Anemia classification, prevalence and predictive factors in inflammatory bowel disease

Introduction: Anemia is a common complication of inflammatory bowel disease and serves as an indicator of severe disease. Objective: This study aims to evaluate the prevalence, etiology, predictive factors, and treatment of anemia in patients with inflammatory bowel disease from two tertiary centers. Method: In this retrospective, cross-sectional study, we assessed the frequency of anemia among patients presenting within a specified calendar year (June 1, 2022, to May 31, 2023), focusing on the lowest hemoglobin levels recorded during this period. We collected demographic data, disease activity scores, treatment regimens, inflammatory markers, and laboratory parameters related to iron balance. Clinical disease activity was evaluated using the Crohn's Disease Activity Index and the partial Mayo Score. The World Health Organization's criteria were utilized for anemia classification and severity assessment. Absolute iron deficiency was defined as a serum ferritin level <30 <mu>g/L, while anemia of chronic disease was defined as a ferritin level >100 mu g/L in conjunction with clinical or biochemical evidence of active disease. Results: The study included 400 patients (277 with Crohn's disease and 123 with ulcerative colitis). Among the Crohn's disease patients, 17.7% exhibited complex disease behavior, and 40.7% of the ulcerative colitis patients had extensive colonic involvement. Biological treatments were administered to 75% of the participants. Anemia was identified in 32.5% (130) of the patient cohort, with 57% classified as mild, 35% as moderate, and 8% as severe. In the subset of non-macrocytic anemia (116 patients), iron status data were available for 51% (n = 66). Of these, 73% had iron deficiency anemia, 6% had anemia of chronic disease, and 17% had chronic disease with functional iron deficiency. Anemia predictors included steroid treatment (p<0.001; OR: 4.2), clinical disease activity (p<0.001, OR: 381), and laboratory markers of disease activity (p<0.001, OR: 2.9). Intravenous iron supplementation was administered to 43 patients, while 12 received oral iron supplementation. Conclusion: The findings highlight the high prevalence of anemia, predominantly iron deficiency anemia, among patients with inflammatory bowel disease, which is closely associated with clinical and laboratory markers of disease activity. This study underscores the importance of diagnosis, classification (through assessment of iron balance parameters), and treatment of anemia in patients with inflammatory bowel disease.