Strict guidelines that were introduced 18 months ago following the death of a young woman have transformed the way paracetamol overdoses are managed, including the introduction of the lowest threshold for antidote treatment anywhere in the world.
But at what cost? We carried out the first analysis of the impact of these changes and our study, published in the British Journal of Clinical Pharmacology, suggests that for every life saved, another 31,000 patients will be unnecessarily treated – and put at risk of serious side effects – at a cost of £17.4m.
Paracetamol is the most common over-the-counter painkiller bought in the UK and around 30m prescriptions are issued every year. It is relatively easy to combine drugs for different ailments – for example cold cures and headache tablets – and overdose accidentally, and while the vast majority of overdoses are associated with self-harm, a proportion of severe paracetamol poisonings result from people taking too much from different marketed products.
Overdose from paracetamol, accidental or otherwise, brings around 90,000 people a year into accident and emergency units in the UK each year and about a half of these will be admitted to hospital. This accounts for about a third of all hospital admissions due to drug overdoses.
Early intervention is vital to avoid death and permanent liver damage – about 95% of deaths from overdose happen because patients present too late to be treated. Many people wrongly believe that paracetamol causes you to feel sleepy, and so often think that they haven’t overdosed because they feel awake.
But overall, the survival rate from overdose over the past 40 years has been high because of a drug called acetylcysteine, which is given through a drip over 21 hours. As the antidote’s effectiveness is reduced the longer you wait after overdose, time is critical. Sadly sometimes treatment doesn’t come soon enough and patients die.
Any death, particularly of a young person, is a tragedy, and some have suggested that every paracetamol overdose patient should be treated with the antidote. But while acetylcysteine is very effective, it can have serious side effects, particularly vomiting and severe allergic reactions. These side effects are far more common in patients with lower blood paracetamol, and therefore at lowest risk of death or liver damage.
Doctors used to assess whether to treat patients with the antidote based on risk factors such as history of alcohol use, diet, how much paracetamol was in the patient’s blood and the time that had elapsed since the drug was ingested.
Acting on advice, the MHRA, the UK medicines regulator, changed their guidance in 2012. Risk assessments were abandoned and all patients with a concentration of paracetamol in their blood above a certain threshold, or those who have ingested more than a specific amount, receive treatment. Both of these thresholds were lowered to below anywhere else in the world. The MHRA estimated the changes would save a life about every two years.
Yet unlike new drugs, these treatment policy changes didn’t undergo scrutiny by the National Institute for Health and Care Excellence, the NHS watchdog. And interestingly, the MHRA doesn’t have to consider the cost implications of their decisions. Our analysis, based on data from three large acute hospitals before and after changes were implemented, suggests that £17.4m will be spent every two years to save a life.
Clearly these guidelines will be placing a tremendous burden on already strained A&E resources. And in a financially stretched health service it seems pretty clear that the MHRA overreacted on this occasion.
Tackling the challenge of late presentation and changing the way products that contain paracetamol are labelled could potentially save many lives.
In addition, new research suggests there are now better markers than paracetamol blood level alone to predict who needs antidote therapy. These now need wider testing. And based on what our study found, there now clearly needs to be a review of how paracetamol poisoning is managed and a more effective way found to save lives with less health risks and cost.