P182 Assessing the effect of ethnicity on urinary metabolic profiles in inflammatory bowel disease

Abstract

Introduction Urinary metabolic profiling has been shown to distinguish patients with inflammatory bowel disease (IBD) from healthy controls (HC), and also separate ulcerative colitis (UC) from Crohn's disease (CD) in Caucasian (Cau) cohorts (1). Diet and lifestyle also have an effect on metabolic profiles (2), and these differ in patients from different ethnic backgrounds. Moreover, clinical phenotype varies between Cau and South Asians (SA)(3), however discriminatory metabolites have not been studied in different ethnic populations. The aim of this study was to compare the urinary metabolic profiles of IBD patients and HC from Cau and SA backgrounds. Method Samples from 405 IBD patients (283 Cau and 122 SA) and 137 HC (98 Cau and 48 SA) were analysed by H1NMR spectroscopy. Clinical and dietary data were collected. Orthogonal partial least squares discriminant analysis (OPLSDA) was performed to examine whether there were differences in metabolic data between Cau and SA. R2 (variance), Q2 (quality assessment) and p values (validity) for each model were described. Results The phenotype of SA CD was not significantly different to Cau CD in this cohort. In the SA UC group there was more pancolitis (p=0.051) and less proctitis (p=0.008). There were more vegetarians in the SA group. OPLSDA was able to separate patients with IBD from HC, and also UC from CD, in the Cau cohort, but this separation could not be replicated in SA (negative Q2 values). OPLSDA models also separated SA HC from Cau, and SA CD from Cau CD, but in UC no robust model could be made. Conclusion The separation between Cau and SA HC may reflect differing lifestyles including diet. Cau IBD patients could be separated from HC, and CD from UC, replicating previous studies. SA IBD patients could not be separated from HC which may be due to lower numbers of SA patients in this study, and specifically less CD patients where stronger discriminating models have been shown in Cau in previous studies. In CD, Cau and SA could be separated, but Cau and SA patients could not be distinguished in the UC cohort, possibly suggesting the metabolic milieu in CD is stronger and less influenced by the impact of ethnicity.