Treatment persistence with adalimumab, etanercept, or infliximab in combination with methotrexate and the effects on health care costs in patients with rheumatoid arthritis.

BACKGROUND: Anti-tumor necrosis factor (TNF) biologic agents are effective in treating rheumatoid arthritis (RA). Information on patient persistence with biologic anti-TNF therapies is limited, and the effects of persistence on the costs of therapy are unknown.
OBJECTIVES: The aims of this study were to compare treatment persistence with adalimumab, etanercept, or infliximab in combination withmethotrexate (MTX) and evaluate the effects of persistence on overall health care costs.
METHODS: This retrospective study used data from the PharMetrics managed care administrative claims database. Data from patients with RA who received combination treatment with an anti-TNF agent plus MTX and had > or = 24 months of continuous plan eligibility were collected. The 3 anti-TNF cohorts were adalimumab + MTX (adalimumab group), etanercept + MTX (etanercept group), and infliximab + MTX (infliximab group). Treatment persistence was defined as the number of days between the first and last anti-TNF treatment and was reported as a percentage of the 1-year period after treatment initiation. Costs were compared between patients with treatment persistence rates > or = 80% or <80%. Demographics, comorbidities, disease severity, and RA-related costs were assessed using descriptive statistics. Univariate and multivariate analyses were applied to identify differences in mean persistence between the 3 cohorts.
RESULTS: Data from 1242 patients were included (77.7% female; mean age, 50.0 years). The mean persistence rate in the overall population was 74.6%, and the mean treatment time was 272.3 days. The infliximab group had a higher persistence rate compared with the etanercept and adalimumab groups (78.0% vs 72.8% and 70.8%, respectively; P < 0.005). In all patients combined, those with treatment persistence > or = 80% had higher mean total health care costs compared with those with treatment persistence <80% ($19,271.52 vs $15,598.46; P < 0.001), largely due to higher pharmacy costs. However, nonpharmacy costs were lower in the > or = 80% persistence cohort ($3091 vs $4601; P = 0.015).
CONCLUSIONS: In this population of patients with RA, overall treatment persistence was high, with patients treated with infliximab + MTX having significantly higher persistence compared with those treated with adalimumab + MTX or etanercept + MTX. While pharmacy costs were higher in patients with > or = 80% persistence, nonpharmacy costs were lower.