Abstract
Anemia is a common manifestation of inflammatory bowel disease (IBD), but it remains unclear whether anemia is associated with the development of IBD. We assessed the risk of developing IBD in anemic patients, and stratified the results with respect to their hemoglobin concentrations. A population-based study was conducted using the National Healthcare Insurance Service database in South Korea. We included individuals over 20 years’ old who participated in the national health screening program in 2009 (n = 9,962,064). Anemia was defined as a hemoglobin level less than 13 g/dL in men and less than 12 g/dL in women. We compared the rate of newly diagnosed IBD in anemic patients and non-anemic individuals. Newly diagnosed IBD was identified using both the ICD-10 medical code and specialized V codes for rare intractable diseases in South Korea. During the mean follow-up period of 7.3 years, the incidences of CD and UC in anemic patients were 2.89 and 6.88 per 100,000 person-years, respectively. The risk of CD was significantly higher in anemic patients than in non-anemic individuals [adjusted hazard ratio (aHR), 2.084; 95% confidence interval (CI), 1.769–2.455]. The risk of CD development was inversely proportional to the hemoglobin concentration. A J-curve relationship was observed between age and the risk of CD in anemic patients. The risk of CD in male anemic patients was significantly higher than that in female anemic patients (aHR, 1.432 vs. 1.240, respectively). By contrast, there was no statistically significant difference in the risk of developing UC in anemic and non-anemic individuals (aHR, 0.972; 95% CI, 0.880–1.073). This work indicates that anemia is related to the development of CD, and this risk was inversely proportional to the hemoglobin concentration.
Highlights
Anemia is defined as a hemoglobin concentration less than 13 g/dL in men and less than 12 g/ dL in women according to World Health Organization (WHO) standards [1]
We investigated the incidence and risk of Inflammatory bowel disease (IBD) in anemic patients using a large-scale, population-based cohort of nearly 10 million Korean patients
The incidence and risk of Crohn’s disease (CD) were significantly higher in the anemic group than the non-anemic group, but this association was not observed for ulcerative colitis (UC)
Summary
Anemia is defined as a hemoglobin concentration less than 13 g/dL in men and less than 12 g/ dL in women according to World Health Organization (WHO) standards [1]. Anemia can be caused by a variety of etiologies such as iron deficiency, chronic diseases, vitamin B12 or folate deficiency, and genetic factors. Anemia is a known risk factor for cardiovascular diseases, dementia, and chronic medical illness, leading to an increase in all-cause mortality [2,3,4,5]. IBD is a chronic inflammatory gastrointestinal disorder that involves complex interactions among genetic, environmental, immunological, and microbiological factors. The incidence of IBD in South Korea has been increasing, which causes higher medical and socioeconomic burdens [6]. IBD patients experience various systemic manifestations related to intestinal inflammation during disease progression. Anemia is a prevalent extraintestinal manifestation of IBD, especially for patients with CD. Malabsorption, malnutrition, and micronutrient deficiency cause anemia in patients with IBD. Gastrointestinal bleeding can induce or aggravate anemia [7, 8]
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