Purpose: Biologics are a new class of drugs used to treat juvenile idiopathic arthritis (JIA), the most common chronic pediatric rheumatic disease. While these agents possess greater effectiveness than standard therapy, they are considerably more costly. The primary study objective was to determine the incremental costs of biologics per additional responder compared to conventional treatment (methotrexate) in JIA.
Method: A separate decision model was created for etanercept, infliximab, adalimumab and abatacept. The study population was polyarticular-course JIA patients with a prior inadequate response or intolerance to disease modifying anti-rheumatic drugs (DMARDs). The effectiveness measure was the proportion of patients achieving a treatment response (disease improvement) defined according to American College of Rheumatology (ACR) Ped 30 criteria. Model inputs were derived from published randomized controlled trials and observational studies. Costs included direct health care costs and parental productivity losses. The analysis was conducted from the societal perspective over a one-year time horizon. Incremental cost-effectiveness ratios with 95% confidence intervals (CIs) and cost-effectiveness acceptability curves were calculated for each biologic agent using probabilistic sensitivity analyses.
Result: Average annual costs, including medications, drug administration, health care provider services and laboratory tests for monitoring, and productivity costs for drugs administered outside the home (abatacept and infliximab) were $18,966, $17,259, $18,654, $14,733 and $952 for etanercept, infliximab, adalimumab, abatacept and methotrexate, respectively. Under base case assumptions, each biologic was more expensive but more effective than the methotrexate comparator. The incremental costs per additional ACR Ped 30 responder at one year (95% CI) were $26,061 (17,070, 41,834), $31,209 (16,659, 66,220), $46,711 (30,042, 75,787), and $16,204 (11,393, 22,608) for etanercept, infliximab, adalimumab, and abatacept, respectively, compared to methotrexate. In a worst case scenario that paired minimum biologic effectiveness with maximum methotrexate effectiveness, the biologic displayed lower efficacy in 14%, 58%, 7%, and 16% of simulations for etanercept, adalimumab, abatacept and infliximab, respectively.
Conclusion: Beneficial therapeutic responses to biologic therapy in patients with JIA come at a high annual cost to payers. Lack of data on health state utilities in this population precluded the calculation of costs per QALY gained. Long-term safety and effectiveness data are required for estimates of cost-effectiveness over the longer durations of treatment typically seen in the pediatric population.
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