Selective cyclooxygenase-2 inhibition and cardiovascular effects: an observational study of a Medicaid population

The differential effects of selective cyclooxygenase-2 (COX-2) inhibitors compared with nonspecific nonsteroidal anti-inflammatory agents (NSAIDs) on platelet aggregation and prostacyclin/thromboxane balance have led to concerns that COX-2 inhibitors may increase the risk for cardiovascular thrombotic events. Empirical studies have generally been limited to analyses of secondary end points with low event rates in clinical trials and single event rates in observational studies, all of which have come to conflicting conclusions. This observational cohort study examines the cardiovascular risk of COX-2 inhibitors compared with nonspecific NSAIDs in Maryland Medicaid enrollees, a high-risk population.

Medical and prescription claims were analyzed for noninstitutionalized Medicaid enrollees who received at least a 60-day supply of a COX-2 inhibitor or other prescription NSAID between June 2000 and June 2002 and who did not use these drugs for at least 6 months prior. Naproxen users were excluded. We developed a logistic model of propensity for treatment with COX-2 inhibitors and stratified patients by quintiles of their propensity score. The model adjusted for demographics, indications for COX-2 inhibitors, and cardiovascular risk factors.

The study population comprised 1005 patients using COX-2 inhibitors and 5245 patients using a nonnaproxen NSAID. Of the 6250 patients, 70% were female, 50% were African American, and 30% were older than 50 years. Overall, 12% of the patients had at least 1 cardiovascular thrombotic event after treatment within the follow-up period. The propensity-adjusted odds ratio showed no significant effect of COX-2 inhibitor use on this percentage of patients (odds ratio, 1.09; 95% confidence interval, 0.90-1.33).

We did not find that COX-2 inhibitors increased cardiovascular risk over nonnaproxen NSAIDs in a high-risk Medicaid population.