The kicker is that the patent has expired for Zoloft, which is why the data are now flowing more freely. I’ll make the case here that data were buried until they would no longer hurt sales to any meaningful extent, at which point data were published, at least partially as a public relations move to show just how “honest” the companies are with sharing both positive and negative results with the psychiatric community.
The Research: The latest study, which appears in the May 2007 Journal of Clinical Psychiatry, showed no benefit for drug over a 12-week period. Placebo tended to outperform Zoloft on the majority of outcome measures, though the differences were of a small and statistically insignificant degree. Patients were significantly more likely to drop out of treatment on Zoloft. It was unclear if there were any serious adverse events (e.g., suicide attempts, notable aggression, etc.) because the article did not mention them at all. Patients started this study between May 1994 and September 1996. The original draft of the study was received by the journal in March 2006. Nearly 10 years passed between study completion and writing up the data for publication.
Two prior studies found positive results found positive results for Zoloft and were published quickly, while these negative results languished until the Zoloft patent had expired. One earlier positive study did not list the dates during which the study occurred, but it seems clear that it was rushed to publication much quicker than the negative study. Another positive study was conducted between May 1996 and June 1997 and was published in 2000. It’s quite obvious why the positive studies were rushed to press and the negative study languished, is it not?
Do keep in mind that the magnitude of positive effect for Zoloft over placebo, even in the positive studies, was small to moderate. When even the positive news for antidepressants in treating PTSD show only modest improvement relative to placebo, one should tread cautiously.
Change of Heart: Drug companies have been criticized widely for failing to disclose clinical trial data (1, 2). In an effort to shore up the support of the medical community and the public at large, what could possibly make more sense than publishing negative trial results? Gee, look at how honest we are – we share the good news and the bad news! Of course, when the positive results are published as quickly as possible and the negative results are published after a 10 year delay, well after the negative results can pose any threat to corporate profits, I’m not impressed by their newfound dedication to transparency.Note:
If you are a journalist, this is the kind of story that would merit a broad audience. The plot is pretty simple to follow and it reeks of corporate malfeasance, a subject that is not new to Pfizer and its former cash cow antidepressant.