A claims-based Markov model for Crohn's disease

Background Crohn's disease is a chronic condition that often presents in early adulthood. Aim To evaluate health care costs and costs per quality-adjusted life year (QALY) for Crohn's disease. Methods A Markov model was developed using administrative claims data for patients aged >= 18 years with >= 3 years of continuous enrolment from 2000 to 2008 and >= 2 Crohn's disease claims. Disease states (remission, mild-moderate, moderate-severe, and severe-fulminant) were defined using the American College of Gastroenterology treatment guidelines criteria. Transition probabilities were calculated from consecutive 6-month periods. Costs were determined from paid claims and QALY utilities were obtained from the literature. The model assumed a 30-year-old patient at the time of entry into the model. Results There were 40 063 patients identified, with a total of 420 773 cycles [remission (197 111; 46.8%), mild-moderate (44 024; 10.5%), moderate-severe (132 695; 31.5%), severe-fulminant (46 925; 11.2%)]. The costs/QALY for remission, mild-moderate, moderate-severe, and severe-fulminant disease states respectively were $2896, $8428, $11 518 and $69 277 for males and $2896, $8426, $22 633 and $69 412 for females. Conclusions Overall, health care costs for patients with Crohn's disease increased with disease severity. Although the probabilities of transitioning from other health states to the severe-fulminant disease state were low, the cost/QALY was high.