In their report in the Canadian Adverse Reaction Newsletter,1 Duc Vu and coauthors present their data in a table suggesting a comparison between the COX-2 agents without accounting for patient exposure or the fact that these drugs came onto the market at different times.
From this crude longitudinal data, the authors suggest that “caution should be exercised in prescribing these agents to patients at risk of cardiovascular disease.” This recommendation is made even though the authors state that the “data cannot be used to determine the incidence of adverse reactions because neither patient exposure nor the amount of time the drug was on the market has been taken into consideration.”
Although I recognize that Health Canada is attempting to take responsible measures for reporting adverse drug reactions, it is critical that inferences not be made when the data are provided without appropriate perspective. Reports such as these can do more harm than good by unnecessarily raising concern among physicians to the detriment of patient care. If Health Canada wants to improve adverse reaction reporting, it should look to evaluation procedures that combine information from postmarketing surveillance, epidemiologic research and clinical trials. The result will be a more comprehensive representation of data and one that appropriately reflects a therapy's safety profile and provides useful information to prescribing physicians.
Jean-Pierre Raynauld Rheumatic Diseases Unit Centre hospitalier de l'Université de Montréal Hôpital Notre-Dame Montreal, Que.
Competing interests: Dr. Raynauld received an honorarium and travel assistance to attend a meeting held by the Canadian Rheumatology Association. He has also received fees to speak about COX-2 inhibitors from Pharmacia, Pfizer, Merck and Genzyme.