Objectives: To determine whether a combination of anti-rheumatic drugs is associated with the risk of coronary artery diseases (CAD) in incident rheumatoid arthritis (RA) patients.
Methods: This population-based cohort study used administrative data to identify 6260 newly-diagnosed patients with RA (age ≥20 years) as the study group. The study end-point was occurrence of CAD according to the ICD-9-CM codes. Exposure to different combinations of drugs and the risk of CAD was assessed. These included different combinatiosn of celecoxib (Cx), hydroxychloroquine (HCQ), methotrexate (MTX), and sulfasalazine (SSZ). Patients who never used Cx, HCQ, MTX, or SSZ were used as a reference group. A Cox proportional hazards model was used to estimate the hazard ratio (HR) of disease after controlling for demographic and other co-morbidities. When the proportionality assumption was violated, the spline curve of the Scaled Schoenfeld residuals was fitted to demonstrate the estimated effect on CAD over time for drug usage.
Results: Among RA patients, the adjusted HR (95% confidence interval) of CAD for "Cx only", "Cx and HCQ ever", and "Cx, HCQ, MTX, and SSZ ever", were 0.29 (0.19-0.44), 0.46 (0.24-0.88), and 0.42 (0.24- 0.75), respectively, during the first period of 0-3, 4, or 7 years. However, they became 1.04 (0.78-1.38), 1.16 (0.62-2.19), and 0.59 (0.32-1.08), respectively, during the second time period of 3, 4, or 7-10 years. The adjusted HR (95% CI) of CAD for "Cx, MTX, and SSZ ever" remains constant at 0.12 (0.02-0.89).
Conclusions: Celecoxib-DMARDs drug combinations were associated with reduced CAD risk on incident RA patients, and some of them exhibited the time-varying drug effect.
Keywords: Coronary artery diseases; DMARDs; celecoxib; cohort study; rheumatoid arthritis.