Research on antidepressant drugs distorted by pharmaceutical industry

According to a recent study, authors of articles conducting meta-analyses of antidepressant drugs in clinical trials with links to industry were 22 times less likely to report negative statements about a drug than authors with no industry affiliation.

The findings were published in September in the Journal of Clinical Epidemiology. The researchers collected 185 meta-analyses of antidepressant trials listed in MEDLINE between 2007 and 2014. They looked at author affiliations and conflict of interest statements and found that 54 (29 percent) of the studies had authors who were employees of the drug maker, while 145 (78 percent) of the studies had some industry link (through funding, employment or other conflict of interest).

Fifty-eight (31 percent) of the meta-analyses contained negative comments about the drug. However, only 1 of the 54 (2 percent) meta-analyses authored by researchers employed by the pharmaceutical industry contained negative statements, compared to 57 out of 131 (44 percent) meta-analyses authored by researchers not employed by the drug maker. Of the meta-analyses by authors with no industry ties, 50 percent (19 of 38) had negative statements.

While journals try to attenuate source bias by requiring authors to list any conflicts of interest, authors often do not disclose them and journals rarely verify them. For example, the Clinical Epidemiology study found that 25 percent of the authors listing no conflict of interest did in fact have industry ties.

Meta-analyses or systematic reviews of clinical trials are important for assessing the safety and effectiveness of drugs because they synthesize data from multiple trials and can provide a fuller picture of the drug’s treatment effect. Since meta-analyses require fewer resources and take less time than randomized trials, it is not surprising that the drug industry has become heavily involved in this research.

The market for antidepressants is immense, standing at $9.4 billion in the US in 2013 alone. Thus, drug firms have a large financial incentive to produce studies that place their drugs in a favorable light and downplay risks.

The new study adds to the growing literature that has consistently found that industry-sponsored research leads to more-favorable drug assessments. However, the authors discovered even greater industry involvement than in previous studies. “The number and annual rate of publication of meta-analyses in our survey are larger than in previous evaluations, and the proportion of meta-analyses with industry involvement is more than doubled.”

New drugs require clinical trials to assess their relative safety and efficacy. However, under the profit system, participants in clinical trials typically come from at-risk populations, while the data derived from the trials is subordinated to the financial interests of the pharmaceutical industry—endangering the lives and well-being of the working class.