First-line tumor necrosis factor inhibitor versus abatacept treatment choice in real-world patients with anticitrullinated protein antibody- and rheumatoid factor-positive rheumatoid arthritis.

Aim: To compare characteristics of patients with anticitrullinated protein antibody-positive (ACPA+) and rheumatoid factor-positive (RF+) rheumatoid arthritis (RA) who initiated abatacept or a tumor necrosis factor inhibitor (TNFi) as a first-line biologic disease-modifying antirheumatic drug (bDMARD), and to identify factors associated with first-line bDMARD selection. Materials & methods: This retrospective cohort study abstracted data for patients with ACPA+/RF+ RA initiating abatacept or a TNFi as a first-line bDMARD between 1 January 2015 and 19 February 2020. Patient characteristics were compared using chi-square/Fisher exact tests (categorical variables) and Wilcoxon tests (continuous variables). Adjusted odds ratios (OR; 95% confidence interval [CI]) of initiating abatacept versus TNFi were estimated using 2-level logistic regression. Results: The analysis cohort included 301 patients who initiated abatacept and 203 patients who initiated a TNFi. Time from RA diagnosis to first-line initiation (>2 years vs <1 year; OR [95% CI] 2.9 [1.4-6.1]), high and moderate disease activity (versus low; 5.0 [1.8-13.9] and 4.2 [1.5-11.6], respectively), and conventional synthetic (cs) DMARD use within 12 months prior to initiation (versus no csDMARD use; 2.0 [1.1-3.6]) were associated with higher odds of initiating abatacept versus a TNFi (all p < 0.05). Patients with Medicare/other insurance had increased odds of initiating abatacept (versus TNFi) as age increased. Baseline ACPA >250 AU/ml was associated with lower odds of initiating abatacept over a TNFi (versus ACPA 20-250 AU/ml; 0.4 [0.2-0.8]; p < 0.01). Conclusion: In this real-world study, patients with ACPA+/RF+ RA were more likely to initiate abatacept over TNFi as a first-line bDMARD if they had delayed first-line bDMARD initiation, high/moderate disease activity, prior csDMARD use, or were of an older age. There is a need for better understanding of treatment selection and to account for these variables in future studies.