P0440 Faecal and plasma zinc as predictors of relapse in quiescent Crohn’s Disease in the Stratifying Crohn’s Using Biomarker Assessment (SCUBA) study

Abstract Background Zinc is an essential trace element playing an important role in immune function, inflammation regulation and intestinal barrier integrity. Deficiency is common in Inflammatory Bowel Disease (IBD). Recent data has shown zinc deficiency is associated with adverse disease specific outcomes in IBD1 and work from our unit has also suggested it a potential predictor of disease course in Crohn’s disease (CD)2. The Stratifying Crohn’s Using Biomarker Assessment (SCUBA) study assessed a number of biomarkers ability to predict relapse in quiescent CD including plasma and faecal zinc. Here we report the performance of these two potential biomarkers. Methods Patients with clinically quiescent CD (Harvey Bradshaw Index ≤3) were recruited prospectively from a single centre over a 2-year period. Faecal calprotectin, quantitative faecal immunochemical test, plasma and faecal zinc were obtained at baseline in addition to routine biochemical work up. Patients over 50 years old were excluded due to overlay with bowel cancer screening programmes as were those with isolated upper gastrointestinal or perianal CD. Patients were followed up for 1 year or until relapse defined by need for escalation of CD related treatment, steroid, surgery or hospitalisation for CD. Results 274 patients were recruited with 216 plasma zinc and 184 faecal zinc samples returned (of which 171 were paired). Median age was 34 years (range 18-49) and123/229 53.7% were female. Median HBI at submission was 1 with median FCP 55µg/g stool and C reactive protein 3mg/l. Median plasma zinc was 11.6 (IQR 10.5-12.6) µmol/L with 54/216 (25.0%) patients deficient at baseline (gender adjusted). Median faecal zinc was 832 (IQR 419-1481) µmol/kg wet weight. 44/229 (19.2%) experienced a relapse during follow up. No association between plasma zinc and faecal zinc was observed (r=0.068, p=0.38). Plasma zinc did not show ability to predict relapse at one year, area under the receiver operating characteristic curve 0.53. Following adjustment for gender, below reference range plasma zinc did not show discriminative value in predicting time to relapse, relative risk (RR) 1.37 (95% CI 0.73-2.56), p=0.33. After adjustment for confounders a RR 0.49 (95% CI 0.21-1.20), p= 0.12 was observed for (log transformed) faecal zinc. Conclusion Previous retrospective studies have reported an association between plasma zinc and time to relapse however this was not observed in our prospective study. Given these finding plasma zinc is unlikely to be of clinical utility with more accurate established biomarkers available. Levels of faecal zinc were noted to be markedly elevated compared to the literature however given the potential for methodological differences further work is required to validate this finding. References 1.Siva S, Rubin DT, Gulotta G, Wroblewski K, Pekow J. Zinc Deficiency is Associated with Poor Clinical Outcomes in Patients with Inflammatory Bowel Disease. Inflammatory bowel diseases. 2017 Jan;23(1)doi:10.1097/MIB.0000000000000989 2.MJ M, S D, C T, et al. A prospective analysis of micronutrient status in quiescent inflammatory bowel disease - PubMed. Clinical nutrition (Edinburgh, Scotland). 2021 Jan;40(1)doi:10.1016/j.clnu.2020.05.010