...And even if we focus on the science and the studies, evidence-based medicine is still fraught with difficulty. And just one factor here is what is known as ‘publication bias’ ” which describes the phenomenon when ‘positive’ studies tend to be more readily published than ‘negative’ ones. Such shenanigans are well known in medical research, and can give a very skewed impression of drug effectiveness and its risk-benefit profile.
This week’s New England Journal of Medicine carried an interesting article which sought to identify publication bias in the area of antidepressant medication [2]. The researchers assessed a total of 74 studies that had been registered with the FDA (Food and Drug Administration) in the USA. Some of these studies had been published, but many (details below). The researchers obtained the unpublished studies via various means including the invoking of the freedom of information act.
Analysing the 74 studies, the researchers found that:
38 had positive results, and all but one of these had been published.
36 had negative results, and 22 of these had not been published at all.
Of the 36 negative studies, 11 had been published, but in a way that conveyed a positive outcome (this is not ‘publication bias’ by the way, just plain ‘bias’).
This meant that of all the published studies, 94 per cent appeared to have positive findings.
However, FDA analysis revealed that 51 per cent of studies were genuinely positive.
Overall, publication bias meant that the drugs appeared about a third more effective than they are in reality (if all trials are taken into consideration).
The lead author of this study, Dr Erick Turner, is reported as saying: The bottom line for people considering an antidepressant, I think, is that they should be more circumspect about taking it.� That sounds like good advice to me. But I’d add that this data also suggests that doctors might be a bit more circumspect about prescribing them in the first place.
This is not the first time that there’s been evidence of publication bias in the area of antidepressants. Previous analysis found the same situation seems to have gone on regarding the use of antidepressants in adolescents [3]. This Lancet review found that while published studies support the use of a variety of various antidepressants in childhood depression, unpublished data shows that, in the main, risks of treatment such as an enhanced tendency towards suicidal behaviour seem to have been significantly underplayed. All this stuff on selective publication of data on antidepressant medication makes pretty depressing reading, I reckon.