Utilization of non-steroidal anti-inflammatory drugs in Quebec: adherence to the Canadian consensus on prescription guidelines.

BACKGROUND Adverse events associated with the use of non-steroidal anti-inflammatory drugs (NSAIDs) have led to the publication of Canadian prescription guidelines. Prescription practices following the publication of these guidelines and the introduction of COX-2 inhibitors in the Quebec formulary of reimbursed medications remain largely unexplored. OBJECTIVES To compare the prevalence of contra-indications and selected risk factors for NSAID-toxicity among COX-2 inhibitor users and non-selective NSAID users. METHODS A case-control analysis was conducted in a random sample of Quebec adult drug plan members who were treated with celecoxib (n=42,422 cases), rofecoxib (n=25,674 cases), full-dose (anti-inflammatory doses) of non-selective NSAIDs (n=9,673 cases), or low-dose NSAIDs (n=2,745 controls) in the year 2000. Data were obtained from the Quebec prescription and medical services databases (RAMQ). RESULTS Patients with a history of gastropathy were more likely to be prescribed COX-2 inhibitors than low-dose NSAIDs; the odds ratios were 1.73 (95%CI: 1.56-1.91) and 1.49 (1.33-1.66), respectively for celecoxib and rofecoxib. Corresponding results for concomitant use of anticoagulants were 1.95 (1.34-2.83) for celecoxib and 1.87 (1.26-2.77) for rofecoxib, and for use of corticosteroids they were 1.29 (1.08-1.54) and 1.23 (1.01-1.49). Conversely, patients with the following characteristics were less likely to receive COX-2 inhibitors than low-dose non-selective NSAIDs: age 75+ (OR=0.64; 0.56-0.72 for celecoxib, OR=0.48; 0.76-0.99 for rofecoxib), hypertension (OR=0.83; 0.75-0.92 for celecoxib, OR=0.87; 0.77-0.97 for rofecoxib), and concomitant use of diuretics (OR=0.72; 0.63-0.82 for celecoxib; OR=0.77; 0.66-0.89 for rofecoxib). CONCLUSION Patients with risk factors for NSAID gastropathy were more likely prescribed COX-2 inhibitors, while the presence of other contra-indications led to the prescription of low-dose non-selective NSAIDs. However, 12.7% of users of full-dose non-selective NSAIDs were age 75+ and 12.0% had a history of gastropathy, which are considered important risk factors for adverse events.