Published online Jan 21, 2018. doi: 10.3748/wjg.v24.i3.424
Peer-review started: August 28, 2017
First decision: October 10, 2017
Revised: November 15, 2017
Accepted: November 21, 2017
Article in press: November 21, 2017
Published online: January 21, 2018
Processing time: 144 Days and 12.8 Hours
To summarise the current literature and define patterns of disease in migrant and racial groups.
A structured key word search in Ovid Medline and EMBASE was undertaken in accordance with PRISMA guidelines. Studies on incidence, prevalence and disease phenotype of migrants and races compared with indigenous groups were eligible for inclusion.
Thirty-three studies met the inclusion criteria. Individual studies showed significant differences in incidence, prevalence and disease phenotype between migrants or race and indigenous groups. Pooled analysis could only be undertaken for incidence studies on South Asians where there was significant heterogeneity between the studies [95% for ulcerative colitis (UC), 83% for Crohn’s disease (CD)]. The difference between incidence rates was not significant with a rate ratio South Asian: Caucasian of 0.78 (95%CI: 0.22-2.78) for CD and 1.39 (95%CI: 0.84-2.32) for UC. South Asians showed consistently higher incidence and more extensive UC than the indigenous population in five countries. A similar pattern was observed for Hispanics in the United States. Bangladeshis and African Americans showed an increased risk of CD with perianal disease.
This review suggests that migration and race influence the risk of developing inflammatory bowel disease. This may be due to different inherent responses upon exposure to an environmental trigger in the adopted country. Further prospective studies on homogenous migrant populations are needed to validate these observations, with a parallel arm for in-depth investigation of putative drivers.
Core tip: We reviewed the literature on the epidemiology of inflammatory bowel disease (IBD) in migrants and racial groups. Thirty-three studies met the inclusion criteria. Individual studies showed significant differences in incidence, prevalence and disease phenotype between migrants or race and indigenous groups. Only the incidence studies were sufficient in number and comparable for pooled analysis and meta-analysis. There was a trend for higher incidence for ulcerative colitis and lower incidence for Crohn’s disease in South Asian migrants. This review suggests that migration and race influence the risk of developing IBD. This may be due to different inherent responses upon exposure to an environmental trigger in the adopted country.