Anemia in inflammatory bowel disease: despite declining rates still a remarkable burden

OBJECTIVES: Anemia is a common complication of inflammatory bowel disease (IBD). This study aimed to determine the prevalence of anemia in IBD patients, the factors associated with anemia, and the different types of anemia. METHODS: This retrospective, registry-based study combined data on patients diagnosed with IBD at 18 years of age or older from the IBD quality registry of Helsinki University Hospital and the electronic health record from January 2000 to January 2025. Demographic and clinical characteristics, laboratory test results, and disease phenotype of patients were analyzed. RESULTS: Altogether, 3698 IBD patients were enrolled, of whom 1313 (36%) had Crohn's disease and 2385 (64%) had ulcerative colitis. The prevalence of anemia was higher in patients with more complex disease phenotypes. Anemia occurred in 57% of women and 55% of men during the calendar year of diagnosis. Although the prevalence of anemia decreased steadily after the year of diagnosis, it was still 35% in women and 20% in men 5 years after diagnosis. The prevalence of anemia after the first year was significantly lower in patients diagnosed after 2010 than in patients diagnosed before 2010. CONCLUSION: Anemia is prevalent during the year of IBD diagnosis. Although its rate decreases 5 years after diagnosis, anemia remains common in IBD patients.