Methotrexate utilization in Rheumatoid arthritis. A register-based cohort-study of treatment re-starts after gabs of at least 90 days

OBJECTIVE: To examine restart of MTX treatment among patients with rheumatoid arthritis (RA) who discontinues treatment, and investigate predictors of restart. METHODS: A cohort study was conducted based on data from medical databases. MTX drug discontinuation was defined as a gap ≥ 90 days from the expiration of one MTX prescription to the redemption of a new one. Kaplan Meier estimates were used to compute the cumulative probability of restarting MTX treatment and Cox proportional hazard to estimate the hazard of return to treatment. A case-crossover analysis compared the frequency of events that could potentially have a transient effect on MTX restart. RESULTS: Among 788 patients, who started MTX, 299 patients experienced a gap ≥ 90 days. Within 1.4 years 50 % of these patients returned to treatment, and a total of 66 % restarted treatment during follow-up. Concurrent treatment with corticosteroid and disease-modifying antirheumatic drugs (DMARDs) tended to be negatively associated with MTX restart (OR: 0.7(95 % CI: 0.5-1.2) and (OR: 0.7 (95 % CI: 0.4-1.0)). Older patients were less inclined to restart treatment than middle-aged patients (Adjustet HR 0.7 (0.4-1.2)). Patients with a CRP > 300 nmol/L less often restarted MTX than patients with a CRP < 75 nmol/L (adjHR: 0.6 (95 % CI 0.3-1.2)), and men were more inclined to MTX restart than women (adjHR 1.30 (95 % CI 0.9-2.0)). CONCLUSION: It is important to support patients in remaining continuous users of MTX. A large proportion of RA patients who discontinued MTX later restarted treatment, but especially patients with high disease activity, old age or co-morbidity were less inclined to restart treatment.