OBJECTIVES To examine the cost effectiveness (CE) of certolizumab vs. adalimumab for Crohn's disease. METHODS CE was modeled as a function of time in remission; hospitalizations; dosing; biologic and medical costs; and QALYs. Certolizumab model inputs were imputed/estimated from PRECISE 1/2. Adalimumab inputs came from the every-other-week (eow) and placebo arms of CHARM. Adalimumab and certolizumab baseline characteristics were matched based on sex, prior anti-TNF history, and CDAI. Remission, hospitalizations, and dosage were weighted based on matching. Two comparisons were made: Base Case Model (BCM) 1: adalimumab vs. certolizumab; and BCM2: treatment minus placebo. Hospitalization costs, other medical costs, and utility were derived the literature. Drug costs were based on 2008 WAC. Since no data were available for certolizumab effects on hospitalization, data were imputed from a regression model employing CHARM data. Data were analyzed in a cost-utility framework from a payer perspective. RESULTS In BCM1, adalimumab patients accrued greater expected incremental health utility (0.0072) in the first 26 weeks of therapy vs. certolizumab. The average 26-week remission rates were 37.4% for adalimumab and 24.4% for certolizumab. Drug-related costs for certolizumab totaled $9110, while hospitalization costs and other direct medical costs were $2943 and $6,523. Adalimumab drug-related costs totaled $7704, while hospitalization costs and other direct medical costs were $2224 and $6015. In BCM2, difference in health utility between 1) certolizumab and placebo was 0.0027, and 2) adalimumab and placebo was 0.0066 (adalimumab advantage of 0.0039). The 26-week average NNTs were 6.7 for adalimumab and 14.4 for certolizumab. In BCM1 (vs. PRECISE 2), adalimumab patients were $456 less costly and incurred 0.0061 greater incremental health utility. In BCM2, adalimumab had a 0.0041 incremental advantage. The 26-week average NNTs were 7.02 for adalimumab and 15.96 for certolizumab. CONCLUSIONS These results suggest adalimumab eow maintenance therapy is a dominant strategy vs. certolizumab.