Inflammatory Bowel Disease in South Asia: Phenotypes, Treatment Escalation, and Long-Term Outcomes: A Prospective Registry-Based Cohort with Six-Year Follow-Up

Inflammatory bowel disease (IBD) prevalence is rising rapidly across South Asia, with characteristics that overlap but do not entirely match those described in Western cohorts. We followed 284 patients with IBD diagnosed at a tertiary gastroenterology service over six years, characterising phenotypic distribution, treatment escalation patterns, and long-term outcomes. Ulcerative colitis accounted for 55.6% of cases, with extensive colitis the most common Montreal extent classification. Crohn's disease (39.4%) showed a distinct phenotypic distribution with high rates of stricturing (33.9%) and penetrating (42.9%) disease at diagnosis. IBD-unclassified accounted for the remaining 4.9%. Cumulative freedom from IBD-related surgery at six years was 92.7% in ulcerative colitis, 76.9% in inflammatory Crohn's disease, 56.2% in stricturing Crohn's disease, and 41.3% in penetrating Crohn's disease. Biologic step-up occurred in 32.8% of patients within 24 months of diagnosis, with strongest independent predictors including penetrating phenotype, stricturing phenotype, steroid dependence within the first year, and treatment delay greater than six months from symptom onset. The findings support structured early phenotyping and biomarker-guided escalation in the South Asian IBD population.