Background: Iron deficiency (ID) and anemia in patients with Inflammatory Bowel Disease (IBD) are associated with a reduced quality of life. We assessed the prevalence of ID and anemia in Dutch outpatients with IBD and compared routine ID(A) management among medical professionals to the European Crohn’s and Colitis Organisation (ECCO) treatment guidelines. Methods: Between January and November 2021, consecutive adult outpatients with IBD were included in this study across 16 Dutch hospitals. Clinical and biochemical data were extracted from medical records. Additionally, medical professionals filled out questionnaires regarding routine ID(A) management. Results: In total, 2197 patients (1271 Crohn’s Disease, 849 Ulcerative Colitis, and 77 IBD-unclassified) were included. Iron parameters were available in 59.3% of cases. The overall prevalence of anemia, ID, and IDA was: 18.0%, 43.4%, and 12.2%, respectively. The prevalence of all three conditions did not differ between IBD subtypes. ID(A) was observed more frequently in patients with biochemically active IBD than in quiescent IBD (ID: 70.8% versus 23.9%; p < 0.001). Contrary to the guidelines, most respondents prescribed standard doses of intravenous or oral iron regardless of biochemical parameters or inflammation. Lastly, 25% of respondents reported not treating non-anemic ID. Conclusions: One in five patients with IBD suffers from anemia that—despite inconsistently measured iron parameters—is primarily caused by ID. Most medical professionals treat IDA with oral iron or standard doses of intravenous iron regardless of biochemical inflammation; however, non-anemic ID is often overlooked. Raising awareness about the management of ID(A) is needed to optimize and personalize routine care.

Background Iron deficiency (ID) and anaemia in Inflammatory Bowel Disease (IBD) are associated with reduced quality of life, worse disease outcomes, and an increase in healthcare costs. In the European guidelines, anaemia is listed as one of the treatment goals. The data on the prevalence of anaemia and ID are inconsistent. Therefore, we evaluated the prevalence of ID, anaemia, and potential risk factors in a large Dutch outpatient population. Methods Between January and November 2021, consecutive adult outpatients with IBD, who did not have significant comorbidities associated with anaemia, were included in this study across 16 general, teaching, and academic hospitals within the Netherlands. Besides demographic and clinical data, relevant biochemical parameters such as haemoglobin (Hb), Mean Corpuscular Volume (MCV), iron indices, and inflammatory markers (e.g., C-reactive protein (CRP) and faecal calprotectin (FCP)) were extracted from medical records. Active IBD was defined by either CRP &gt;5mg/L or FCP &gt;150mg/g. ID was defined by ferritin &lt;100µg/L in case of inflammation and &lt;30µg/L in quiescent IBD, or transferrin saturation &lt;20%. The Dutch national reference range was used to define anaemia: Hb &lt;7.5mmol/L or &lt;8.5mmol/L for females and males, respectively. The data were analysed by stratifying patients into Crohn’s Disease (CD) and Ulcerative Colitis (UC) groups, with the latter also including patients with IBD-unclassified (IBDU). Results In total, 2197 patients (1271 CD, 849 UC, and 77 IBDU) were included in the study. The overall prevalence of anaemia, iron-deficiency anaemia (IDA), and ID was: 18.0%, 12.2%, and 43.4%, respectively. The prevalence of all three conditions did not differ between the CD and UC groups (P&gt;0.05). Severe anaemia (Hb&lt;6.2 mmol/L) was observed only in 28 patients. ID was more frequently observed in biochemically active IBD compared with quiescent IBD (70.8% versus 23.9%; P&lt;0.001). Female gender, younger age, low MCV, and a twofold increase in biochemical inflammation were associated with ID development in multivariable analysis: Log2FCP [OR 1.39; 95% CI: 1.29–1.50; P&lt;0.001] and Log2platelets [OR 1.85; 95% CI: 1.16–2.95; P&lt;0.01]. In multivariable analysis, low ferritin and MCV, inflammation, older age, and male gender were associated with a higher risk of anaemia; however, disease location or behaviour did not affect the risk of developing anaemia or ID. Conclusion One in five ambulatory IBD patients presents with anaemia that is primarily caused by ID. Inflammation increases the risk of ID and anaemia regardless of IBD type or disease location. High ID prevalence suggests the need for screening and treatment optimisation.