Drug decisions based on faulty evidence

‘Systematic bias’ found in drug company-sponsored research

Research funded by drug companies is more likely to produce results that favor the sponsor's product than research funded by other sources, claimed researchers in a recent issue of BMJ (formerly, British Medical Journal).

The researchers reviewed 30 studies that analyzed research sponsored by a pharmaceutical company and concluded that studies sponsored by drug companies were more likely to have outcomes favoring the sponsor than studies with other sponsors.

These results apply across a wide range of diseases, drugs, and drug classes, over at least two decades and regardless of the type of research being assessed, said the authors. This suggests that there is some kind of systematic bias to the outcome of published research funded by the pharmaceutical industry.

Possible explanations include the selection of an inappropriate comparator to the product being investigated and publication bias, they concluded.

Another article in the same issue of BMJ came to a similar conclusion, saying that drug treatment is likely to be founded on biased evidence because drug companies tend to publish studies with more favorable results.

In this study, researchers identified 42 studies submitted to the Swedish drug regulatory authority to secure marketing approval for five antidepressant drugs. These studies were then compared with studies actually published between 1983 and 1999. They found evidence of three sources of bias: duplicate publication, selective publication, and selective reporting.

For instance, 21 studies contributed to at least two publications each, and three studies contributed to five publications. Studies showing significant effects of a drug were published as stand alone publications more often than studies with non-significant results. The tendency to report the more favorable results only, in studies actually published, was a major cause for bias.

“For anyone who relies on published data alone to choose a specific drug, our results should be a cause for concern,” the researchers noted. “Without access to all studies (positive as well as negative, published as well as unpublished) and without access to alternative analyses (intention to treat as well as per protocol), any attempt to recommend a specific drug is likely to be based on biased evidence.”

SOURCES: “Pharmaceutical industry sponsorship and research outcome and quality: systematic review,” BMJ  2003;326:1167-1170, May 31, 2003.

“Evidence biased medicine — selective reporting from studies sponsored by pharmaceutical industry: review of studies in new drug applications,” BMJ  2003;326:1171-1173, May 31, 2003.