Objective: To evaluate whether initiation of etanercept therapy among patients with rheumatoid arthritis (RA) impacts use of co-therapy with methotrexate or prednisone, and to describe etanercept dosing dynamics compared to product monograph in the Canadian real-world setting. Methods: A retrospective cohort study was conducted using claims-level data from IQVIA Private Drug Plan database, Ontario Public Drug Plan database and Régie de l'assurance maladie du Québec database. Bio-naïve RA patients initiating etanercept between July 2014 and June 2015 were identified and their claims for methotrexate or prednisone were analyzed. Utilization of methotrexate or prednisone was calculated as average weekly dose in milligrams, and compared in the 6 months pre-initiation versus 12 months post-initiation of etanercept. Weekly etanercept dosing of each patient was calculated and analyzed to determine whether patients had at least 20% higher or lower average dose than monograph recommended dose (50 mg/week), and were then flagged as above-monograph or below-monograph, respectively. Results: A total of 2876 patients with RA (66% female, 76% aged 18-65) were included; 62% (n = 1,140) used methotrexate and 27% used prednisone (n = 498) both pre- and post-initiation of etanercept. In methotrexate patients, the average weekly dose dispensed was 25.4 mg in the 6 months pre-etanercept, and 25.0 mg in the 12 months post-etanercept initiation (p = .5282). In prednisone patients, the average weekly dose dispensed reduced from 122.6 mg pre-etanercept to 107.1 mg post-etanercept initiation (p = .2173). Among patients who were already on methotrexate or prednisone, after initiating on etanercept 16% (n = 213) and 34% (n = 254) of patients stopped methotrexate and prednisone, respectively. When compared to the recommended dose, 12% (n = 168) of patients were below-monograph and 7.1% of patients were above-monograph during their first year of etanercept therapy. Average etanercept dosing was consistently lower than product monograph during the follow-up year. Conclusions: Patients had a modest but not statistically significant decrease in prescribed doses of co-therapy with methotrexate and prednisone when etanercept was added to patients' therapy. In addition, 12-14% of patients stopped their co-therapy with methotrexate or prednisone. Further study is needed to understand the impact on patient outcomes and safety.
Keywords: Ankylosing spondylitis; etanercept; immune-mediated inflammatory disease; methotrexate; prednisone; real-world evidence; rheumatoid arthritis.