Characteristics Associated with Biologic Monotherapy Use in Biologic-Naive Patients with Rheumatoid Arthritis in a US Registry Population

INTRODUCTION The aim of this study was to describe factors associated with initiating a biologic as monotherapy vs in combination with a conventional disease-modifying antirheumatic drug (DMARD) in biologic-naive patients with rheumatoid arthritis (RA) enrolled in the Corrona registry. METHODS First biologic initiations were classified as monotherapy (Bio MT) or combination therapy (Bio CMB). Baseline demographic and clinical characteristics were evaluated. Odds ratios (OR) based on mixed effects regression models estimated the association of covariates and use of monotherapy. Median odds ratios (MOR) based on estimated physician random effects quantified variation in individual physician use of monotherapy. RESULTS Between October 2001 and April 2012, 3,923 previously biologic-naive patients initiated biologic therapy, of which 19.1 % initiated as monotherapy. Baseline characteristics of patients initiating Bio MT and Bio CMB were similar for age, sex, duration of RA, and clinical disease activity index. Significantly higher proportions of Bio CMB initiators had prior conventional DMARD (97.23 vs 85.60 %; P < 0.01) and methotrexate (MTX) use (91.68 vs 71.87 %; P < 0.01) compared with Bio MT initiators. Variation in individual physician use of monotherapy [MOR 1.89; 95 % confidence interval (CI), 1.66-2.23] and use of biologics approved by the United States Food and Drug Administration for monotherapy (OR 1.47; 95 % CI, 1.20-1.81) significantly influenced the odds of initiating Bio MT. Patient history of hepatic disease, neutropenia, and malignancy were associated with increased odds of being prescribed Bio MT. CONCLUSION In addition to regulatory approval for monotherapy and specific pre-existing comorbidities, significant variation in physician use of monotherapy was associated with increased likelihood of initiating Bio MT, independent of patient factors.