Rheumatoid arthritis (RA) is a chronic disease that requires long-term treatment to improve or maintain stable disease activity. Tumor necrosis factor inhibitors (TNFi), a class of biologic disease-modifying antirheumatic drugs (bDMARD), are effective at treating symptoms and inhibiting joint progression. Although treatment changes are not recommended in patients with stable disease, health plans have recently enacted formulary changes with higher copayments that could disrupt patient access to TNFis.
To assess the association of formulary copayment changes with real-world treatment patterns, treatment effectiveness, and health care costs among bDMARD-naive patients with RA receiving the TNFi etanercept.
This retrospective observational cohort analysis used the IBM Watson Health MarketScan Commercial Claims and Encounters Database. Adult patients with RA with 6 months of stable etanercept use (no refill gap ≥ 45 days) from January 1, 2013, through December 31, 2015, were selected and the index date was set to the first fill date after the stable-use period. Average etanercept copayment was calculated at the drug-plan level. Copayment change was defined as a monthly increase of at least $40 to account for copayment changes attributable to etanercept wholesale acquisition costs between 2014 and 2015. This amount also corresponded to the 90th percentile of average plan-level changes in etanercept copayments in the database, representing an average change in copayment by a payer. Patients were followed ≥ 12 months before and after the index date to track etanercept treatment changes and ≥ 12 months after a treatment change to track costs after etanercept copayment changes. Etanercept persistence, bDMARD switching, refill gaps, and treatment effectiveness (using a validated effectiveness algorithm) were described for patients with or without copayment change during the 12 months post-index or postchange. We also assessed the mean total of all-cause and RA-related expenditure during the 12-month post-index (or postchange) period.
1,970 stable patients met study inclusion criteria (mean [standard deviation] age: 50.3 [9.5] years; 77.8% female) and were evaluated. Of these, 133 (6.8%) patients had a copayment change ≥$40 during follow-up. Overall, most patients (60.3%) persisted on etanercept for the 12-month follow-up period, while 13.0% switched from etanercept, and 8.1% discontinued (refill gap of ≥ 45 days). Nearly half (48.0%) of all patients were considered effectively treated according to a validated algorithm. Compared with patients without a copayment change, those with a copayment change were more likely to switch biologics (19.5% vs. 12.6%; 
This study was sponsored by Amgen. Bonafede, Manjelievskaia, and Lopez-Gonzalez are employees of IBM Watson Health, which received funding from Amgen to conduct this study. Oko-osi, Collier, and Stolshek are employees and shareholders of Amgen. Gharaibeh was an employee of Amgen at the time of study execution and manuscript drafting. The authors have no other relationships that present a potential conflict of interest. Data pertaining to this study were presented in a poster at the 2018 ACR/ARHP Annual Meeting; October 19-24, 2018; Chicago, IL.
Changing formulary copayment of etanercept was associated with higher switching without difference in costs or health care utilization between copayment and no copayment change groups.