Familial aggregation of inflammatory bowel disease in India: Prevalence, risks and impact on disease behavior

Background/Aims: Information about familial aggregation of inflammatory bowel disease (IBD) in Asia is limited. We aimed to analyze the prevalence and risk of familial IBD in an Indian cohort and compare familial and sporadic cases. Methods: Familial IBD cases were identified from a large prospectively maintained IBD registry. The prevalence of IBD in first-and second-degree relatives of index cases was evaluated. The disease behavior was compared to that of sporadic cases. Results: Total 3,553 patients (ulcerative colitis [UC], 2,053; Crohn's disease [CD], 1,500) were included. Familial IBD was noted in 4.13% of CD and 4.34% of UC patients. Family history was commoner in pediatric group (<18 years) (P=0.0002; odds ratio [OR], 2.8; 95% confidence interval [CI], 1.6-4.8). Majority had paternal transmission (UC, 67.42%; CD, 70.97%). Concordance of disease type was higher in UC (79.7%) compared to CD (37.1%). Familial IBD was associated with higher cumulative relapse rate (CD, P<0.001; UC, P<0.001), higher cumulative rate of surgery (CD, P<0.001; UC, P<0.001) and higher rate of biologic use (CD, P=0.010; UC, P=0.015). Pan-colitis was higher in familial UC (P=0.003; OR, 1.935; 95% CI, 1.248-3.000). Fistulizing disease was commoner in familial CD (P=0.041; OR, 2.044; 95% CI, 1.030-4.056). Conclusions: The prevalence of familial IBD in India appears comparable to rest of Asia but lower than the West. It is associated with a younger age of onset, higher incidence of pan-colitis in UC and fistulizing complications in CD. Familial IBD has higher cumulative relapse, surgery and biologic use rates. Hence, family history of IBD could have important prognostic implications. (Intest Res 2019;17:486-495).