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Short-term Vioxx use study in Canadian Medical Association Journal

The Canadian Medical Association Journal released the first study suggesting that short-term use of Vioxx elevates risk of heart attack. The adjusted relative risk rate of 1.67, however, means that 60% of heart attacks by short-term Vioxx users would have occurred anyway. To the extent courts enforce the idea that a proposed cause must be more likely than not a cause, this study should not help plaintiffs, but it's unclear to what extent courts will accept that combination of legal and scientific standards, though some have. Merck's strategy of focusing on an eighteen-month cutoff for causation, rather than on demonstrating that it acted appropriately in the face of uncertain information, could be hurt to the extent courts are willing to allow speculation beyond the 2.0 rule.

The press coverage has an interesting focus on the negative impact for Merck, while ignoring other findings of the study. The same study did not find a statistically significant increased risk rate of heart attack for users with more than one Vioxx prescription or more than three weeks of use. (And the sample-size for prevalent use was much larger than the sample-size for first-time use headlined in the news coverage.) The relative risk for all Vioxx usage was merely 1.24, suggesting that over 80% of heart attacks by Vioxx users would have happened anyway. No one seems to have asked Andy Birchfield about those results. Merck's only comment on the study to date is to note that observational studies like that in the CMAJ are inferior to clinical trials. (Elena Cherney and Heather Won Tesoriero, "Study Raises Questions On Short-Term Vioxx Use", Wall Street Journal, May 3) (via Lattman).



Rafael Mangual
Project Manager,
Legal Policy

Manhattan Institute


Published by the Manhattan Institute

The Manhattan Insitute's Center for Legal Policy.