Pfizer Disputes Allegations About Withholding Results of Celebrex Trial
Pfizer on Tuesday denied claims that it concealed a four-year-old study showing a link between its COX-2 inhibitor Celebrex and an increased risk of cardiovascular problems, the Wall Street Journal reports (Hensley, Wall Street Journal, 2/2). On Monday, Public Citizen announced that an analysis of the Pfizer study, conducted in 1999 but never published, found patients taking 400 milligrams per day of Celebrex were 3.6 times as likely to have a cardiovascular event as those taking placebos. In Public Citizen's assessment of the study results, all cardiovascular events were grouped together, rather than leaving them in distinct categories as the study did.
Public Citizen's Health Research Group Director Sidney Wolfe said grouping the events together made the results statistically significant, while Pfizer's analysis of the results did not. Wolfe's analysis was reviewed by Bruce Psaty, co-director of the University of Washington's Cardiovascular Research Center and an expert on cardiac medication safety. The company's study was designed to determine whether Celebrex could be used to slow the progression of Alzheimer's disease and examined the long-term effects of high doses of the medicine in the elderly (California Healthline, 2/1).
Lon Schneider, an independent safety board member who urged Pfizer to publish the Celebrex study, said the Public Citizen analysis is flawed because it groups together side effects that have different causes and, in some cases, patients may have been counted multiple times. He added that by chance the group that received Celebrex in the study was generally sicker than those in the placebo group. Pfizer said that the study "was too small to make definitive conclusions about the risks of Celebrex," the Journal reports. In addition, the safety board allowed researchers to finish the study, which indicates "any problems weren't serious," according to the Journal.
A Pfizer spokesperson said that it is not unusual for results of a small, Phase II study to not be published if the trial does not meet its efficacy goal. She added that Pfizer shared the study's results with regulators worldwide and presented an abstract of the results at a scientific congress in 2000. Schneider said, "This is more of a failure-to-publish issue than a COX-2 issue. ... The overall information from this study should be combined with information from other studies to see how strong a signal there is" that Celebrex could lead to an increase risk of cardiovascular events (Wall Street Journal, 2/2).