Phenotypic Characterisation of Inflammatory Bowel Disease in South Asians in the United Kingdom: Insights into a Shifting Landscape

Abstract

Purpose: The aetiology of inflammatory bowel disease (IBD) remains elusive; a complex interplay of genetic, environmental and immunological influences. The increasing incidence of IBD in developing countries and immigrant populations appears to outpace what genetic influences alone could instigate and may provide valuable insights into aetiology. There is a relative dearth of literature on the phenotypic characteristics of South Asian immigrant populations. The aim of our study was to define the clinical phenotype of IBD in South Asians living in North-West England. Methods: We conducted a retrospective study of 102 patients of South Asian origin attending IBD clinics at our hospital. Clinical data including demographics, disease characteristics (Montreal classification), treatment and blood results were obtained using electronic case records. Results: Of 102 patients reviewed, 54 were male. The median age was 38 years (range 16-80) and mean disease duration was 9.4 years. Seventy-three patients had ulcerative colitis (UC) and 29 had Crohn's disease (CD). Five patients were current or ex smokers (4.9%). Seventeen patients had extra-intestinal manifestations of IBD (16.7%). Of UC patients 35 had pancolitis, 33 left sided disease and 5 had proctitis. Of patients with CD, 3 had ileal disease, 10 colonic disease and 16 had ileocolonic disease. Five CD patients had stricturing disease, 10 had penetrating disease (6 also stricturing) and 14 had non-penetrating, non-stricturing disease. Perianal disease was noted in 3 at diagnosis and 5 subsequently developed it. Eighty patients received steroids, topical steroids (29), 5-ASA (96), topical 5-ASA (30), azathioprine (55), 6-mercaptopurine (4), cyclosporine (2), methotrexate (9), infliximab (20) and adalimumab (9). Fifty-seven patients received at least one immunomodulatory therapy with the median time to use being 12 months (range 0-276 mo). Thirteen patients (7 CD, 3 UC) required surgery (3 total colectomy, 10 subtotal). Mean time to surgery was 4 years (range 0-13 years). Seventeen patients had disease progression leading to Montreal reclassification (median time 60 months; range 1-216 mo). Conclusion: We noted a higher prevalence of UC with a predominance of pancolonic disease and a significant proportion of CD with penetrating or stricturing disease. The majority of patients required immunomodulatory therapy with the median time to use being only 12 months, suggesting a relatively more aggressive disease course. Epidemiologic insights from such populations may provide further clues in defining an aetiological paradigm for IBD and should form an important area of further research. A case control study exploring differences is underway at our institution.