High rates of inflammatory bowel disease (IBD) are reported in children of South Asian (SA) descent in some western countries. This population-based study describes the incidence and clinical course of IBD in SA children compared to non-South Asian (NSA) children in New Zealand (NZ).
Children (≤15 years) with new-onset IBD presenting to a centralized tertiary referral center in Auckland, NZ from 2010-2020 were identified. Disease phenotype, clinical characteristics, response to exclusive enteral nutrition, clinical remission rates at 3 and 12 months, biologic use, corticosteroid exposure and disease complications were compared by ethnicity; IBD incidence was calculated.
There were 127 (26 SA; 101 NSA) children with Crohn’s disease, 41 (10 SA; 31 NSA) with ulcerative colitis and 10 (3 SA; 7 NSA) with IBD-unclassified. IBD incidence in SA and NSA children was 14.1 per 100,000 and 4.3 per 100,000 respectively (P<0.001). IBD incidence increased by 5.6% per year (p=0.022), due to a greater rise in incidence in SA (SA 16.8% per year p=0.015, NSA 4.5% per year, p=0.317). At presentation, SA children had worse biochemical parameters, severe colitis and vitamin D deficiency. SA children had lower rates of remission following exclusive enteral nutrition (28.5% vs 65.0% p<0.001) or biologic induction (35.7% vs 70.8%, p=0.020), at 3-month (35.3% vs 69.8% p<0.001) and 12-month follow-up (29.4% vs 55.0%, p=0.005). No significant differences were found in disease location or corticosteroid burden.
Increasing incidence of IBD was disproportionately represented by SA children with more severe disease and lower remission rates following exclusive enteral nutrition or biologic therapy.

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