The researchers looked at reviews from the FDA for trials between 1987 and 2004 on 12 widely used antidepressants involving 12,564 patients, and whether the research was published. Those studies that were published were then compared against FDA versions. The found that the results determined whether and how studies were published. Most of the studies that were not positive were not published or they were published with a positive spin, such as emphasizing positive secondary outcomes when a primary outcome proved negative. While drugmakers don't have to publish all their studies, the researchers identified unpublished studies by comparing databases of medical journals with documents filed with the FDA.
In discussing their findings, the researchers wrote that the FDA deemed 38 of 74 studies to be positive and all but one of those studies was published, the researchers said. The remaining 36 were either had negative or questionable results; of those, 22 weren't published. Of the 14 that were published, 11 were mischaracterized as positive, according to the researchers, who were led by Erick Turner, a former FDA reviewer who is now an assistant professor of psychiatry, physiology and pharmacology at Oregon Health & Science University and Medical Director of the Portland Veterans Affairs Medical Centerâ€™s Mood Disorders Program.
"We found a bias toward the publication of positive results. Not only were positive results more likely to be published, but studies that were not positive, in our opinion, were often published in a way that conveyed a positive outcome. we found that the efficacy of this drug class is less than would be gleaned from an examination of the published literature alone," they concluded.
"We cannot determine whether the bias observed resulted from a failure to submit manuscripts on the part of authors and sponsors, from decisions by journal editors and reviewers not to publish, or both. Selective reporting of clinical trial results may have adverse consequences for researchers, study participants, health care professionals, and patients."