Merck Hid Evidence Of Vioxx Harm: Study

And so, the Vioxx saga continues. Nearly eight years after Merck withdrew the controversial painkiller over links to heart attacks and strokes, a new paper indicates the drugmaker hid evidence that Vioxx tripled the risk of cardiovascular death for more than three years before taking the pill off the market in 2004. During the same period, the paper in the American Heart Journal notes, Merck had regularly insisted such an increased did not exist.

The authors came to this conclusion after running an intent-to-treat analysis of three placebo-controlled studies that Merck conducted to determine whether Vioxx was useful in preventing or treating Alzheimer’s disease. Merck, however, did not publish such an analysis; instead, the drugmaker relied on so-called on-treatment analysis, which is not the preferred method for ferreting out potentially harmful side effects that may occur in a clinical trial (here is the abstract).

Simply put, an intent-to-treat analysis will examine patients who were on the study drug, as well as time spent off the drug, but still enrolled in the study. The on-treatment approach used by Merck will not capture as many side effects. If a drug causes people to get sick and drop out of a study, then counting only the results that occur on treatment can bias results to favor the drug being studied, since the placebo arm is unlikely to cause as many patients to drop out.

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