December 22, 1999: VIGOR Study Provides Clearer Evidence of Heart Problems Among Users of the Drug Vioxx

The VIGOR study’s safety panel meets for a third time and learns that as of December 1, 1999, the number of Vioxx patients who have experienced heart problems or have died is twice as high as those taking naproxen. The panelists are shown a chart with two lines—one showing the number of deaths in the Vioxx group; the other, deaths in the naproxen group. The chart shows that since the sixth week of the study, the line representing the Vioxx group has been going up at an increasingly brisk pace, while the naproxen group’s line rises slower and is relatively linear. [National Public Radio, 6/8/2006] Some members suggest that diverging lines could be “due to cardioprotective effects of Treatment B,” i.e., that naproxen is somehow reducing the risk of heart problems. [US Food and Drug Administration, 2/1/2001, pp. 6 ] The panel’s chairman, Michael Weinblatt, and Merck statistician Deborah Shapiro write a letter to Merck’s Alise Reicin advising that the company develop a plan to study the cardiovascular results before the VIGOR study is completed. When an investigation by NPR learns about this meeting, it asks three experts to comment on the chart and the panel’s decision. All three say that the study should have been called off immediately because the chart clearly showed that the risk of heart problems among those taking Vioxx increased with time. The panel, in a statement to NPR, claims that it did not cancel the study noting that it was not clear to the panelists at the time whether the different rates of heart problems and deaths were a result of Vioxx causing the cardiovascular problems, or naproxen preventing them. But no study has ever proven that naproxen is cardioprotective. [National Public Radio, 6/8/2006; National Public Radio, 6/8/2006]