P391 A not so innocent bystander: The prevalence and burden of anaemia at IBD onset

Abstract

Abstract Background Anaemia is the most common systemic complication of Inflammatory Bowel Disease (IBD). Contemporary studies linking its prevalence with symptom burden at disease onset are limited. We present the prevalence and disability associated with anaemia in a large new onset adult IBD cohort. Methods Demographic, clinical and biochemical indices were collected prospectively in patients referred with suspected IBD between January 2021 - April 2023. Anaemia was defined as haemoglobin (Hb) of <115g/L in women and <130g/L in men. Iron deficiency was defined as Ferritin <30ug/L (<100ug/L if active inflammation – CRP >5mg/L, Faecal Calprotectin [FCP] >200ug/g) or Iron saturations <15%. IBD disk scores were collected in a subgroup of patients. For two groups, non-parametric Mann-Whitney U tests were utilised, with a pairwise Dunn test and holm corrected p values for more than two. Results Hb results were available for 586 patients (182 CD, 170 UC, 234 non-IBD). Of these, an IBD disk score was available for 245 (84 CD, 71 UC, 90 non-IBD). Hb levels were significantly lower in CD than non-IBD (Table 1). Overall, a significantly larger proportion of patients with CD were anaemic than UC (X2 10.2 p=0.001, odds ratio 2.4 [95% CI 1.39-4.16]). Whilst most anaemic patients in both groups were iron deficient, many without anaemia also had demonstrable iron deficiency (Figure 1). In CD, Hb levels were significantly lower in ileocolonic disease than either isolated ileal (median Hb 125vs135.5g/L, p=0.002) or isolated colonic (125vs139g/L, p=0.002). Across IBD, Hb significantly correlated with Harvey Bradshaw Index (n=142, Spearman’s Rho [SR] -0.23 p=0.007), Partial Mayo (n=143, SR -0.23 p=0.006), Simple endoscopic score for CD (n=130, SR -0.29 p<0.001) and FCP (n=314, SR -0.23 p<0.001). Regarding overall disease burden, Hb correlated with overall disability as determined by the IBD disk (n=155, -0.23 p=0.004). Anaemic patients had higher overall disability (total disk score 62.5vs49 p=0.007). Using individual disk domains, those with anaemia had higher fatigue (median 9vs8, p=0.012), disruption of education or work (7vs4, p<0.001), impairment of body image (7vs4, p=0.019) and reduced sexual function (5.5vs1, p=0.004). When compared in a linear regression alongside age, body mass index, ethnicity, IBD type and baseline FCP, Hb was the second strongest predictor of overall disk score (Model fit R=0.515, BMI t=3.05 p=0.003, Hb t=-2.41 p=0.019). Conclusion Anaemia is frequently present at IBD onset, particularly in CD. Nearly half of those without anaemia have demonstrable iron deficiency. Severity of anaemia is associated with overall disease activity but influences symptom burden and disability beyond that which is attributable to mucosal inflammation alone.