Prevalence, incidence, and treatment patterns of fistulizing Crohn disease: A US population-based cohort study

BACKGROUND: Population-based studies for patients with fistulizing Crohn disease (CD), a severe complication of CD, are limited. OBJECTIVE: To report estimates of the prevalence and incidence rates of fistulizing CD in the United States and examine associated treatment patterns among incident cases. METHODS: This retrospective, observational cohort study used a US administrative claims database from January 1, 2016, to December 31, 2019, with at least 365 days' continuous insurance enrollment. The prevalent patient population comprised patients with incident or existing cases of fistulizing CD. Crude, age, and sex-adjusted prevalence and incidence rates of fistulizing CD were estimated. Baseline characteristics, comorbidities, and CD-related medications and medical procedures were examined for patients with fistulizing CD. RESULTS: The overall crude prevalence (prevalent cases: n = 5,082) and incidence rates (incident cases: n = 2,399) between 2017 and 2019 were 25.2 (95% CI = 24.5-25.9) per 100,000 persons and 6.9 (95% CI = 6.6-7.1) per 100,000 person-years, respectively. Age- and sex-adjusted prevalence and incidence rates were 24.9 (95% CI = 24.2-25.6) per 100,000 persons and 7.0 (95% CI = 6.7-7.3) per 100,000 person-years, respectively. Approximately half of all patients with incident fistulizing CD were prescribed biologic therapies within 1 year of an incident fistula diagnosis, with anti-tumor necrosis factor therapies the most widely prescribed biologic class; antibiotic and corticosteroid use was also common. Among the incident cases, approximately one-third of patients required surgery during the follow-up period, most of which occurred within 3 months of the index date. CONCLUSIONS: This study reports age- and sex-adjusted prevalence and incidence rates for fistulizing CD of 24.9 per 100,000 persons and 7.0 per 100,000 person-years, respectively. As a concerning complication of CD, first-year treatment of fistulas in the United States commonly includes anti-tumor necrosis factor therapy, and there is a considerable surgical burden.