Treatment Persistence in Patients Cycling on Subcutaneous Tumor Necrosis Factor-Alpha Inhibitors in Inflammatory Arthritis: A Retrospective Study

Introduction: Biologic treatments including subcutaneous tumor necrosis factor-alpha inhibitors (SC-TNFis) have greatly improved disease management of rheumatoid arthritis (RA), psoriatic arthritis (PsA) and spondyloarthritis (SpA) (collectively inflammatory arthritis, IA). Nevertheless, some patients discontinue their first-line treatment; for them, one option may be a subsequent line of the same treatment class (i.e., cycling). The aim of this study was to assess treatment persistence between first- and second-line therapy in Swedish IA patients cycling on SC-TNFis. Methods: Using data from the Swedish Health Data Registers, adult IA patients filling prescriptions between May 1, 2010, and October 31, 2016, for a SC-TNFi (adalimumab, etanercept, certolizumab and golimumab) were included. Treatment persistence was derived based on information from filled prescriptions and a 60-day grace period. Unadjusted and adjusted marginal Cox proportional hazards models were fitted to estimate the relative risk of discontinuation across treatment lines, using robust sandwich covariance matrix estimates to account for intrapatient dependence (i.e., multiple treatment lines per patient). The analysis was restricted to the first two lines of treatment. Results: Of the eligible patients, 3181 were identified as cyclers. Among these, most were female (68%), and 48%, 28% and 24% were diagnosed with RA, AS and PsA, respectively. Both the unadjusted and adjusted analyses showed that the relative risk of discontinuing SC-TNFi treatment was significantly lower in second compared to first line (hazard ratio: 0.56 [0.53, 0.59] and 0.59 [0.56, 0.62], respectively). This finding was also consistent across IA indications. Conclusions: In this study of patients cycling on SC-TNFis in IA, persistence was greater in second-compared to first-line treatment. The finding was consistent across all IA indications. Hence, patients who discontinue their first-line treatment may still benefit from treatment with an alternative SC-TNFi as a second-line therapy in IA.