New research published in the on-line version of the Annals of Internal Medicine today, documents an increased risk of heart attack with one of the COX-2 inhibitors used in elderly adults with no previous history of heart attack; a group previously considered low-risk.
The study, sponsored by the Canadian Institutes of Health Research (CIHR) and conducted by researchers at the McGill University Health Centre (MUHC) in Montreal, examined the relationship between the use of all nonsteroidal anti-inflammatory drugs (NSAIDs) and the risk of heart attack in 113,927 Quebec senior citizens. Only one of these agents, a COX-2 inhibitor called Vioxx a new class of NSAIDs carried a greater risk of heart attack.
“Many believe that COX-2 inhibitors increase the chance of a heart attack in high risk groups, for example people who have already suffered a heart attack,” explains primary author Linda LÃ©vesque, a pharmacist and McGill University PhD candidate in the Department of Epidemiology and Biostatistics. LÃ©vesque worked with co-author Dr. James Brophy, a cardiologist and Director of the Technology Assessment Unit (TAU) at the MUHC and Associate Professor of Medicine at McGill University. “This study demonstrates the overall risk of heart attack is increased 24% for users of Vioxx who have not previously suffered a heart attack,” LÃ©vesque says.
The study also reveals that aspirin use can help offset the damaging effects of Vioxx. “Aspirin mitigates the risk to individuals,” confirms LÃ©vesque. “But only in those on a low dosage of Vioxx.”
The study also demonstrates that the increased risk of heart attack is only present while taking the drug. “Past users of Vioxx were not at increased risk,” explains LÃ©vesque. “While the risk more than doubles for those who are taking high doses of the drug even when using aspirin.”
COX-2 inhibitors are commonly used to relieve the pain and inflammation caused by arthritis in the elderly. These drugs are believed to increase the ‘stickiness’ of blood platelets–the tiny bodies that assist in blood clot formation. “It is possible that stickier platelets increase the chance of a blockage forming in a blood vessel of the heart,” explains LÃ©vesque. “This study contributes to the growing body of evidence concerning the cardiac safety of COX-2 inhibitors.”