Pharmaceutical companies paint an overly rosy picture of the effectiveness of antidepressants. This emerges from a recent article in the journal PLOS Medicine, based on research by epidemiologist Ymkje Anna de Vries from the University of Groningen.
Although the situation is better than it was a few years ago, mostly positive research results are still being published. Studies that prove that the drugs are not effective or not effective enough often disappear at the bottom of the desk drawer.
More than a million Dutch people use antidepressants. Before these drugs come onto the market, their effectiveness is extensively researched in so-called clinical studies. Researchers came to the conclusion as early as 2008 that there is a publication bias: research that showed a positive effect was mainly published, while research that found no effect was published much less frequently. And when these latest studies were published, the results were usually skewed so the drugs seemed to be working.
Fourteen years later, the epidemiologist Ymkje Anna de Vries and her colleagues investigated whether this publication bias has diminished. The de Vries study shows that the situation is better than in 2008. In the past fourteen years, four new antidepressants have entered the American market. De Vries reviewed thirty registered clinical trials for these antidepressants. A positive effect was found in fifteen of these studies, meaning that the drug being studied worked significantly better than a placebo.
Although all studies that found a positive effect were published, only seven of the fifteen studies without a positive effect were also published correctly and transparently. Six studies were not published at all and two studies were published but incorrectly reported a beneficial effect. De Vries’ research shows that the situation has improved compared to 2008.
keep an eye out
De Vries: “But there is still a problem. Because of this bias, antidepressants may not work as well as you might think.” According to the researcher, it’s important that drug companies are closely monitored: “These companies have a profit motive, so there should be some kind of watchdog behind them, to make sure they report their research as cleanly as possible.”