EpidemIBD: rationale and design of a large-scale epidemiological study of inflammatory bowel disease in Spain.

Background: Inflammatory bowel disease (IBD) is associated with a considerable burden to the patient and society. However, current data on IBD incidence and burden are limited because of the paucity of nationwide epidemiological studies, heterogeneous designs, and a low number of participating centers and sample size. The EpidemIBD study is a large-scale investigation to provide an accurate assessment of the incidence of IBD in Spain, as well as treatment patterns and outcomes.

Methods: This multicenter, population-based incidence cohort study included patients aged >18 years with IBD (Crohn's disease, ulcerative colitis, or unclassified IBD) diagnosed during 2017 in 108 hospitals in Spain, covering 50% of the Spanish population. Each participating patient will attend 10 clinic visits during 5 years of follow up. Demographic data, IBD characteristics and family history, complications, treatments, surgeries, and hospital admissions will be recorded.

Results: The EpidemIBD study is the first large-scale nationwide study to investigate the incidence of IBD in Spain. Enrollment is now completed and 3627 patients are currently being followed up.

Conclusions: The study has been designed to overcome many of the limitations of previous European studies into IBD incidence by prospectively recruiting a large number of patients from all regions of Spain. In addition to epidemiological information about the burden of IBD, the 5-year follow-up period will also provide information on treatment patterns, and the natural history and financial burden of IBD.