Population-based incidence and prevalence of inflammatory bowel diseases in Milan (Northern Italy), and estimates for Italy

OBJECTIVE A reliable measure of the burden of inflammatory bowel diseases (IBDs), including ulcerative colitis and Crohn's disease, are essential to monitor their epidemiology and plan appropriate health services. METHODS This is a population-based study carried out in the Milan Agency for Health Protection. Incident and prevalent cases were identified according to specific codes in hospital discharges and copayment exemptions. Age-standardized incidence rates were computed for 2015-2018 and yearly rates from 2010 to 2018, as well as annual prevalence and prevalence on 31 December 2018. Incidence and prevalence estimates for Italy were also produced. RESULTS During 2015-2018, 3434 citizens had an IBD diagnosis, 2154 (62.7%) ulcerative colitis and 1.280 (37.3%) Crohn's disease. Age-adjusted incidence rates were 15.3 [95% confidence interval (CI), 14.7-16.0] for ulcerative colitis and 9.4 (8.9-9.9) for Crohn's disease. Incidence was stable during 2010-2018 for both diseases. On 31 December 2018, there were 15 141 prevalent patients, corresponding to a proportion of 442.3 every 100 000 inhabitants/year (95% CI, 435.6-449.8). Prevalence proportion has increased to around +10% per year from 2010 to 2018. Projections for Italy assessed the burden of IBD in more than 15 000 new cases/year (55% ulcerative colitis) and around 260 000 prevalent cases (62% ulcerative colitis). CONCLUSIONS The exploitation of administrative data provides reliable and up-to-date measures of the burden of disease. Incidence of IBDs is stable while prevalence notably grows. The burden of IBDs and the consequent need for care and follow-up is going to increase in the future.