This study is the first to specifically address the question of the timing of cardiovascular risk associated with COX-2 inhibitors such as Vioxx and Celebrex.
Conducted with McGill University Health Centre researcher James Brophy and McGill doctoral student Bin Zhang, the findings will be published on-line today in the Canadian Medical Association Journal.
"A quarter of patients who suffered a heart attack while taking Vioxx did so within two weeks of their first Vioxx prescription," says Prof. Lévesque, of Queen's Department of Community Health and Epidemiology. "This demonstrates that cardiovascular risks from taking Vioxx may occur much earlier than previously believed."
Removed from the market in September 2004 by its manufacturer, Merck, after being linked with increased risk of heart attacks and strokes, Vioxx has recently been at the centre of a number of U.S. lawsuits.
The team's 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 researchers discovered that this was the case for Vioxx.
The current study, funded by the Canadian Institutes for Health Research (CIHR), examines the timing of the cardiovascular risk associated with Vioxx, Prof. Lévesque explains. Over a three-year period they assessed a group of 30,274 Quebec seniors who had been prescribed Vioxx and had no history of previous heart attacks.
As well as finding that one in four people in the study who suffered a heart attack did so within the first two weeks of taking Vioxx, the researchers discovered that the additional cardiovascular risk actually decreases with longer duration of use. The risk of a heart attack returns to normal within one month of stopping the drug.