Data regarding the health care costs of inflammatory bowel disease (IBD) in the United States are limited. The objectives of this study were to estimate the direct costs of Crohn's disease (CD) and ulcerative colitis (UC) in the United States, describe the distribution of costs among inpatient, outpatient, and pharmaceutical services, and identify sociodemographic factors influencing these costs.

We extracted medical and pharmacy claims from an administrative database containing insurance claims from 87 health plans in 33 states, occurring between 2003 and 2004. We identified cases of CD and UC using an administrative definition. For each case, we selected up to 3 non-IBD controls. Claims were classified as inpatient, outpatient, or pharmaceutical according to Current Procedural Terminology codes or National Drug Codes. Costs were based on the paid amount of each claim. IBD-attributable costs were estimated by subtracting costs for non-IBD patients from those for patients with IBD. Logistic regression was used to identify the sociodemographic factors affecting these costs.

We identified 9056 patients with CD and 10,364 patients with UC. Mean annual costs for CD and UC were 8265and 5066, respectively. For CD, 31% of costs were attributable to hospitalization, 33% to outpatient care, and 35% to pharmaceutical claims. The corresponding distribution for UC was 38%, 35%, and 27%, respectively. Costs were significantly higher for children younger than 20 years compared with adults, but this did not vary substantially by sex or region.

This study demonstrates a substantial economic burden of IBD and can be used to inform health policy.