Vioxx trial data shows early cardiovascular risk

Led by Joseph Ross, MD, MHS, Assistant Professor of Geriatrics and Palliative Medicine and of Medicine at Mount Sinai School of Medicine, a team of six investigators analyzed 30 randomized, placebo-controlled trials of Vioxx that were made available through litigation and published their findings in the November 23 issue of Archives of Internal Medicine. Under new FDA disclosure requirements, the analysis may also serve as a blueprint for other independent post-market pharmaceutical safety studies.

"Independent, objective investigators can play a more active role in pharmaceutical safety surveillance, ideally in concert with the FDA and industry," said Dr. Ross. "Our study is an analytic approach that can be used to inform public health efforts. Comprehensive, rigorous analysis of clinical trial data allows the earlier identification of drug risks, promoting more informed treatment decisions, protecting the public's health, and perhaps saving lives."

The research team identified 30 randomized, placebo-controlled trials that enrolled a combined 20,152 individuals, lasted from four weeks to four years and assigned a range of 17 to 2,586 participants to take doses of Vioxx ranging from 12.5 milligrams to 50 milligrams. The authors pooled the data from these studies and analyzed the results cumulatively, as information from each newly completed clinical trial became available.

Their analysis showed that safety concerns arose almost four years before the drug was withdrawn from the market. Dr. Ross and his colleagues found that as of December 2000 -- when 21 of the 30 studies had been completed -- there was a strong concern that patients taking Vioxx were at a greater risk for adverse events or death from cardiovascular conditions or blood clots. Thereafter, collected data through June 2001 showed Vioxx to be associated with a 35 percent increase in risk of a cardiovascular event or death. The association with cardiovascular risk strengthened as more data became available. As of April 2002, the pooled analysis showed a 39 percent increased risk, and as of September 2004, a 43 percent increased risk.

Merck introduced Vioxx to the market in May 1999 and the drug quickly became a commercial success, with sales reaching $2 billion annually.

Dr. Ross and his colleagues performed their analysis in an effort to provide a blueprint for use of clinical trial data. In their paper, the authors concluded, "Because the recently enacted FDA Amendments Act requires public disclosure of trial results within the ClinicalTrials.gov database within 12-24 months of study completion, including both efficacy and safety outcomes, clinical trial data should be available to conduct iterative meta-analyses independent of the FDA and manufacturers."

"Physicians and the public deserve to be in a position to make informed choices about risk and benefits [of pharmaceutical products]," they wrote. "And the early disclosure and dissemination of information about potential risk after its recognition must be required."

Substantial amounts of clinical trial data that have rarely been fully utilized to understand drug efficacy or safety should now be available and can be used by independent investigators to complement and corroborate surveillance done by the FDA and the companies.