Prevalence and Severity of Anemia in a Nationwide Cohort of IBD and Non-IBD Patients

Abstract

Introduction: Inflammatory bowel disease (IBD) is associated with a variety of extra-intestinal manifestations amongst which anemia is the most common and has a significant impact on the quality of life. Our aim was to determine the prevalence and severity of anemia among a nationwide cohort of IBD patients and comparing them to a matched group of non-IBD patients. Methods: We conducted a retrospective cohort study among IBD patients followed in the nationwide Veterans Affairs Healthcare System (VAHS). We used a previously validated IBD cohort for our study. Our study period was from 1st January 2011 to 30th June 2016. We included only those IBD patients who were (1) still being followed up in the VAHS on 1st Jan, 2011, (2) had at least 1 year of FU until censure (death or last recorded visit in the VAHS) and (3) had at least one Hemoglobin (Hb) level checked on or after the date of first IBD medication. A cohort of non-IBD patients was obtained by doing a 1:4 match and patients who had at least 1 visit in the VAHS in 2011 and had at least 1 year of FU from the first recorded visit in 2011 to censure were included. In both IBD and non-IBD groups, the FU time was divided into 30 day intervals and the anemia status was determined as mild, moderate and severe based on the WHO classification for anemia. This anemic category was retained until a different category was found during the following interval. Results: Among the 9517 IBD patients who were included in our final cohort, the majority (91%) patients were male and the mean FU time was 2.33 (1.43) years. 44.9% of patients had an anemic mean lab value in at least one 30 day interval during their FU. In the entire cohort, 2.3% had at least one interval with an anemic mean lab value category of severe, 19.9% had a moderate category, 41.5% had a mild category and 91.0% had a Healthy category. In the non-IBD matched patient pool, amongst a total of 9525 patients, the majority of the patients were male (92.7%) and the mean FU time was 3.35 (1.70) years. 34.6% patients had at least one interval with anemic mean lab value. In the entire control cohort, 1.14% had at least one interval with an anemic mean lab value category of severe, 13.0% had a moderate category, 32.5% had a mild category and 92.3% had a healthy category. Conclusion: In this nation wide cohort of IBD patients, almost half were anemic at some time during their follow up. Both the frequency and severity of anemia was higher in the IBD population versus the non-IBD population.