FDA Study Estimates More Than 27,000 Heart Attacks Linked to Vioxx
Arthritis medication Vioxx, which maker Merck voluntarily withdrew from the market in September, might have contributed to an estimated 27,785 heart attacks and sudden cardiac deaths between 1999 and 2003, according to an FDA memo published online Tuesday, the Bloomberg/Baltimore Sun reports.
David Graham, associate director for science in FDA's office of drug safety and author of the memo, made the estimate based on 92.8 million U.S. prescriptions for Vioxx between 1999 and 2003. According to the memo, 27,785 more patients taking Vioxx may have had heart attacks, some causing death, than those taking Celebrex (Bloomberg/Baltimore Sun, 11/3).
The memo is part of a study Graham conducted with Kaiser Permanente (Bloomberg/New York Times, 11/3). For that research, Graham and colleagues examined records for 1.39 million members of Kaiser Permanente, including 26,748 who took Vioxx and 40,405 who were on Pfizer's COX-2 inhibitor Celebrex. The study found that high doses of Vioxx, or rofecoxib, tripled risks of heart attacks and sudden cardiac death. Graham planned to present the findings at an epidemiology conference Aug. 25, but his supervisors said the results were "too preliminary" and recommended that the study be submitted first to a medical journal so it could undergo peer review or be presented at the conference with an alternative FDA opinion.
When the study was presented Aug. 25, the abstract said, "[T]his and other studies cast serious doubt on the safety of rofecoxib" at doses exceeding 25 milligrams "and its use by physicians and patients." When Graham submitted a revised, final version to FDA on Sept. 30, FDA's announcement of the study's release did not mention specific data on cardiovascular risks (California Healthline, 11/1).
Prior to Merck's withdrawal of Vioxx, about 20 million U.S. residents had taken the medication. The Wall Street Journal on Monday reported that internal e-mails, marketing documents and interviews with outside scientists who questioned the safety of Vioxx indicated that Merck was aware of safety concerns related to the medication and sought to hide them to protect sales.
The internal documents are among those presented as evidence in lawsuits filed against Merck since 2001 on behalf of former Vioxx users who allegedly experienced heart attacks or strokes as a result of the medication (California Healthline, 11/1). Merck's shares declined 5.2%, or $1.48, to $26.80 on Tuesday, following a 9.7% loss Monday when the internal documents were revealed (Talley, Wall Street Journal, 11/3). Merck's shares have declined 42% this year.
Merck spokesperson Chris Loder said, "In general, there is no reliable way to measure the actual use of Vioxx in the population, and therefore no reliable way to estimate the actual events. Because heart attacks and strokes occur in the general population, one cannot say that if someone had an event while taking Vioxx, that Vioxx caused it."
Analyst Ira Loss of Washington Analysis said, "We are in a situation where there seems to be no end to negative reaction for Merck, even if the news has been previously reported" (Bloomberg/Baltimore Sun, 11/3). The FDA memo is available online. Note: You must have Adobe Acrobat Reader to view the report.