Antidepressant drugs much less effective than believed

The effectiveness of a dozen popular antidepressants has been exaggerated by selective publication of favorable results, according to a review of unpublished data submitted to the Food and Drug Administration and reported in the New York Times and Wall Street Journal.

In published trials, about 60 percent of people taking the drugs report significant relief from depression, compared with roughly 40 percent of those on placebo pills. But when the less positive, unpublished trials are included, the advantage shrinks: the drugs outperform placebos, but by a modest margin, concludes the new report, which appears Thursday in The New England Journal of Medicine.

This publishing bias creates numerous problems for both doctors and patients who:

...are getting a distorted view of how well blockbuster antidepressants like Wyeth's Effexor and Pfizer Inc.'s Zoloft really work, researchers asserted in this week's New England Journal of Medicine.

Since the overwhelming amount of published data on the drugs show they are effective, doctors unaware of the unpublished data are making inappropriate prescribing decisions that aren't in the best interest of their patients...

Imagine if you did a series of tests on the fairness of a coin toss but you only published the studies where the coin came up heads and discarded studies where it came up tails. Looking at these studies would give you an overwhelming, yet false sense of confidence in inaccurate results.

The resulting publication bias threatens to skew the medical professions understanding of how effective a drug is for a particular condition, the researchers say. This is particularly significant as the growing movement toward "evidence-based medicine" depends on analysis of published studies to make treatment decisions.

One expert summed it up as follows: "They [doctors] end up asking, 'How come these drugs seem to work so well in all these studies, and I’m not getting that response?'"