Cost-effectiveness of immunomodulators versus infliximab for adults with moderate-to-severe ulcerative colitis.

Abstract

PURPOSE: To estimate and compare cost-effectiveness between infliximab and immunomodulators in the United States (US) for adult patients with moderate to severe ulcerative colitis. METHODS: A Markov decision model was constructed based on the Active Ulcerative Colitis Trials (ACT 1 and 2) comparing infliximab versus immunomodulators, supplemented with published outcomes data for patients with ulcerative colitis. The study perspective was from that of a US commercial payer. In terms of disease state, the Markov model classified patients as either experiencing 1) remission; 2) mild symptoms; 3) moderate to severe symptoms; 4) moderate to severe symptoms leading to colectomy; 5) and three post-surgical states based on time following surgery. The model was based on weekly cycles over a 10-year period. Data for effectiveness measured by clinical response were based on published analyses of ACT 1 and 2 for infliximab and immunomodulators, published quality of life estimates for each health state, costs, and surgical outcomes data for patients with ulcerative colitis. A systematic review of published studies was conducted to estimate rates for post-surgical complications. Eligible studies included those evaluating ulcerative colitis or studies including multiple conditions but reporting results by condition. Post-surgical complications were assessed as those occurring <30 days, <6 months, and >6 months following surgery. Costs were measured by therapy (from 2010 US wholesale acquisition costs) and hospitalization costs (from the Health Care Utilization Project database of hospitalizations in civilian acute care institutions throughout the US). Those stays with a diagnosis of colectomy were selected. Probabilistic sensitivity analysis was conducted using a Monte Carlo simulation with distributions for efficacy, utilities, and cost of hospitalization. A societal discount rate of 3% was used in primary analysis for both cost and effect. The results are presented in terms of cost per quality-adjusted life years (QALYs). RESULTS: The estimated mean (SD) costs over the 10 year period for infliximab and immunomodulators was $379,504 (25,258) and $354,685 (31,929), respectively. The number of QALYs for infliximab was 6.12 (1.67) and 5.43 (1.63) for conventional immunomodulators. With immunomodulators considered baseline therapy, the incremental cost-effectiveness ratio to use infliximab was $35,970. Results from the simulation indicated that infliximab was a dominant therapy in 22% of the simulations, and was cost-effective in 35.5% of the simulations when the threshold value is $65,000 per QALY. Cost-effectiveness acceptability curves indicated that infliximab was most likely to be cost-effective when willingness to pay per QALY exceeded approximately $30,000. CONCLUSIONS: Infliximab was more effective and expensive than immunomodulators. Thus, differences in willingness to pay may lead payers to favor one medication over the other. This analysis suggests that the use of infliximab represents an acceptable incremental increase in costs but at a higher effectiveness. The incremental cost-effectiveness is below acceptable thresholds commonly used to classify products as being cost-effective.