Dr Anthony Cox
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Medicines Safety Week: Finding Needles in Haystacks
It's Medicines Safety week. The twitter hashtag #medsafetyweek shows a lot of international activity to encourage awareness of the harms of medicines, with a special emphasis on the importance of everybody playing their part in reporting suspected side effects of medicines. Every report counts.
The MHRA's Yellow Card Scheme has been established since 1964 and has just reached the milestone of having a million reports submitted. When you make a single report, you might think it won't have great impact, but it can. The MHRA as part of today's celebrations have highlighted the case of a single patient reporting, leading to a change in medicine information. I think this sort of story telling about the reporting of side effects is so important to encourage further reporting. It's great to see the MHRA doing this.
However, it isn't the only story. You might think once an individual report of a suspected side effect has been analysed, it just disappears into the haystack of reports where we are looking for those valuable needles. However, because of the way in which we find side effects in databases such as the Yellow Card Scheme, through signals of disproportionality, every existing card also helps find side effects from new reports that are submitted.
Disproportionality analysis is primarily a tool to generate hypotheses on possible causal relations between drugs and adverse effects, to be followed up by clinical assessment of the underlying individual case reports. It is based on the contrast between observed and expected numbers of reports, for any given combination of drug and adverse event.
Unlike trying to find a needle in a haystack, where the haystack is in the way, finding an adverse effect in a database requires the haystack of previously submitted reports to find a possible link between a drug and a side effect.
Those million reports continue to serve a purpose.
Every report counts. Twice.
Photograph: Photo by Idella Maeland
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This is the webpage and blog of Anthony R Cox, which is mainly concerned with issues around drug safety, pharmacovigilance, and the use of medicines.