Biologic disease-modifying drug treatment patterns and associated costs for patients with rheumatoid Arthritis.

Abstract

To assess the influence of biologic treatment patterns on healthcare costs for patients with rheumatoid arthritis (RA) initiating tumor necrosis factor-α (TNF-α) antagonist therapy. Patients with 2 RA diagnoses (International Classification of Diseases, 9th ed, 714.xx), and without psoriasis or Crohn's disease, were identified in a US employer-based insurance claims database. A sample of 2545 was constructed based on an index event of initiating TNF-α antagonist therapy and 30 months of continuous enrollment. Baseline characteristics were assessed in the 6-month pre-index period and treatment patterns were determined during the 12-month post-index period. Medical service and prescription drug costs were analyzed for Months 13-24 using multivariate regression analysis to control for baseline characteristics and time-varying confounding associated with treatment and disease severity. In the first year after TNF-α initiation, 89% used a single TNF-α antagonist; only 9% and 2% had switched TNF-α antagonists or received non-TNF biologic disease-modifying antirheumatic drugs, respectively. Descriptive analyses revealed pairwise differences between groups (p < 0.05) in baseline characteristics (comorbidities, RA-related procedure use, and prescription drug use). Controlling for observed baseline characteristics, costs were greater for those treated with multiple vs single TNF-α antagonists: annual RA-related prescription drug costs ($8,340 vs $7,058; p = 0.012), RA-related healthcare costs ($15,048 vs $13,312; p = 0.008), and total healthcare costs ($26,697 vs $21,381; p < 0.001). In this sample, the majority of patients with RA were treated with a single TNF-α antagonist over the first year on therapy. For those who switched therapy, Year 2 RA-related and total direct healthcare costs were higher, adjusting for claims-based measures of RA disease severity.