Epidemiologic survey of ulcerative colitis and crohn's disease in Japan using claim data.

We aimed to clarify the status of ulcerative colitis (UC) and Crohn's Disease (CD), identify the proportion of patients who visited only clinics, and obtain data to support the nationwide survey using a claims database including records of hospital and clinic visits. An epidemiological survey of hospitals and clinics was conducted using a nationwide claims database to estimate the prevalences of UC and CD in the same year as the nationwide survey. The proportion of patients who visited only clinics was calculated. Patients with UC were divided into two groups: those who visited only clinics and those who visited hospitals. UC and CD prevalence rates per 100,000 population were 227.9 and 58.2, respectively. Approximately 35% and 12% of patients with UC and CD, respectively, visited only clinics. Multivariate logistic regression analysis adjusted for patient background showed that patients who visited only clinics were older, had milder comorbidities, and incurred lower UC treatment costs than patients who visited hospitals. Epidemiological surveys using the claims database revealed that 35% of patients with UC visited only clinics. Therefore, the actual prevalence rates of patients with UC are expected to be higher than those reported in the nationwide survey, which included only hospital visits.