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13. Prevalence of anemia in patients with inflammatory bowel disease during the first ten years from diagnosis – results from a population-based inception cohort, the IBSEN Study

M.L. Hoivik1, W. Reinisch2, M. Cvancarova3, B. Moum1, 1Oslo University Hospital, Gastroenterology, Oslo, Norway, 2Medizinische Universität Wien, Klinische Abt. Gastroenterologie & Hepatologie, Wien, Austria, 3University of Oslo, Department of Biostatistics, Oslo, Norway


The reported prevalence of anemia in inflammatory bowel disease (IBD) varies substantially depending upon the definition of anemia and the patient population considered (hospitalized vs. outpatients). Anemia in IBD is associated with a reduced quality of life and necessitates adequate monitoring and treatment of underlining often multi-factorial causes. This is the first study to prospectively determine the prevalence of anemia at diagnosis and at 1, 5 and 10 year follow-up in a population-based inception cohort of IBD patients.


Patients with newly diagnosed ulcerative colitis (UC) or Crohn's disease (CD) were included at baseline in a population-based, prospective cohort. Prescheduled follow-up was performed at 1, 5 and 10 years after diagnosis. In addition to comprehensive clinical examinations, blood samples, including hemoglobin (Hb), were drawn at each visit. Hb levels were categorized as anemia according to the anemia definition from the World Health Organisation (Hb <12 g/dL in women and <13 g/dL in men). Included in this analysis were patients from whom at least the baseline Hb level was available.


In total, 756 patients (UC, n = 519 and CD, n = 237) were included in the cohort from whom 690 subjects (91%) qualified for the analysis. More patients with CD compared to UC presented with anemia at diagnosis (21% and 50%, respectively, p < 0.001).

The proportion of patients with anemia decreased during the disease course in both diagnostic groups. At every visit the prevalence of anemia was higher in CD than in UC patients, but the absolute difference decreased over the years. The results were unchanged in a sensitivity analysis including only patients in whom we had Hb data from all four visits (data not shown). Women with CD had a higher prevalence of anemia than men with CD at the ten year follow-up (20% vs 7.3%, p = 0.018) (Figure 1).

Figure 1. Prevalence of anemia by diagnsosis and gender.

Table 1. Prevalence of anemia at diagnosis, 1, 5 and 10 years follow up.
 UC (n = 465)CD (n = 225)p-value*
Diagnosis20.9% (97/465)49.8% (112/225)<0.001
1 year14.2% (46/325)20.6% (37/180)0.063
5 years9.9% (33/333)16.9% (30/117)0.021
10 years7.2% (23/321)13.2% (22/162)0.022
*CD vs. UC.


Anemia is more common in CD than in UC. The prevalence of anemia decreases during the disease course. Women with CD are at high risk for anemia even after ten years of disease.