The epidemiology of inflammatory bowel disease

Background and aims. The inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), are chronic relapsing disorders of unknown aetiology. The aim of this review is to present the latest epidemiology data on occurrence, disease course, risk for surgery, as well as mortality and cancer risks. Material and methods. Gold standard epidemiology data on the disease course and prognosis of patients with inflammatory bowel disease (IBD) are based on unselected population-based cohort studies. Results. The incidence of ulcerative colitis (UC) and Crohn's disease (CD) has increased overall in Europe from 6.0 per 100,000 person-years in UC and 1.0 per 100,000 person-years in CD in 1962 to 9.8 per 100,000 person-years and 6.3 per 100,000 person-years in 2010, respectively. The highest incidence of IBD is found on the Faroe Islands. Overall, surgery rates have been declining over the last decades, partly due to aggressive medical therapy. Among IBD patients, mortality risk is increased by up to 50% in CD when compared to the background population, but this is not the case for UC. In CD, 25 - 50% deaths are disease-specific deaths, e.g. malnutrition, postoperative complications and intestinal cancer. In UC, disease-specific causes of deaths include colorectal cancer (CRC), and surgical and postoperative complications. The risk of CRC and small bowel cancer is increased two-to eightfold among IBD patients. Various subgroups carry increased risk of malignancy, e.g. those with persistent inflammation, long-standing disease, extensive disease, young age at diagnosis, family history of CRC and co-existing primary sclerosing cholangitis. The risk of extra-intestinal cancers, including lymphoproliferative disorders (LD) and intra-and extrahepatic cholangio carcinoma, is significantly higher among IBD patients. Conclusion. In recent years, self-management and patient empowerment, combined with evolving eHealth solutions, has utilized epidemiological knowledge on disease patterns and has been improving compliance and the timing of adjusting therapies, thus optimizing efficacy by individualizing medication in the community setting.