Published Antidepressant Studies Exaggerate Their EffectivenessJan 17, 2008 | Parker Waichman LLP Antidepressants like Effexor, Zoloft, Wellbutrin and Paxil, may not be as effective in treating symptoms of depression as once thought. That’s because studies done on many popular antidepressants have been skewed in a way that exaggerates their effectiveness. In many cases, only research that casts antidepressants in a favorable light is published. Meanwhile, studies with less-than-favorable results are often mothballed by the pharmaceutical companies that make antidepressants.
The overwhelming amount of published research on antidepressants show that these drugs are effective in treating depression and other psychological problems. But according to an article in the New England Journal of Medicine, these published studies don’t tell the whole story. According to a data review submitted to the Food & Drug Administration (FDA), the vast majority of unpublished antidepressant studies found the drugs to be less effective than those that made it into medical journals.
According to the New England Journal of Medicine, of 74 antidepressant studies reviewed, 38 were deemed favorable to antidepressants. Of those favorable studies, all but one where published. Of the unfavorable studies, 22 of 36 where never published. Even more outrageous, of the 14 unfavorable studies that were published, at least 11 mischaracterized the results and presented a negative study as positive.
The antidepressant studies that the New England Journal of Medicine looked at involved some of the most popular drugs on the market. For example, in five clinical trials done on the Pfizer drug Zoloft, two published studies showed Zoloft appeared to work better than the placebo. But in three other Zoloft trials, the placebo did just as well at reducing indications of depression. Pfizer never published the three unfavorable studies, and the company discusses only the positive results in Zoloft's literature for doctors.
Even when studies where published, researchers found that drug companies found ways to manipulate them to make findings appear more favorable to an antidepressant than they really where. For example, sometimes drug makers ignore or downplay a negative finding for the "primary outcome" -- the main question the study was designed to answer -- and highlight a positive secondary outcome. In nine of the negative studies that were published, the authors simply omitted any mention of the primary outcome, the researchers said.
According to The Wall Street Journal, sales of antidepressants total about $21 billion a year. Considering this, it is understandable that drug makers would want to protect these sales. But suppressing the results of unfavorable studies affects more than antidepressant sales. Doctors unaware of the unpublished data are making inappropriate antidepressant prescribing decisions that aren't in the best interest of their patients. Sales of antidepressants are so huge because doctors and patients have been given the wrong impression about their effectiveness. "There is a view that these drugs are effective all the time," Dr. Erick Turner, a lead researcher on the study, told the Wall Street Journal. "I would say they only work 40% to 50% of the time."