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MUHC study reveals Vioxx related heart attacks can occur within the first two weeks of use

May 03, 2006

A quarter of patients who suffered a heart attack while taking Vioxx did so within the first two weeks of taking the drug, a new study published by MUHC investigators reveals. The research, scheduled for early online publication in the Canadian Medical Association Journal (CMAJ) today, demonstrates that cardiovascular risks from taking Vioxx may occur much earlier than previously believed. "Our previous study on COX-2 inhibitors, which included Vioxx and Celebrex, evaluated whether there was an increased risk of heart attack while taking these medications; the answer was yes for Vioxx," says Linda Levesque, a doctoral student in the Department of Epidemiology and Biostatistics at McGill University, researcher at the MUHC in Montreal and lead author of the new study. "Our current study assessed the pattern of cardiovascular risk in Québec seniors over a three year period, in order to establish the timing of this risk."

Levesque, in collaboration with Dr. James Brophy , a cardiologist/epidemiologist and Director of the Technology Assessment Unit (TAU) at the MUHC and Associate Professor of Medicine at McGill University, and Bin Zhang, also a doctoral student in the Department of Epidemiology and Biostatistics, discovered that the risk of heart attack from Vioxx is much more acute than previously recognized. "A quarter of individuals in our study who suffered an acute myocardial infarction did so within two weeks of their first Vioxx prescription," says Levesque.

"The additional cardiovascular risk from Vioxx actually decreased with longer duration of use, suggesting that the period of highest susceptibility for most people taking Vioxx may occur earlier than previously believed," noted Levesque. The study also documents that cardiovascular risk returns to normal within one month of stopping the drug.

Vioxx was voluntarily withdrawn from the market on September 30, 2004 after a study showed it doubled patients' risk of heart attacks and strokes after 18 months of use. This MUHC study is the first to specifically address the question of the timing of cardiovascular risk associated with COX-2 inhibitors.

"This study adds important new information on how the COX-2 inhibitors like Vioxx affect the heart," said Dr. Peter Liu, Scientific Director of the CIHR Institute of Circulatory and Respiratory Health. "Physicians must carefully assess the risk versus benefit, and help the patient to watch for any new symptoms during the start of these medications. We are delighted that this research from the McGill University Health Centre can help us further to better the health of Canadians."

McGill University