Drug tolerability and reasons for discontinuation of seven biologics in elderly patients with rheumatoid arthritis -The ANSWER cohort study-

BACKGROUND: The aim of this study is to evaluate the retention rates and reasons for discontinuation for seven biological disease-modifying antirheumatic drugs (bDMARDs) in a real-world setting of elderly patients (65 years of age or older) with rheumatoid arthritis (RA). METHODS: This multi-center, retrospective study assessed 1,098 treatment courses of 661 patients with bDMARDs from 2009 to 2018 (females, 80.7%; baseline age, 71.7 years; disease duration 10.5 years; rheumatoid factor positivity 81.3%; Disease Activity Score in 28 joints using erythrocyte sedimentation rate, 4.6; concomitant prednisolone dose 2.8 mg/day (45.6%) and methotrexate dose 4.4 mg/week (56.4%); and 60.2% patients were bio-naïve). Treatment courses included abatacept (ABT; n = 272), tocilizumab (TCZ; n = 234), etanercept (ETN; n = 184), golimumab (GLM; n = 159), infliximab (IFX; n = 101), adalimumab (ADA; n = 97), and certolizumab pegol (CZP; n = 51). Drug retention rates and discontinuation reasons were estimated at 36 months using the Kaplan-Meier method and adjusted for potential clinical confounders (age, sex, disease duration, concomitant PSL and MTX, starting date and switched number of bDMARDs) by Cox proportional hazards modeling. RESULTS: A total of 51.2% of treatment courses were stopped, with 25.1% stopping due to lack of effectiveness, 11.8% due to toxic adverse events, 9.7% due to non-toxic reasons, and 4.6% due to remission. Drug retention rates for each discontinuation reason were as follows; lack of effectiveness [from 55.4% (ETN) to 81.6% (ABT); with significant differences between groups (Cox P<0.001)], toxic adverse events [from 79.3% (IFX) to 95.4% (ABT), Cox P = 0.043], and remission [from 94.2% (TCZ) to 100.0% (CZP), Cox P = 0.58]. Finally, overall retention rates excluding non-toxic reasons and remission for discontinuation ranged from 50.0% (ETN) to 78.1% (ABT) (Cox P<0.001). CONCLUSIONS: ABT showed lowest discontinuation rate by lack of effectiveness and by toxic adverse events, which lead to highest overall retention rates (excluding non-toxic reasons and remission) among seven bDMARDs in adjusted model of elderly RA patients.