranelibrary-wiley.com/doi/10.1002/14651858.CD003177.pub3/full">systematic review</a> of 79 clinical trials, found no evidence for this belief. </p>
<p>We examined the effects of omega 3 on heart disease and stroke, deaths from heart disease and stroke, and death from any cause. Our analysis showed that omega 3 supplements do not reduce the risk of any of these – but neither do they increase the risk. </p>
<p>For decades, omega 3 and fish oil supplements have been heavily promoted as being cardio-protective. Thanks to this heavy promotion, people in the US now get more EPA and DHA (omega 3 fats) from <a href="https://www.ncbi.nlm.nih.gov/pubmed/24694001">supplements</a> than they do from their diet.</p>
<p>This strong belief in the heart health benefits of omega 3 fat sprang from <a href="https://www.sciencedirect.com/science/article/pii/S0140673671916588?via%3Dihub">observational studies</a> suggesting that the Inuit don’t suffer from heart disease, and <a href="https://www.sciencedirect.com/science/article/pii/S0140673689908283?via%3Dihub">two early</a> <a href="http://circ.ahajournals.org/content/105/16/1897.long">trials</a> suggesting benefits of eating fish and of taking fish oil supplements. In the excitement, this message stuck, despite <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2808%2961239-8/abstract">follow-up studies</a> from both research groups, in slightly different participants, having more negative results. In fact, in <a href="https://www.nature.com/articles/1601539">one of the studies</a>, men with angina who were randomly assigned to take omega 3 supplements were at greater risk of “cardiac death” than those who weren’t assigned to take the supplement.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=981&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=981&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=981&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1233&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1233&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228057/original/file-20180717-44091-1gn091d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1233&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People have been plugging cod liver oil for a long time.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=36117031">Wellcome Images/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>WHO wants to know</h2>
<p>We wanted to understand the health benefits of omega 3 fats, and so did the World Health Organisation (WHO), as it is updating its guidance on fats. The WHO commissioned us to carry out this review and meta-analysis as part of a series of reviews on the effects of omega 3 supplements on health. (Subsequent reviews will investigate their impact on cognition, diabetes, cancer, depression, inflammatory bowel disease and body fat.) </p>
<p>For this systematic review, we looked at all the randomised controlled trials – the gold standard of clinical research – of omega 3 fats, with a duration of at least 12 months. We found 79 trials, that between them had 112,059 participants. The duration of the follow-up ranged from one year to eight years.</p>
<p>Within this set of trials, over 8,000 people died, 4,544 died of heart disease, 5,469 had a coronary event (heart attack or angina), 1,822 had a stroke and 3,788 experienced arrhythmia. With these large numbers, we had robust statistics – known in the trade as “statistical power” – to determine the effects of omega 3 on these outcomes. Our results showed little or no effect of being randomly assigned to take omega 3 supplements on any of these outcomes. </p>
<p>When we separated out the 25 studies that used the best methods, such as “blinding” the participants and the researchers to which group was getting the omega 3 and which the placebo, the effect of omega 3 on the outcomes was even weaker. This suggests that when we reduce the potential for bias in omega 3 trials, there is even more clearly no effect of omega 3 supplements. </p>
<p>It looks as though our belief in omega 3 supplements over all these years may have been driven by a few flawed studies and our own bias.</p><img src="https://counter.theconversation.com/content/100111/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lee Hooper receives funding from World Health Organization, The Dunhill Medical Trust, Economic and Social Research Council, NHS England, and the National Institute for Health Research. </span></em></p>The final word on omega 3 supplements and heart health.Lee Hooper, Reader in Research Synthesis, Nutrition and Hydration, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/892662017-12-18T14:58:14Z2017-12-18T14:58:14ZYes we must prescribe fewer antibiotics, but we’re ignoring the consequences<figure><img src="https://images.theconversation.com/files/199700/original/file-20171218-27538-12t0hgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pills and ills. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/drug-prescription-treatment-medication-pharmaceutical-medicament-541252936?src=95CVAFs3xpmQn3gb0gGjlg-1-62">Adul10</a></span></figcaption></figure><p>Antibiotic resistance is one of the greatest challenges facing mankind. We <a href="http://www.who.int/antimicrobial-resistance/en/">risk a future</a> of common infections and minor injuries once again proving fatal – plus longer hospital stays and higher medical costs. Some infections are already no longer treatable with current drugs. <a href="https://amr-review.org">Around</a> 700,000 people die each year around the world as a result, and some studies predict 10m by 2050 – more than die from cancer. </p>
<p>To avoid this “<a href="https://www.theguardian.com/society/2017/oct/13/antibiotic-resistance-could-spell-end-of-modern-medicine-says-chief-medic">antibiotic apocalypse</a>”, everyone acknowledges we need to limit the quantities of antibiotics people are taking. One key strategy to achieve this is <a href="https://theconversation.com/we-need-more-than-just-new-antibiotics-to-fight-superbugs-44054">antimicrobial stewardship</a> – putting systems in place in hospitals and doctors’ surgeries that restrict antibiotic prescriptions by paying more attention to the type, timing, dosage and duration of courses of treatment. </p>
<p>With the UK currently close to completing a <a href="https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/244058/20130902_UK_5_year_AMR_strategy.pdf">five-year implementation plan</a> across the health service, and various <a href="http://www.who.int/hrh/news/2017/AMR2017-2.pdf">other countries also</a> at different stages of development, stewardship is undoubtedly proving <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD003543.pub4/epdf">effective</a>. There is growing evidence that interventions by managers improve best practice and reduce the length of time that patients spend on antibiotics, <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD003543.pub4/abstract">without increasing</a> mortality rates. </p>
<p>When <a href="https://academic.oup.com/jac/article-abstract/72/12/3223/4100561?redirectedFrom=fulltext">we analysed</a> the data, however, it became clear that there are also important lessons that need to be learned. The wider effects of stewardship are not well enough understood. The majority of studies into the effectiveness of tighter antibiotic restrictions have only focused on their intended outcome – cutting the quantities of drugs being prescribed. </p>
<p>Few studies have looked at other consequences, and sometimes these are not easy to predict. Even interventions that reduce the use of antibiotics can lead to unwelcome effects elsewhere in the system. </p>
<h2>Knowns and unknowns</h2>
<p>Since many consequences from tighter antibiotic restrictions are predictable, it’s important we start monitoring them from the outset. Measures commonly involve, for example, requiring frontline medics to get prior permission from a more senior colleague to make sure they’re prescribing the right antibiotic. </p>
<p>Another example is introducing stop orders, which end a course of treatment on a particular date if the clinician hasn’t specified one from the outset. Steps like these can interrupt or delay treatments, but we know little about to what extent. </p>
<p>Some restrictions will inevitably be too unwise to justify. When patients are showing symptoms of infectious pneumonia, for instance, it is common practice to start them on antibiotics before the diagnosis has been confirmed. People who turn out not to be infected will sometimes end up taking unnecessary antibiotics. But since the risks outweigh the benefits with this kind of potentially life-threatening condition, this is difficult to avoid. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/199701/original/file-20171218-27585-pkr8g6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Here’s the plan …</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/drug-prescription-treatment-medication-pharmaceutical-medicament-541252936?src=95CVAFs3xpmQn3gb0gGjlg-1-62">Rawpixel.com</a></span>
</figcaption>
</figure>
<p>But if this kind of problem is foreseeable and needs to be exempted from any stewardship system, <a href="https://academic.oup.com/jac/article-abstract/72/12/3223/4100561?redirectedFrom=fulltext">our research</a> has also thrown up consequences that couldn’t have been anticipated. In 2009, for example, the Scottish government aimed to reduce by 30% over two years rates of the <em>Clostridium difficile</em> bug, which causes stomach pains, sickness and diarrhoea. This effort involved changing the type of antibiotic normally given to patients prior to various types of surgery to protect them from post-surgical infections. </p>
<p>One result was that more orthopaedic patients <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4214537/">ended up</a> developing acute kidney infections – ten more cases per month in one hospital. The managers setting up the stewardship system did not realise that stopping the antibiotic could lead to kidney infections in these patients. They ended up having to stay longer in hospital and needing more clinical interventions as a result. </p>
<p>Unexpected consequences can also be positive sometimes. One example is <a href="https://smw.ch/article/doi/smw.2014.13981">a study</a> of over 10,000 babies thought to be at risk of sepsis, a potentially deadly infection in the blood. The study looked at whether dispensing with the routine diagnostic blood test on these babies and relying only on other clinical examinations delayed the point at which you could start those testing positive for sepsis on a course of antibiotics. </p>
<p>If so, it would mean they would need more antibiotics for a longer duration and that the blood test was therefore a necessary means of controlling levels of prescriptions. Instead, however, the study confirmed that it made no difference, and in fact meant the infants could be given antibiotics earlier – so reducing the need for prescriptions. </p>
<h2>Pause for reflection</h2>
<p>This hopefully gives a glimpse into the complexity in this area, and the limitations in simply looking at cause and effect. <a href="https://siscc.dundee.ac.uk/work/improvement-science-methods/">As part</a> of our research, we have worked with practitioners around Scotland to understand how to monitor and predict consequences more effectively. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/199702/original/file-20171218-27538-1a2ybov.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Until next time.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/patient-meeting-doctor-735167506?src=o5PGEE9iW88_z_4OqIXZXA-1-4">Rawpixel.com</a></span>
</figcaption>
</figure>
<p>We’ve now produced a <a href="https://siscc.dundee.ac.uk/work/improvement-science-methods/">framework</a> to help managers to identify risks from the outset. It promotes the idea of an “improvement pause” to review the new system after a few months and make any necessary adjustments – hopefully making all the professionals involved more confident that the changes are benefiting patients and families. Unpleasant surprises in particular need to be carefully evaluated to see if any harm being caused is enough to stop or adapt the intervention.</p>
<p>The point is that to protect patients, all outcomes associated with changes to antibiotic prescriptions need to be monitored carefully. We’re not seeing nearly enough of this happening after systems are put in place. While interventions are vital to protect us all from antibiotic apocalypse, they still need to be balanced against the needs of patients today.</p><img src="https://counter.theconversation.com/content/89266/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Madalina Toma has received funding from the Economic and Social Research Council. </span></em></p><p class="fine-print"><em><span>Julie Anderson does not receive relevant direct funding but the SISCC receives funding from Scotland's Chief Scientist Office, Health Foundation, NHS Education for Scotland and Scottish Funding Council.</span></em></p>Antimicrobial stewardship is proving effective, but we’re not fully across what is happening.Madalina Toma, Research fellow, University of DundeeJulie Anderson, Associate Director, Scottish Improvement Science Collaborating Centre, University of DundeeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/787032017-06-25T09:57:12Z2017-06-25T09:57:12ZOpen, free access to health evidence: a new precedent for Africa<figure><img src="https://images.theconversation.com/files/172011/original/file-20170602-18817-1on5b98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Clinicians can do their jobs better when they have quick, open access to scientifically rigorous research.</span> <span class="attribution"><span class="source">Penn State/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>When the World Health Organisation develops <a href="http://www.who.int/publications/guidelines/handbook_2nd_ed.pdf?ua=1">guidelines</a> on the use of health care interventions, it turns to the <a href="http://www.cochranelibrary.com/">Cochrane Library</a>. This is a collection of databases containing high quality systemic reviews and other evidence to inform decisions about health care. </p>
<p>The problem is that access to these important databases costs money. In South Africa, universities and the South African Medical Research Council could access the Cochrane Library through institutional subscriptions with the library’s publishers.</p>
<p>But most of the country’s health care workers aren’t affiliated to universities. So the library has been inaccessible where it’s most needed – in clinical settings. Technical teams within the government and those responsible for creating policies were also left out.</p>
<p>Perhaps most importantly, consumers – patients who wanted to know more about medicines and possible treatments – could pay for a personal subscription. But most people can’t afford the subscription fee. </p>
<p>Now, thanks to funding from the South African Medical Research Council (SAMRC), that’s going to change. </p>
<p>One of the SAMRC units, <a href="http://www.mrc.ac.za/cochrane/cochrane.htm">Cochrane South Africa</a>, has procured a national licence that provides “one-click” access to the Cochrane Library for everyone in South Africa. This will provide fair, equal – and free – access to evidence-based Cochrane Reviews for all. It’s a chance for practitioners, policymakers and patients to get up-to-date, scientifically rigorous information about health care.</p>
<p>This is the first time a country in Africa has bought a national licence of this kind, though other low or middle-income countries such as India have already gone this route.</p>
<h2>A valuable asset for clinicians</h2>
<p>Being able to access up-to-date, relevant evidence is <a href="http://www.samj.org.za/index.php/samj/article/view/9754">good news</a> for any health system. Access of this kind <a href="http://www.samj.org.za/index.php/samj/article/view/9754">is key</a> to improving treatment outcomes and reducing health care harms and sometimes even costs. It also boosts the chances of improved well being in a society.</p>
<p><a href="http://www.panafrican-med-journal.com/content/article/24/180/full/">Systematic reviews</a> can guide decision makers in developing policies and clinical practice guidelines. We’ve experienced this first hand. In 2007 we published a Cochrane Review about the treatment of hypertension using medications known as <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002003.pub2/full">beta blockers</a>. </p>
<p>In the decade that followed, this review has been referenced in nearly all international hypertension guidelines. It has contributed to the phasing out of the traditional approach of recommending that doctors use beta blockers as first-line treatment for the management of hypertension.</p>
<p>Clinicians see patients suffering from a host of illnesses every day. To keep up with the literature it’s estimated that they must read 17 articles a day. A Cochrane Review helps by providing an up-to-date synthesis of all relevant research on a given topic. This reduces the risk of practitioners cherry-picking only the studies with whose results they agree. Cochrane Reviews provide the most reliable evidence on what works, what does not work, and what requires further research. Treatments based on this information are therefore more likely to improve health outcomes. </p>
<p>The national licence also provides access to <a href="http://www.cochranelibrary.com/more-resources/cochrane-clinical-answers.html">Cochrane Clinical Answers</a>. These are designed to be used at the point of care, which is especially valuable for many doctors and nurses working in South Africa’s rural and remote areas. The library works well on mobile devices, so even clinics that don’t have PCs can benefit. </p>
<p>The mobile responsiveness of the Cochrane Library would allow ready access to evidence-based information on smartphones and other mobile devices.</p>
<p>There are also huge benefits in allowing patients to access such reviews.</p>
<h2>Patients benefit enormously</h2>
<p>Increasingly, the rights of patients and consumers are being recognised. They experience a growing sense of autonomy when they are able to influence health care decisions using sound information. </p>
<p>Cochrane Reviews include plain language summaries which describe review results using accessible wording and style. Patients who are researching a newly diagnosed condition can empower themselves with knowledge about potential interventions, including outcomes and risks. They are therefore able to ask the right questions, discuss treatment with more insight and even draw their doctor’s attention to new discoveries. </p>
<p>The national licence will also help policymakers and researchers. Being able to access the Cochrane Library will ensure that any health policy or guideline is underpinned by a comprehensive search and synthesis of the available literature. It will also allow researchers to identify areas where more investigation is needed.</p>
<p>The national licence has been available since June and anyone in South Africa can access the library <a href="http://www.cochranelibrary.com/">here</a>.</p><img src="https://counter.theconversation.com/content/78703/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Shey Wiysonge receives funding from the South African Medical Research Council and the National Research Foundation of South Africa.</span></em></p><p class="fine-print"><em><span>Jimmy Volmink does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>South Africa has become the first country on the continent to purchase a national licence to the Cochrane library – giving everyone access to evidence-based information about health care.Charles Shey Wiysonge, Director, Cochrane South Africa, South African Medical Research CouncilJimmy Volmink, Professor of Epidemiology and Dean of the Faculty of Medicine and Health Sciences, Stellenbosch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/797142017-06-22T10:24:50Z2017-06-22T10:24:50ZWhat’s the best way for children to lose weight? Here’s what the research says<figure><img src="https://images.theconversation.com/files/174913/original/file-20170621-30161-egex7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/374137576?src=erUKeAO2gUSH_SGAeEhvow-1-49&size=medium_jpg">Rawpixel.com/Shutterstock</a></span></figcaption></figure><p>An increasing number of children and adolescents across the world are too heavy for their age, height and sex. Fortunately, new evidence reveals that there are proven, effective ways to tackle overweight and obesity in the young. Two reviews, published today, show that combinations of diet, exercise and behavioural change produce small but important reductions in measures of body mass in school-aged children and adolescents.</p>
<p>Obese children are at increased risk of <a href="http://www.bmj.com/content/345/bmj.e4759">diabetes</a>, <a href="http://www.bmj.com/content/345/bmj.e4759">high blood pressure</a>, <a href="http://bmcpediatr.biomedcentral.com/articles/10.1186/1471-2431-13-121">asthma</a> and <a href="https://www.hindawi.com/journals/jnme/2012/134202/">sleep problems</a>. As well as physical health problems, we know that being overweight or obese in this age group is associated with low self-esteem, which can lead to <a href="http://webarchive.nationalarchives.gov.uk/20170210161227/http://noo.org.uk/uploads/doc/vid_10266_obesity+and+mental+health_final_070311_mg.pdf">mental health problems</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/20210677">poor quality of life</a>.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/18331423">Evidence shows</a> that, if left unchecked, overweight and obesity persists into adulthood. Adult obesity can often lead to <a href="http://www.who.int/mediacentre/factsheets/fs311/en/">type 2 diabetes, heart disease, stroke, some cancers</a>, <a href="http://webarchive.nationalarchives.gov.uk/20170210161227/http://noo.org.uk/uploads/doc/vid_10266_obesity+and+mental+health_final_070311_mg.pdf">mental health problems, reduced quality of life</a> and <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2809%2960318-4/abstract">shorter life expectancy</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=521&fit=crop&dpr=1 754w, https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=521&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/174922/original/file-20170621-30158-10r83tn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=521&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If not tackled, overweight and obesity can persist into adulthood.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/521268790?src=10n_6b0bOrS2X4-m0Y9xFQ-1-86&size=medium_jpg">pixinoo/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Gold-plated evidence</h2>
<p>The new research findings come from two Cochrane Reviews looking at lifestyle interventions in children aged <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD012651/abstract">six to 11</a> and adolescents aged <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD012691/abstract">12 to 17</a> years old. <a href="http://www.cochrane.org/">Cochrane Systematic Reviews</a> use robust methods to bring together all the available evidence to tell us whether interventions are effective. Together, the two reviews include findings from over 100 studies.</p>
<p>The two Cochrane Reviews published today are the last in a series of six reviews looking at different treatments to treat obesity in young people. Others, already published, have looked at the effectiveness of <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD011740/abstract">obesity surgery</a> and <a href="http://www.cochrane.org/CD012436/ENDOC_drug-interventions-treatment-obesity-children-and-adolescents">drugs</a> in older children and adolescents, interventions that <a href="http://www.cochrane.org/CD012008/ENDOC_parent-only-interventions-childhood-overweight-or-obesity-children-aged-5-11-years">target only parents</a> and <a href="http://www.cochrane.org/CD012105/ENDOC_diet-physical-activity-and-behavioural-interventions-treatment-overweight-or-obesity-preschool">lifestyle interventions in pre-school children</a>.</p>
<h2>Interventions for younger children</h2>
<p>The review of children aged six to 11 years reports on 70 studies which include over 8,000 children. Notably, most studies were conducted in wealthy countries. The parents were involved in most interventions, given their influential role in providing healthy meals and helping their children to be more active and spend less time watching TV and playing on the computer. The combined lifestyle interventions which support children to improve their diet and be more active, were provided in a variety of settings including school, healthcare settings and in the community. Whether parents were involved or where the interventions were delivered did not seem to affect the results.</p>
<p>Overall, in the six-to-11-year age group there were small body mass reductions in the short term. Other measures we looked at included self-esteem, quality of life and changes to food intake and exercise levels, but there was not enough information reported in the studies to draw any conclusions about these.</p>
<h2>…and for adolescents</h2>
<p>The review of young people aged 12 to 17 reports on 44 studies with just under 5,000 participants. Similarly, most studies were conducted in wealthy countries. Combinations of diet, exercise and behavioural interventions reduced body mass in adolescents. And where studies were conducted over longer time periods, these changes were maintained. There were no differences in terms of where the interventions took place or whether parents were involved. Larger reductions in body mass were seen where interventions were longer.</p>
<p>In adolescents, there were more studies looking at quality of life, and this seemed to improve with the combined interventions. However, there was not enough information to draw conclusions on changes in self-esteem or food intake or exercise habits.</p>
<p>The results from these reviews are encouraging, but we know that obesity is a complex and <a href="https://www.ncbi.nlm.nih.gov/pubmed/28489290">relapsing condition</a>, so we need to do more to understand which components of treatment are more effective and for whom, and how best to maintain positive changes in the long term.</p>
<p>Recent increases in the number of young children who are overweight have been observed in low and middle income countries, yet few studies have been carried out in these countries, so we don’t know whether the interventions described in the reviews will work for young people in these countries. More studies in these countries would be extremely helpful.</p><img src="https://counter.theconversation.com/content/79714/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karen Rees has received funding from the National Institute for Health Research (NIHR) Cochrane Programme Grant Scheme, Collaboration for Leadership in Applied Health Research and Care West Midlands at University Hospitals Birmingham NHS Foundation Trust, UK and Health Services and Delivery Research Scheme. </span></em></p><p class="fine-print"><em><span><a href="mailto:lena.al-khudairy@warwick.ac.uk">lena.al-khudairy@warwick.ac.uk</a> receives funding from National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care West Midlands at University Hospitals Birmingham NHS Foundation Trust, UK, and from Public Health England. </span></em></p><p class="fine-print"><em><span>Louisa Ells has received funding from Public Health England, NPRI, WHO and various English Local Authorities. She is affiliated with Public Health England (seconded as a specialist advisor 2 days/week).</span></em></p><p class="fine-print"><em><span>Emma Mead does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Two new Cochrane reviews reveal that some interventions to tackle overweight and obesity in children do work, but only in the short term.Emma Mead, Research associate and Cochrane systematic review methodologist, University of NottinghamKaren Rees, Principal Research Fellow, University of WarwickLena Al-Khudairy, Research Fellow, University of WarwickLouisa Ells, Reader in Public Health and Obesity, Teesside UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/644782016-09-05T20:13:19Z2016-09-05T20:13:19ZVitamin D may protect against severe asthma attacks and hospitalisation<figure><img src="https://images.theconversation.com/files/136031/original/image-20160831-799-15d51zn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Vitamin D seems to play a protective role when the lungs are inflamed and infected.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>There has been some debate in recent times about the association between vitamin D levels and <a href="https://theconversation.com/my-vitamin-d-levels-are-low-should-i-take-a-supplement-21738">the risk of developing certain conditions such as diabetes, colon cancer, arthritis and infections</a>. Studies show conflicting results. But when it comes to asthma, vitamin D may indeed protect against severe bouts of the illness.</p>
<p>A <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD011511.pub2/full">Cochrane review</a> published today shows that asthmatics given vitamin D had fewer severe asthma attacks that needed treatment with anti-inflammatory tablets, known as oral corticosteroids. </p>
<p>For those taking vitamin D, the average number of attacks per person per year went down from 0.44 to 0.22. This is a clinically relevant reduction, meaning it is significant enough to justify a change in treatment.</p>
<p>The Cochrane Library contains in-depth reviews, known as meta-analyses, that independently study the best available evidence generated through previous research in the field.</p>
<p>The Cochrane review also showed vitamin D reduced the likelihood of attending hospital for an acute asthma attack from six per 100 patients to around three per 100. However, vitamin D had little or no effect on day-to-day asthma symptoms or breathing tests. </p>
<p>No serious side-effects of vitamin D occurred at the doses tested and the evidence reviewed was graded as of high quality.</p>
<h2>Previous trials</h2>
<p>The meta-analysis included a comprehensive review of published and unpublished trials up to January 2016. The studies included compared children or adults with asthma who were randomly chosen to receive either vitamin D or identical dummy tablets (placebo) for at least 12 weeks. </p>
<p>Seven trials involving 435 children and two trials involving 658 adults contributed to a pooled analysis of the results. Most of the patients included had mild or moderate asthma.</p>
<p>Vitamin D comes in two forms in the body. Vitamin D3 (cholecalciferol) is made in human skin when exposed to sunlight or can be taken in the diet from eating oily fish or foods with added vitamin D or vitamin D tablets. The second form is vitamin D2 (ergocalciferol), which can be ingested in the diet, mainly by eating mushrooms. </p>
<p>Both forms are changed in the body to a chemical called 25-hydroxy-vitamin D, which can be measured in blood samples. Levels lower than 50 units (nmol/L) are widely accepted to indicate vitamin D deficiency. This is <a href="http://www.nejm.org/doi/full/10.1056/NEJMra070553">common in many populations</a>, especially where sunlight levels are low or where people cover up.</p>
<p>Previous studies in <a href="http://www.jacionline.org/article/S0091-6749(10)00657-3/abstract">both children</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/25139052">adults</a> have found a link between low vitamin D levels and increased risk of asthma attacks. Individual studies have, however, used different definitions of asthma attacks and found differing results. </p>
<p>It was therefore important to use the available evidence in a standard way to assess the effects of vitamin D on the risk of severe asthma attacks. These were defined as those requiring treatment with oral medication of corticosteroids, used to treat the swelling in the air tubes in really bad asthma.</p>
<h2>Why vitamin D?</h2>
<p>Asthma, especially in younger people and children, is a <a href="http://www.ncbi.nlm.nih.gov/pubmed/26225992">result of the same type of inflammation</a> as happens in allergies such as hay fever, food allergy and eczema.</p>
<p>Tissues in the body, such as the lungs, produce the active vitamin D form (1,25-dihydroxyvitamin D) in higher levels <a href="http://www.nejm.org/doi/full/10.1056/NEJMra070553">when they are inflamed or infected</a>. The increased vitamin D seems to <a href="http://www.ncbi.nlm.nih.gov/pubmed/26035247">help fight the infection</a> and have anti-inflammatory properties.</p>
<p>Given that viruses in the airways – <a href="http://www.ncbi.nlm.nih.gov/pubmed/16877691">during colds, for instance</a> – trigger the majority of asthma attacks, it is likely the <a href="http://www.ncbi.nlm.nih.gov/pubmed/26035247">mechanism of action of vitamin D</a> relates either to prevention of such infections, or to decreasing the resulting inflammation – or both.</p>
<p>The main limitations of the Cochrane review are that children and people with frequent severe asthma attacks were not well represented. Only 13 of the 305 children included experienced an attack that needed corticosteroids tablets, compared with 118 of 628 adults who needed the tablets. </p>
<p>Consequently, the finding that vitamin D protected against severe asthma attacks is based mainly on results from adults and may not be applicable to children. Also, the review does not provide evidence about the best dose of vitamin D or best level in the blood.</p>
<p>We need additional trials to establish if vitamin D can reduce the risk of severe asthma attacks in children and in people whose vitamin D levels are measured at the start and end of the trial.</p><img src="https://counter.theconversation.com/content/64478/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Haydn Walters receives funding from NHMRC. </span></em></p><p class="fine-print"><em><span>Julia Walters and Sean Beggs do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Asthmatics given vitamin D had fewer severe attacks that needed treatment with oral medication.Julia Walters, Senior Research Fellow, Primary Health Care/Cochrane Airways Australia Coordinator, University of TasmaniaHaydn Walters, Professorial Fellow, University of TasmaniaSean Beggs, Associate Professor, Paediatrics and Child Health, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/403712015-04-29T01:27:32Z2015-04-29T01:27:32ZPrograms to prevent child sexual abuse increase knowledge and skills but do they reduce risks?<figure><img src="https://images.theconversation.com/files/79401/original/image-20150427-23961-18b1a3e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Children who undertook school-based sexual abuse prevention programs were more likely to know where to turn if they were harmed.</span> <span class="attribution"><span class="source">from www.shutterstock.com.au</span></span></figcaption></figure><p>Child sexual abuse can have a profound impact on children’s wellbeing and development. Such abuse is associated with numerous adverse outcomes well into adulthood, making its prevention an important social and public health priority. </p>
<p>We recently completed a <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004380.pub3/abstract">Cochrane Systematic Review</a> on how effective school programs are for preventing child sexual abuse. We found that the programs were moderately effective in arming children with knowledge and skills, and that these may help them avoid some potentially dangerous circumstances. </p>
<p>They were also more likely to know where to turn if in trouble. However, it is unknown whether these gains in knowledge and skills actually decrease the likelihood of child sexual abuse.</p>
<h2>What are school child sexual abuse programs?</h2>
<p>Child sexual abuse prevention programs in schools are not new. They are among the most widely deployed sexual abuse prevention efforts delivered to children. They were <a href="http://deepblue.lib.umich.edu/bitstream/handle/2027.42/31091/0000768.pdf?sequence=1">first introduced in the USA</a> in the 1980s and were adopted in Australia in 1985. </p>
<p>The programs deliver information about child sexual abuse and strategies purported to help them avoid it such as body safety rules (things like “my body belongs to me”), distinguishing safe and unsafe touches, how to tell a trusted adult if something inappropriate has occurred, and children are not to blame.</p>
<p>Running the program in schools means large numbers of children can be reached, at relatively low cost, and without stigmatising those who may be at greater risk.</p>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/17766537">Critics have claimed</a> these programs introduce complex concepts that children may not understand, cause children to be wary of adults and misplace the burden of responsibility for protection onto children. </p>
<p>These concerns should be taken seriously. The results from this review do not imply that children are responsible for protecting themselves from sexual abuse, nor that they can even do so even with such knowledge and skills. Adults who sexually abuse kids are clearly and solely responsible for taking advantage of vulnerable children. </p>
<h2>Do the programs make a difference?</h2>
<p>To ensure that our review was as non-biased as possible, we followed the <a href="http://handbook.cochrane.org">strict guidelines</a> for all Cochrane reviews. Key among these guidelines, rather than selecting the research papers we found interesting or that had positive outcomes, we searched for every paper we could find on this topic. We also statistically combined results using rigorous meta-analytic methods.</p>
<p>We found over 13,000 papers, of which 24 met our criteria for inclusion. The trials involved nearly 6,000 children, aged five to 13 years, who took part in school-based prevention programs in the US, Canada, China, Germany, Spain, Taiwan and Turkey. The children included in these studies were drawn from the demographically diverse general population of children attending schools in these locations.</p>
<p>Fifteen programs were evaluated in the trials. Program content was taught via films, plays, songs, puppets, books and games using a range of teaching methods such as modelling, role-play, rehearsal, repetition, feedback and discussion. The duration of programs varied from one 45-minute lesson to eight 20-minute lessons.</p>
<p>We found the programs evaluated were effective in increasing children’s knowledge about child sexual abuse. Some of the studies also described skill tests in which children who took part in the programs made choices in simulated scenarios that would have placed them in less danger. Again, it is important to note that knowledge about how to avoid danger in contrived situations may not translate into actual behaviours in real situations, nor does it mean that children are any less likely to be abused even with these skills and knowledge. </p>
<p>In the 15 programs that were included in the review, children were taught such things as how to say something to a trusted adult and how to recognise situations in which coercive tricks and bribes were being used. Knowledge gains in some studies persisted for at least six months (the longest follow-up period in any of the studies). </p>
<p>We did not find evidence that the programs evaluated caused harm by increasing children’s anxiety or fear, nor did study authors report any other adverse effects. However, only three of the 24 studies tested for such outcomes.</p>
<p>We found that children exposed to programs had a higher likelihood of disclosing their abuse during or after the program (14 per 1000 in intervention groups compared with four in 1000 in groups who hadn’t been in one of the programs). However, we couldn’t be certain of this result as not all programs collected this data. Of those that did, many did not use correct analytic techniques and disclosures were not always recorded consistently.</p>
<p>There are some limitations to these findings and how they apply to school-based prevention programs currently in use. We were unable to determine the long term benefits of programs in terms of reducing the actual incidence or prevalence of child sexual abuse, and the likelihood that program participants would disclose future child sexual abuse. </p>
<p>In addition, it’s important to note that many different school-based programs are being delivered in Australia and elsewhere, some of which were not included in this review. These other programs may use substantially different content than the programs we evaluated and our findings apply only to the types of programs included in our review.</p>
<p>We still need to know a great deal more about these programs, such as their acceptability to parents and teachers, their effectiveness with particular groups of children at greater risk, which specific program components offer the strongest effects, the long-term outcomes (including a better look at disclosure of past, current and future abuse, and possible adverse events) and their costs. </p>
<p>The lack of sufficient evidence to answer these key questions is sobering given that our review also showed that the number of gold-standard program evaluations worldwide has declined substantially each decade since the 1980s.</p><img src="https://counter.theconversation.com/content/40371/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kerryann Walsh receives funding from The Ausralian Research Council.</span></em></p><p class="fine-print"><em><span>null</span></em></p><p class="fine-print"><em><span>Aron Shlonsky and Susan Woolfenden do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A Cochrane review found school-based child sexual abuse prevention programs were moderately effective in arming children with knowledge and skills that may decrease the likelihood that they will be harmed.Kerryann Walsh, Associate professor, Queensland University of TechnologyAron Shlonsky, Professor of Evidence-Informed Practice, Faculty of Medicine, Dentistry and Health Sciences, The University of MelbourneKaren Zwi, Consultant Community Paediatrician & Head of the Department of Community Child Health, Sydney Children's Hospital, and Conjoint Associate Professor with the School of Women's & Children's Health, UNSW SydneySusan Woolfenden, Consultant Paediatrician, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.