Epidemiology of inflammatory bowel disease: focus on Asia.

The epidemiology of inflammatory bowel disease (IBD) is changing globally. Incidence and prevalence may have stabilized in high-incidence areas such as North America and Europe but they continue to rise in previously low-incidence areas such as Eastern Europe, Asia, and much of the developing world. This epidemiological shift likely relates to westernization of lifestyle, changes in diet, and improved hygiene as part of socioeconomic development in developing countries. In Asia, UC is more prevalent than CD, although the UC:CD ratio is narrowing in certain areas. Clinical manifestations of IBD in Asia resemble the Western population, but with some differences, including higher prevalence of males and ileo-colonic CD, less familial clustering, lower surgical rates and extra-intestinal manifestations. These differences may relate to time, genetics and environmental factors. Studying the epidemiology of IBD in an area of rapidly increasing incidence may lead to discovery of important etiologic factors associated with disease development.