Drug switching patterns among patients with rheumatoid arthritis and osteoarthritis using COX-2 specific inhibitors and non-specific NSAIDs

Purpose To compare RA and OA patients' time‐to‐switch after newly initiating treatment with three most commonly used non‐specific (NS)‐NSAIDs and two COX‐2 inhibitors, celecoxib and rofecoxib. Methods Managed care enrollees newly prescribed celecoxib, rofecoxib, ibuprofen, naproxen or diclofenac were identified. Time to switch to a different NS‐NSAID or COX‐2 specific inhibitor was determined using time‐to‐event analysis and Cox proportional hazards models were used to estimate the odds ratio (OR) after controlling for potential confounders. Results The time to 25% of the cohort switching was longer for rofecoxib and celecoxib (159 and 205 days respectively) compared to the three NS‐NSAIDs (49–78 days). Patients were at the highest risk of switching within the first 100 days of therapy. After adjusting for potential confounding factors, the OR for switching to another NS‐NSAID or COX‐2 specific inhibitor ranged from 1.74 to 2.35 for the three NS‐NSAIDs compared to celecoxib (all comparisons, p