WASHINGTON - Antidepressant medications appear to help only very severely depressed people and work no better than placebos in many patients, British researchers said.
Researchers led by Irving Kirsch of the University of Hull reviewed a series of studies, both published and unpublished, on four antidepressants, examining the question of whether a person's response to these drugs hinged on how depressed they were before getting treatment.
They were Eli Lilly and Co.'s Prozac, also known as fluoxetine, Wyeth's Effexor, also called venlafaxine; GlaxoSmithKline's Paxil, also called Seroxat or paroxetine, and Bristol-Myers Squibb Co's drug Serzone, also called nefazodone, which it no longer markets in the United States.
In short, there was virtually no difference in the response to drug vs. placebo of patients who suffered moderate levels of depression, and a small difference for patients with very severe depression, they report in the study published this evening in the journal PLoS Medicine. That small difference was, however, clinically insignificant—that is, the difference was so small that government health authorities do not recognize it as a meaningful improvement: on a standard scale of depression, patients should improve by 3 points, but the spread between placebo and drug was only 1.8. The difference between drug and placebo was clinically meaningful only for patients at the upper end of the very severely depressed category.