Cost Utility of Adalimumab versus Infliximab Maintenance Therapies in the United States for Moderately to Severely Active Crohn's Disease

Objective: To determine and compare the cost utilities of the tumour necrosis factor (TNF) antagonists adalimumab and infliximab as maintenance therapies for patients in the US with moderately to severely active Crohn's disease. Methods: Maintenance regimens of adalimumab (40 mg every other week) and infliximab (5 mg/kg) were compared using primary data from the CHARM and published data from the ACCENT I clinical trials. Differences in study samples were minimized by matching and weighting baseline characteristics (Crohn's Disease Activity Index score, age and sex) between the patient groups using the primary clinical trial data. Utilization data were estimated from trial data. Unit costs of TNF antagonists (year 2007 values), hospitalizations (year 2006 values), and other medical costs (year 2006 values) were derived from a systematic literature search. Standard gamble-calculated primary data were used to derive health-utility estimates. Data were analysed in a cost-utility framework from a private payer perspective over a 56-week time horizon. Univariate and probabilistic sensitivity analyses were used to explore uncertainty related to the base-case cost-utility analysis. Given the time horizon, costs and effects were not discounted. Results: Adalimumab- and infliximab-treated patients were in remission for 47.2% and 37.1% of the 56-week period, respectively. Hospital admissions were 34-40% lower for adalimumab than for infliximab, based on the model and observed data, respectively. Patients treated with adalimumab accrued greater expected QALYs (0.014; 95% CI 0.000, 0.022) and lower costs (-$US4852; 95% CI -6758, 491) in the first year of therapy than patients treated with infliximab. Compared with infliximab maintenance therapy, adalimumab had lower drug and administration costs, less drug waste, and lower hospitalization rates. Univariate and multivariate probabilistic sensitivity analyses suggested that these results were robust. Conclusions: This analysis suggests that adalimumab maintenance therapy is a dominant strategy versus infliximab maintenance therapy for patients with moderate to severe Crohn's disease. Adalimumab appeared more effective and less costly than infliximab.