Comparative Effectiveness of First‐Line Baricitinib in Patients With Rheumatoid Arthritis in the Australian OPAL Data Set

OBJECTIVE: To analyze comparative treatment persistence for first‐line baricitinib (BARI) versus first‐line tumor necrosis factor inhibitor (TNFi) in patients with rheumatoid arthritis (RA) and for first‐line BARI initiated as monotherapy versus first‐line BARI initiated with at least one conventional synthetic disease‐modifying antirheumatic drug (csDMARD). METHODS: Patients with RA who initiated BARI or TNFi as first‐line biologic or targeted synthetic DMARD from October 1, 2015, to September 30, 2021, were identified in the OPAL data set. Drug survival times to 6, 12, and 24 months were analyzed using restricted mean survival time (RMST). Multiple imputation and inverse probability of treatment weighting were used to address missing data and nonrandom treatment assignment. RESULTS: A total of 545 patients initiated first‐line BARI, including 118 as monotherapy and 427 as csDMARD combination therapy. Three thousand five hundred patients initiated first‐line TNFi. There was no difference in drug survival to 6 or 12 months for BARI compared with TNFi; differences in RMST were 0.02 months (95% CI: −0.08 to 0.013; P = 0.65) and 0.31 months (95% CI: −0.02 to 0.63; P = 0.06), respectively. Patients in the BARI group had 1.00 month (95% CI: 0.14 to 1.86; P = 0.02) longer drug survival to 24 months. There was no difference in drug survival for BARI monotherapy compared with combination therapy, with differences in RMST to 6, 12, and 24 months of −0.19 months (95% CI: −0.50 to 0.12; P = 0.12), −0.35 months (95% CI: −1.17 to 0.42; P = 0.41), and −0.56 months (95% CI: −2.66 to 1.54; P = 0.60), respectively. CONCLUSION: In this comparative analysis, treatment persistence up to 24 months was significantly longer for first‐line BARI compared with TNFi, but the effect size of 1.00 month is not clinically meaningful. There was no difference in persistence for BARI monotherapy versus combination therapy.