Nationwide prevalence of inflammatory bowel disease in Sweden: a population-based register study.

Background: Regional studies on inflammatory bowel disease (IBD) suggest an increasing prevalence over time, but no nationwide estimate has been published so far.

Aim: To estimate the IBD prevalence in 2010 in Sweden overall, by disease, and in specific patient segments.

Methods: Patients were identified according to international classification codes for ulcerative colitis and Crohn's disease in in-patient care (1987-2010), day surgery and nonprimary out-patient care (1997-2010) in the nationwide Swedish Patient Register.

Results: Requiring two or more diagnoses of IBD in nonprimary care, a total of 61 344 individuals with physician-diagnosed IBD were alive in Sweden in 2010 (mean age 50 years; 51% men), corresponding to a prevalence of 0.65% (95% CI, 0.65-0.66). The prevalence increased with age, and peaked in women at ages 50-59 years and in men at ages 60-69 years. Adding the requirement of IBD as main (vs. main or contributory) diagnosis code, or diagnosis from an internal medicine/gastroenterology/surgery department did not change the prevalence estimate. Prevalence of actively treated disease (defined as two or more IBD-related visits, of which one occurred in 2010, plus at least one dispensed prescription of IBD-related drugs in 2010) was 0.27% (95% CI, 0.27-0.28).

Conclusions: The Swedish nationwide register-based IBD prevalence was higher compared with previous Swedish and international estimates. While prevalence estimates were robust across different case definitions, once two or more visits were required, only about one-third of prevalent patients were drawing resources from specialised care in 2010.