Systematic review: the influence of geography and ethnicity in irritable bowel syndrome

Background: Irritable bowel syndrome has been said to be less common in developing countries compared with western populations. In some case series of irritable bowel syndrome from the Indian subcontinent and Africa, the female predominance typical of western patients did not occur. Aim and Methods: A systematic review was performed on Medline, of community prevalence studies of irritable bowel syndrome, chronic constipation and chronic diarrhoea using standardized criteria, with special reference to the effect of geography and ethnicity, and the gender distribution in different countries. Results: There is a wide variation, depending in part on the criteria used and differences in diagnostic practices and health care utilization. No convincing evidence emerged of a difference between east and west. Most series, eastern or western showed a female predominance or no gender difference. Several US studies in communities and specific populations suggest that stool frequency is lower, and the prevalence of constipation higher, among Afro-Caribbean Americans compared with white individuals. Conclusions: Community studies in multi-racial populations are a useful way of assessing possible ethnic differences in the frequency of irritable bowel syndrome, chronic constipation and diarrhoea, and would additionally present opportunities to relate any ethnic differences to dietary and other environmental factors.