Antidepressant Effectiveness Probably Overstated: Report

By Amanda Gardner
HealthDay Reporter
Wednesday, January 16, 2008; 6:00 PM

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WEDNESDAY, Jan. 16 (HealthDay News) -- A systematic review of studies on antidepressants concludes that the positive effects of these drugs are probably overstated in the medical literature.

But it's not clear if the bias comes from a reluctance to submit negative manuscripts or decisions by journals not to publish them, or a combination of both, according to Oregon Health and Science University researchers, whose report is published in the Jan. 17 issue of the New England Journal of Medicine.

The researchers compared drug efficacy inferred from published studies with drug efficacy reported to a mandatory U.S. government registry of clinical trials, in which all results, including raw data, must be included.

Only 51 percent of studies in the U.S. Food and Drug Administration registry were considered by the agency to have positive results.

In the published medical literature, however, 94 percent of studies appeared positive.

The increase in the effectiveness of the drug ranged from 11 percent to 69 percent for individual drugs, and was 32 percent overall. The antidepressant Wellbutrin appeared to show a high level of bias.

The authors also noted that studies that were not positive were often published with a slant that made them seem positive.

"For the average patient, yes, these drugs are effective, just less effective than they appear," said study author Dr. Erick Turner, an assistant professor of psychiatry and pharmacology at Oregon Health Sciences University. "Don't be overly disappointed if you don't have an excellent response to the first antidepressant you try. You might have to try two or three, and you might need to add psychotherapy."

One expert hailed the finding.

"This is, in my opinion, an excellent paper and what it shows is really consistent with the past five years," said Adil Shamoo, founder of Citizens for Responsible Care and Research and a professor of biochemistry and molecular biology at the University of Maryland School of Medicine in Baltimore. "Publications have indicated that [the] industry basically has a tendency to bias publications towards positive results and to not publish negative results."