Societal costs attributable to Crohn's disease and ulcerative colitis within the first 5 years after diagnosis: a Danish nationwide cost-of-illness study 2002-2016.

Objective: There is little information on cost-of-illness among patients diagnosed with Crohn's disease (CD) and ulcerative colitis (UC) in Denmark. The objective of this study was to estimate the average 5-year societal costs attributable to CD or UC patients in Denmark with incidence in 2003-2015, including costs related to health care, prescription medicine, home care and production loss.Materials and methods: A national register-based, cost-of-illness study was conducted using an incidence-based approach to estimate societal costs. Incident patients with CD or UC were identified in the National Patient Registry and matched with a non-IBD control from the general population on age and sex. Attributable costs were estimated applying a difference-in-difference approach, where the total costs among individuals in the control group were subtracted from the total costs among patients.Results: CD and UC incidence fluctuated but was approximately 14 and 31 per 100,000 person years, respectively. The average attributable costs were highest the first year after diagnosis, with costs equalling €12,919 per CD patient and €6,501 per UC patient. Hospital admission accounted for 36% in the CD population and 31% in the UC population, the first year after diagnosis. Production loss exceeded all other costs the third-year after diagnosis (CD population: 52%; UC population: 83%).Conclusions: We found that the societal costs attributable to incident CD and UC patients are substantial compared with the general population, primarily consisting of hospital admission costs and production loss. Appropriate treatment at the right time may be beneficial from a societal perspective.