tag:theconversation.com,2011:/uk/topics/anti-hypertensives-12409/articlesAnti-hypertensives – The Conversation2016-07-21T06:06:35Ztag:theconversation.com,2011:article/626842016-07-21T06:06:35Z2016-07-21T06:06:35ZBlood pressure targets – what does the new guideline say and how low should you go?<p>This week, the Heart Foundation launched <a href="http://heartfoundation.org.au/images/uploads/publications/PRO-167_Hypertension-guideline-2016_WEB.pdf">new national guidelines</a> on the management of high blood pressure (hypertension). There are several changes since the last edition, but the one <a href="http://www.medicalobserver.com.au/medical-news/australia-adopts-lower-bp-target">making headlines</a> is a lower blood-pressure target. Instead of aiming for a (systolic) target of 140 in most people with hypertension, 120 is recommended for many.</p>
<p>On a careful read, <a href="https://mja.com.au/system/files/issues/10.5694mja16.00526.pdf">the changes</a> seem cautious and well-aligned with recent evidence.</p>
<p>But a danger of reducing the new BP target to a headline is it might sound like we should be getting everyone’s blood pressure down to 120. That’s definitely not what the new guidelines say, or what the evidence supports. It’s complex, and here I’ll try to explain the details.</p>
<h2>What is high blood pressure, and why worry about it?</h2>
<p>Blood pressure is the force with which blood pushes on the walls of the arteries in the body. With every beat of the heart, this pressure swerves up, and its maximum is called the systolic blood pressure. Then, as the heart relaxes between beats, the pressure falls, and its minimum is called the diastolic blood pressure. Combining these two measurements yields the familiar top/bottom blood-pressure numbers – for example, 120/80, which is a textbook “normal” reading.</p>
<p>Hypertension is defined as a resting blood pressure consistently above 140/90, over several occasions. We need several readings because blood pressure is fickle, changing for many reasons. One is the “white coat effect” of being in a room with a doctor. For this reason, <a href="https://mja.com.au/system/files/issues/10.5694mja16.00526.pdf">the new guidelines</a> also emphasise the importance of blood-pressure measurements taken automatically by a machine, and often elsewhere than in a doctor’s office.</p>
<p>Hypertension is <a href="http://www.ncbi.nlm.nih.gov/pubmed/18456100">a major risk factor</a> for cardiovascular diseases such as heart attack and stroke. Medicines to reduce blood pressure (antihypertensives) <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001841.pub2/abstract">can prevent</a> some of these nasty events.</p>
<p>How much we worry about the risks posed by hypertension depends in part on how high the blood pressure is – the higher it is, the higher the risk. People who have already had a heart attack or stroke are obviously at high risk of another. But there are many other risk factors too, including age, gender, smoking, diabetes and cholesterol levels.</p>
<p>For people who haven’t already had a heart attack or stroke, calculating “absolute cardiovascular risk” is usually a good idea. This is done by plugging average blood pressure, age and so on into a special calculator (like <a href="http://www.cvdcheck.org.au/">cvdcheck.org.au</a> or <a href="https://qrisk.org/2016/">QRisk</a>). The higher the absolute risk, the more likely antihypertensives are to be helpful.</p>
<h2>Blood-pressure treatment targets, and the new evidence</h2>
<p>Blood-pressure targets have changed a lot over time. An older colleague of mine remembers being taught years ago that an acceptable systolic pressure was <a href="http://www.bloodpressureuk.org/BloodPressureandyou/FAQs/Bloodpressurenumbers#wgf2">“100 plus your age”</a>.</p>
<p>For several decades, a target of below 140/90 has been recommended for most patients. A tighter target for people with diabetes came, then went, as <a href="http://www.ncbi.nlm.nih.gov/pubmed/9635947">one trial</a> seemed to support it, then <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa1001286">a bigger trial</a> refuted it. There have also been changing targets for other groups of people, such as those with kidney disease. I’ve sensed some weariness about these “shifting goalposts” among fellow doctors.</p>
<p>The trigger for the new 120 systolic target is <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa1511939">an important new trial called SPRINT</a>, which was published late last year. Nearly 10,000 people with hypertension were randomly assigned to either a 120 or a 140 systolic blood-pressure target. The average systolic pressures achieved were 121.4 and 136.2 respectively. </p>
<p>After just over three years, there were significant differences between the two groups, with fewer heart attacks and deaths in the group aiming for a blood pressure of 120.</p>
<p>But the devil is in the detail. First, the people in the SPRINT study were not at low risk – they were all at least 50 years old (average age 68) and had, on average, a calculated 10-year absolute cardiovascular risk of about 20%. So the results can’t be confidently applied to younger patients or lower-risk patients.</p>
<p>Second, the trial did not include anyone with diabetes, anyone with past stroke, or anyone living in a nursing home. So again, the results can’t be applied to these groups.</p>
<p>Third, the trial was stopped earlier than anticipated due to convincing early evidence of benefit. This is reasonable on ethical grounds, so as not to keep subjecting the 140 target group to their inferior treatment. But trials stopped early may <a href="http://www.ncbi.nlm.nih.gov/pubmed/20332404">overestimate</a> how well treatments work.</p>
<p>Fourth, the proportion of people who benefited was not large. Over the course of the study, about 60 people had to be treated (to the 120 target instead of 140) for every nasty heart or brain event prevented, and 90 people for every death averted.</p>
<p>Fifth, there were a few more harms in the group with the 120 target, such as fainting, blood chemistry (electrolyte) problems and kidney injury. (Having said that, these were few in number too, and many of these harms are more minor than the benefits above.)</p>
<p>Wisely, our new national guidelines acknowledge many of these caveats. They don’t advocate “120 for everyone”. They confine the 120 target to people like those in the SPRINT trial, with significantly raised cardiovascular risk and without diabetes or past stroke. And they advise watching carefully for the side effects seen in SPRINT.</p>
<h2>What to do</h2>
<p>If you have hypertension, you may be wondering what you should do. Because this is complicated, it’s wise to talk to your doctor. A conversation could include estimating your absolute risk and considering whether you are the sort of person the SPRINT trial suggests might benefit. </p>
<p>Be aware this is a very recent guideline change, and many of us doctors are still grappling with the evidence and feeling a bit uncertain about the new targets. Whether to aim for the new low target will depend not just on your level of risk but also your own preferences and values.</p>
<p>I’m particularly uncertain about whether to suggest a 120 target to my frail older patients. The SPRINT trial <a href="http://www.ncbi.nlm.nih.gov/pubmed/27195814">did show benefits in those over 75, including some “frail” people</a>. But as people in nursing homes were not included, I’m still a bit wary of low targets in this group. I would discuss my uncertainty with such people (or their decision-makers), explore their goals and reach a shared decision.</p>
<p>I’m also uncertain just how many medicines I should prescribe to try to reach 120. Antihypertensives tend to be added incrementally – if one isn’t enough, we add another. In SPRINT, the average person aiming for 120 ended up on about three antihypertensive drugs. </p>
<p>But some of my patients won’t make the 120 target even after four antihypertensive drugs. I’m not at all confident I should combine more than three or four antihypertensives, as evidence of benefit of such combinations is sparse.</p>
<p>People who try to reach 120 but can’t get there needn’t panic. In terms of risk reduction, getting to 120 is “the icing on the cake”. Any reduction in blood pressure, if achieved by well-proven antihypertensives, is likely to reduce risk somewhat, regardless of targets. </p>
<p>And there are other ways to reduce risk. These include lifestyle changes (quitting smoking, exercising, having a healthy diet, avoiding excessive salt and alcohol) and sometimes with other medicines (such as <a href="https://theconversation.com/worried-about-taking-statins-heres-what-you-need-to-know-19877">statins</a>).</p><img src="https://counter.theconversation.com/content/62684/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Montgomery works as a GP, and like most Australian GPs he frequently cares for people with hypertension. The new guidelines discussed in this article will probably make his job a little more difficult, and may also result in some of his patients having to see him a little more frequently.</span></em></p>New Australian blood-pressure guidelines support a new lower pressure target of 120, but not for everyone.Brett Montgomery, Senior Lecturer in General Practice, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/292122014-09-29T04:25:47Z2014-09-29T04:25:47ZHealth Check: what do my blood pressure numbers mean?<figure><img src="https://images.theconversation.com/files/58732/original/6my6vzzm-1410398588.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blood pressure refers to how hard the blood is pushing against the wall of arteries.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-181679693/stock-photo-blood-pressure-woman.html?src=-fvjqTJXfYKkxYGPcdLkLg-1-61">Image Point Fr/Shutterstock</a></span></figcaption></figure><p>If you’re an adult and have ever visited a doctor, you’ve probably had your blood pressure measured. General practitioners tend to obsess over blood pressure. But with good reason: <a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Hypertension_means_high_blood_pressure">hypertension</a>, or persistently high blood pressure, <a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Hypertension_means_high_blood_pressure">can lead to</a> heart disease, stroke and diabetes, the nation’s <a href="https://theconversation.com/australias-health-2014-report-card-experts-respond-28397">biggest killers</a>. </p>
<h2>What is blood pressure?</h2>
<p>Blood pressure refers to how hard the blood is pushing against the <a href="http://www.webmd.com/heart/picture-of-the-arteries">wall of arteries</a> – these can be thought of as the pipes that deliver blood from the heart (the blood “pump”) to the rest of the body. </p>
<p>This pressure is necessary for the blood to flow. Using a plumbing analogy, imagine the effect of a drop in water pressure to water flow from the garden hose. </p>
<p>Blood pressure naturally varies throughout the day depending on posture, activity and stress. It can also be elevated or lowered as a consequence of illness or disease.</p>
<p><a href="http://en.wikipedia.org/wiki/Stephen_Hales">Stephen Hales</a>, an 18th-century English clergyman and scientist, first measured the blood pressure of animals in a <a href="http://www4.ncsu.edu/%7Emsolufse/bpmeasurement.pdf">series of experiments</a> that involved inserting tubes into their arteries. In one experiment with a horse, he describes the blood rising to eight feet in height in the tube!</p>
<p>Blood pressure measurement would almost certainly be unpopular if it involved inserting long glass tubes into people. Happily, Italian physician <a href="http://en.wikipedia.org/wiki/Scipione_Riva-Rocci">Scipione Riva-Rocci</a> developed the conventional sphygmomanometer, or blood pressure meter, in <a href="http://ceaccp.oxfordjournals.org/content/7/4/122.full">1896</a>. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/58734/original/gpxyj9qm-1410398856.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The conventional blood pressure machine uses a column of liquid mercury.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Clinical_sphygmomanometer_in_the_Czech_Republic.jpg">Jiří Sedláček (Frettie)</a></span>
</figcaption>
</figure>
<p>Soon afterwards, Russian physician <a href="http://en.wikipedia.org/wiki/Nikolai_Korotkoff">Nikolai Korotkoff</a> discovered <a href="http://en.wikipedia.org/wiki/Korotkoff_sounds">the sounds</a> that can be heard with a stethoscope over the inner elbow while using a sphygmomanometer. His technique remains the standard method for measuring blood pressure today.</p>
<p>Interestingly, the conventional sphygmomanometer uses a column of [liquid mercury](http://en.wikipedia.org/wiki/Mercury_(element) to indicate the pressure. As mercury is so much denser than water or blood, even very elevated blood pressures result in it rising no more than about a foot. </p>
<p>This quirk of medical history gives us the modern measurement unit for blood pressure: <a href="http://en.wikipedia.org/wiki/Millimeter_of_mercury">millimetres of mercury</a> (mmHg). A blood pressure measurement of 140 mmHg literally means that the pressure will push up a column of liquid mercury 14 centimetres.</p>
<p>Two numbers are given when reporting blood pressures, such as 140/90 mmHg. The first number is the <a href="http://www.sumanasinc.com/webcontent/animations/content/bloodpressure.html">systolic blood pressure</a>. This is the pressure when the heart is contracting to pump its content of blood into the circulation.</p>
<p>The second number is the <a href="http://www.sumanasinc.com/webcontent/animations/content/bloodpressure.html">diastolic blood pressure</a>. This is the pressure when the heart is relaxing and is refilling with blood. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=482&fit=crop&dpr=1 600w, https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=482&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=482&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=605&fit=crop&dpr=1 754w, https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=605&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/58744/original/5tyx47pc-1410400159.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=605&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The heart refills the blood (left = the bottom number) and pumps it out (right = the top number).</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-109311599/stock-photo-diastole-systole-filling-pumping-of-human-heart.html?src=dt_last_search-2">udaix/Shutterstock</a></span>
</figcaption>
</figure>
<h2>What is normal?</h2>
<p>The <a href="http://www.heartfoundation.org.au/SiteCollectionDocuments/HypertensionGuidelines2008to2010Update.pdf">National Heart Foundation guidelines</a> define “normal” blood pressure withing the following range:</p>
<ul>
<li><p>Systolic blood pressure: 100 to 139 mmHg </p></li>
<li><p>Diastolic blood pressure: 60 to 89 mmHg.</p></li>
</ul>
<p>These thresholds are arbitrary, but a blood pressure less than 140/90 mmHg is not labelled as high. </p>
<p>We’re also moving away from categorical descriptions of hypertension, based on blood pressure reading alone, <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(14)61212-5/abstract">towards a model</a> where blood pressure is considered alongside other risk factors to determine whether drug or lifestyle interventions are needed. </p>
<p>Clinicians now calculate the patent’s <a href="http://strokefoundation.com.au/site/media/NVDPA-Managment-Guideline-Quick-Reference-Guide.pdf">absolute cardiovascular disease risk</a>: the probability they will have a heart attack or stroke in the short and medium term, which includes age and cholesterol levels. This <a href="http://www.cvdcheck.org.au/">calculator</a> can help you work out your absolute disease risk.</p>
<p>All adults should consider having their blood pressure measured at least <a href="http://www.racgp.org.au/your-practice/guidelines/redbook/prevention-of-vascular-and-metabolic-disease/blood-pressure/">once every two years</a>. If it’s elevated, and confirmed, you’ll work with your GP to create a management plan to lower your blood pressure. This is likely to <a href="http://www.heartfoundation.org.au/SiteCollectionDocuments/HypertensionGuidelines2008to2010Update.pdf">lifestyle changes</a> such as:</p>
<ul>
<li>getting regular physical activity</li>
<li>quitting smoking</li>
<li>reducing the amount of salt you eat </li>
<li>increasing the amount of potassium you consume (from foods such as parsley, dried apricots, some nuts, bamboo shoots, bananas, avocados, soybeans and bran)</li>
<li>losing weight</li>
<li>drinking less alcohol. </li>
</ul>
<p>Keep in mind that visiting the doctor can provoke anxiety, so the blood pressure can be elevated in response to the testing procedure itself. This has been called the “<a href="http://www.bloodpressureuk.org/BloodPressureandyou/Medicaltests/Whitecoateffect">white coat effect</a>”. </p>
<p>If this is suspected, your GP might try recording your blood pressure over a number of visits, or use ambulatory or home blood pressure monitoring to get an accurate reading.</p>
<p><strong><em>This article was co-authored by Dr Patrick Khoury, a GP registrar at the General Practice Unit, Fairfield Hospital.</em></strong></p><img src="https://counter.theconversation.com/content/29212/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Tam is a general practitioner and consults with patients who have hypertension. He otherwise does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.</span></em></p>If you’re an adult and have ever visited a doctor, you’ve probably had your blood pressure measured. General practitioners tend to obsess over blood pressure. But with good reason: hypertension, or persistently…Michael Tam, General Practitioner, and Conjoint Senior Lecturer, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/317282014-09-18T20:26:04Z2014-09-18T20:26:04ZMild high blood pressure: are we treating too many people?<figure><img src="https://images.theconversation.com/files/59405/original/vmvtvj94-1411023028.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's no proof blood pressure-lowering drugs prevent heart attacks in people with mild hypertension – but they could.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/easy-pics/8287163339">The Clear Communication.../Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>An <a href="http://www.bmj.com/content/349/bmj.g5432">article</a> in this week’s issue of the British Medical Journal calls into question a common practice: treatment of mild high blood pressure. </p>
<p>The authors argue that lowering the drug threshold for high blood pressure has exposed millions of low-risk people around the world to drug treatment of uncertain benefit, at huge cost to the health system: $32 billion annually in the United States alone. </p>
<p>It’s a provocative but thoughtful take on an important issue. But it doesn’t mean you should ditch your blood pressure-lowering drugs. Let’s consider the evidence and what it all means for people with mild high blood pressure. </p>
<p>But first, what is blood pressure, and how high is too high?</p>
<h2>Hypertension</h2>
<p>Consistently high blood pressure is called hypertension, and medicines used to bring blood pressure down are called anti-hypertensives. </p>
<p>There’s no doubt that hypertension is a <a href="http://www.ncbi.nlm.nih.gov/pubmed/18456100">major risk factor</a> for diseases like heart attacks and stroke. And there’s <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001841.pub2/abstract">good evidence</a> that anti-hypertensive medicines do work – they not only reduce blood pressure but (more importantly) many also reduce the occurrence of strokes, heart attacks and sometimes death.</p>
<p>Like the air pressure in a tyre, blood pressure can be measured numerically. Unlike a tyre, blood pressure swerves up and down with every beat and relaxation of the heart. The two numbers in a blood pressure reading indicate the maximum and minimum levels it veers between with every beat. </p>
<p>While a textbook “normal” blood pressure would be about 120/80, readings vary a lot between people, and even change from minute to minute in an individual. The fickle nature of blood pressure means we needs lots of readings (preferably during normal life rather than in a doctor’s office) to get a reliable average in a given person.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/59410/original/n2nyt6kh-1411023833.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">Anti-hypertensives have clear benefits for some people with high blood pressure.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/21560098@N06/12115824515">Nina Matthews Photography/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Exactly what blood pressure range is acceptably normal is surprisingly hard to answer. Thresholds for high blood pressure used to be more lenient, but for some years now several international guidelines (including <a href="http://www.heartfoundation.org.au/SiteCollectionDocuments/HypertensionGuidelines2008to2010Update.pdf">Australia’s</a>) have used above 140/90 as the defining threshold for hypertension.</p>
<h2>The controversy</h2>
<p>We’re confident that several anti-hypertensive medicines <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001841.pub2/abstract">reduce risk</a> for people with moderate or severe hypertension (above 160/100), and even for people with normal blood pressure who are at <a href="http://www.nejm.org/doi/full/10.1056/NEJM200001203420301">high risk</a> because of a past heart attack. </p>
<p>What’s controversial is whether the medicines benefit people with mild hypertension (140-159/90-99) who’ve not had a heart attack or a stroke. This category includes <a href="http://www.aihw.gov.au/high-blood-pressure/">a lot of people</a> – perhaps over a million Australians.</p>
<p>Central to the <a href="http://www.bmj.com/content/349/bmj.g5432">new article’s</a> argument is that, when all the available results of trials of anti-hypertensives in people with mild hypertension are <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD006742.pub2/abstract">brought together</a>, they don’t prove that such treatments save lives or prevent heart attacks or strokes. </p>
<p>Because most previous anti-hypertensive trials studied people with higher average blood pressures, it was hard for analysts to find data on treatment of people with only mild hypertension.</p>
<p>But absence of proof of benefit doesn’t mean we’re sure that treating mild hypertension is useless. It just means that we don’t know. </p>
<p>In fact <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD006742.pub2/abstract">the data</a> hinted, imprecisely, at possible reductions in death and strokes from treating mild hypertension. Though this impression was not “statistically significant” – it could quite plausibly have been a statistical illusion. Such chance findings happen easily when you measure an uncommon outcome in too few people.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/59408/original/gbxbvtqk-1411023637.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">The guidelines for when to prescribe anti-hypertensives are contradictory.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/63837019@N03/9510643032">World Granny/</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Such uncertainty is a breeding ground for controversy. The sceptical authors of the <a href="http://www.bmj.com/content/349/bmj.g5432">new article</a> take the view that, as treating mild hypertension is unproven and costly, and as the medicines can cause side effects, we should be much more cautious about prescribing them in mild hypertension. </p>
<p>On the other hand, advocates of treatment of mild hypertension take the view that too few people with mild hypertension have been studied, for too short a time, to rule out a benefit. Given the proven benefits of anti-hypertensives in other groups of people, they say it may be <a href="http://www.ncbi.nlm.nih.gov/pubmed/23152161">unethical</a> to study this further, and we should <a href="http://www.forbes.com/sites/peterlipson/2013/05/29/are-we-over-treating-high-blood-pressure/">continue treating</a> those with mild hypertension.</p>
<p>It’s a very similar debate to the <a href="https://theconversation.com/worried-about-taking-statins-heres-what-you-need-to-know-19877">recent furore</a> around prescribing of statins (cholesterol-lowering pills). Statins are <a href="http://www.ncbi.nlm.nih.gov/pubmed/15249352">life-savers</a> in patients at high risk, but do they save lives in people at low risk? Some say <a href="http://www.ncbi.nlm.nih.gov/pubmed/21989464">yes</a>, some say <a href="http://www.ncbi.nlm.nih.gov/pubmed/20585067">no</a>. While battles erupt in journals and <a href="http://theconversation.com/viewing-catalysts-cholesterol-programs-through-the-sceptometer-19817">other media</a>, doctors and their patients are left confused.</p>
<p>Adding to the confusion are the inconsistent guidelines which doctors are encouraged to follow. Faced with a middle-aged person with blood pressure of 155/95 and with no other risk factors, one major Australian guideline <a href="http://www.heartfoundation.org.au/SiteCollectionDocuments/HypertensionGuidelines2008to2010Update.pdf">encourages us GPs</a> to prescribe anti-hypertensives, while another <a href="http://strokefoundation.com.au/site/media/AbsoluteCVD_GL_webready.pdf">dissuades us</a> from doing so. (Both guidelines are endorsed by Australia’s <a href="http://www.heartfoundation.org.au">Heart Foundation</a>.)</p>
<h2>What we can all do</h2>
<p>First, all of us can try to have a healthy lifestyle: exercising, and avoiding smoking and excessive alcohol and salt. These measures lower blood pressure, but are also good for all of us regardless of our blood pressure.</p>
<p>Second, if you have hypertension, try to engage with your doctor in <a href="https://www.mja.com.au/journal/2014/201/1/shared-decision-making-what-do-clinicians-need-know-and-why-should-they-bother">shared decision-making</a>. Hopefully your doctor will acknowledge what we do and don’t know on this topic.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/59412/original/5zrbdvbs-1411024007.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Many of us should cut down on salt anyway.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-77804164/stock-photo-golden-french-fries-potatoes-ready-to-be-eaten.html?src=pp-same_artist-78030421-ibbM2BQ3dnk8cwTDoAlU8g-1">ilolab/Shutterstock</a></span>
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<p>With your doctor, consider how much risk you are at of heart attacks or strokes. If you’ve already had one of these events, then you are at very high risk, and anti-hypertensives will likely be recommended with confidence. </p>
<p>Otherwise, online <a href="http://www.cvdcheck.org.au/">tools</a> are <a href="http://www.qrisk.org/">available</a> to <a href="http://bestsciencemedicine.com/chd/calc2.html">estimate</a> your “absolute risk”. These tools are based not just on your blood pressure, but also other important factors like age, gender, smoking, diabetes and cholesterol. Mild hypertension alone may not put you at great risk, but it may be more significant when combined with other problems.</p>
<p>If medicines for mild high blood pressure do offer some (as yet theoretical) protection, then they are more likely to do so the higher your risk is. If, for example, a treatment prevented a quarter of some possible nasty events, but your risk of such an event was only 4% over five years, then your chance of the treatment preventing that event is only 1% over those five years. </p>
<p>Personally, I would opt for treatment of mild hypertension if my overall risk was high, but probably not if it was low. But you might make a different decision to me. And that’s OK – we all have different values and preferences.</p>
<p>Finally, there are things that can be done at a population level that can help blood pressure and risk. Some authors suggest worrying less about doctor visits and measurements, and instead just putting everyone over the age of 55 onto a “<a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC162259/">polypill</a>” containing several low-dose medicines. But this strategy is unproven, and involves an awful lot of pill-popping.</p>
<p>Less radical, and hopefully more acceptable, are policy measures to reduce the health impacts of smoking, alcohol and salt, and to encourage physical activity. Measures like reducing societal inequality, encouraging active transportation and ensuring access to healthy foods <a href="http://www.who.int/social_determinants/thecommission/finalreport/key_concepts/en/">might</a> do more good than doctors visits and pills.</p><img src="https://counter.theconversation.com/content/31728/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Montgomery divides his working life between academic and clinical general practice. In his clinical work he, like most GPs, frequently treats patients who have high blood pressure.</span></em></p>An article in this week’s issue of the British Medical Journal calls into question a common practice: treatment of mild high blood pressure. The authors argue that lowering the drug threshold for high…Brett Montgomery, Associate Professor in General Practice, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.