High prevalence of perianal Crohn's disease in patients of Indian ancestry.

Abstract

Background: Inflammatory bowel disease (IBD) has traditionally been thought to be uncommon in patients of Indian subcontinent ancestry, however, recently, an increased incidence has been observed, particularly with Westernisation of lifestyles and migration. There is limited data on the phenotype of Crohn's Disease (CD) in this population. We therefore performed a retrospective analysis to compare the difference in demographics, CD location [Montreal Classification: L1 (ileal) L2 (colonic) and L3 (ileocolonic disease)] and the prevalence of perianal CD in patients of Indian ancestry compared with Caucasian patients. Method(s): Patients on biologic therapy for CD were identified through our IBD database. Information on demographics, disease presentation (including perianal disease) and disease behaviour were obtained from medical records. Patients were then stratified based on ethnicity: Caucasian, Indian ancestry, East Asian, Middle Eastern, Mediterranean and other. Patients' demographics and CD behaviour were analysed retrospectively and the prevalence of perianal disease was determined in each group. Analysis was performed using Chi squared and Mann Whitney testing. Result(s): Of the 144 patients with CD on biologic therapy with complete data that were identified, 118 (82%) patients were Caucasians and 17 (12%) patients were of Indian ancestry. The remaining were Middle Eastern (6 patients), Mediterranean (2 patients) and East Asian (1 patient). The majority of patients of Indian ancestry were born in Australia (8 patients) and India (4 patients). The remaining were from Sri Lanka (2 patients), Fiji (2 patients) and England (1 patient). The majority of patients of Indian ancestry were males compared to Caucasian patients (14 patients (82%) vs 62 patients (53%), respectively; p 0.03). The median age of disease onset in patients of Indian ancestry was 28 years (IQR 16:32 years) and 20 years (IQR 14:27 years) in Caucasian patients (p value 0.3). A higher proportion of patients of Indian ancestry had perianal disease compared to Caucasian patients (11(65%) vs 38 (32%), respectively; p value 0.01). There were more Caucasian patients with L3 disease compared to patients of Indian ancestry (62% vs 35% respectively; p value 0.12). The proportion of Caucasian patients with L1 and L2 disease was 16% and 22% respectively. The proportion of Indian ancestry patients with L1 and L2 disease was 24% and 35% respectively. Conclusion(s): In this small population of Crohn's patients on biologic therapy, there was a high incidence of perianal Crohn's Disease in the patients of Indian ancestry. This need to be confirmed in wider population based studies but may suggest different genetic or environmental influences specific to this ethnicity.