Diverse Phenotypes, Consistent Treatment: A Study of 30 997 South Asian and White Inflammatory Bowel Disease Patients Using the UK Inflammatory Bowel Disease BioResource.

Background: Studies in the UK and North America have suggested a distinct disease profile in South Asians compared to that of White populations. Disparities in the medical and surgical management of IBD in minority ethnic groups (including Black Americans and Asians) in the US have been shown, while data from Europe, including the UK, have been lacking. This study sought to evaluate South Asian (SA) and White (WH) inflammatory bowel disease (IBD) phenotypes, and to explore treatment approach variations between these cohorts in the UK using the IBD BioResource database.

Design: Differences between WH and SA IBD patients were analysed using demographic, phenotypic and outcome data. Drug utilisation patterns and surgical outcomes were assessed in propensity score-matched (PSM) cohorts with multivariable logistic regression, Cox regression and Kaplan-Meier analysis.

Results: 30,997 eligible patients were included. UC was the predominant disease subtype in SA (p<0.001). SA were younger at diagnosis (p<0.001), had a male preponderance (p<0.001), and were less likely to have a smoking history at diagnosis. The SA CD phenotype differed from WH, with less ileal (SA 30.3%, WH 38.4%, p=0.008) and stricturing (SA 16.9%, WH 25.6%, p<0.001) disease, but more perianal disease (SA 38.5%, WH 32.2%, p=0.009). More SA UC patients had extensive disease (SA 41.7%, WH 34.1%, p<0.001). In PSM cohorts, comparing treatments, there were no differences in 5-aminosalicylate, corticosteroid, thiopurine, anti-TNF or vedolizumab use. Survival analysis in matched cohorts showed no difference in time to surgery (CD) or colectomy (UC), and SA ethnicity was not associated with a difference in risk of surgery/colectomy.

Conclusion: Demographic and phenotypic differences exist between UK SA and WH IBD patients, highlighting distinct ethnicity-related variance, and the need for a research focus on under-represented populations. In comparing matched SA and WH patients, no disparity in medical and surgical IBD therapy in UK healthcare has been demonstrated: treatment is consistent regardless of ethnicity.