An update on the epidemiology of inflammatory bowel disease in Asia.

A rising trend in the incidence and prevalence of inflammatory bowel disease (IBD) in Asia has been recognized for the past two decades. It has been postulated that this phenomenon may be related to the westernization of lifestyles, including changes in dietary habits and environmental changes such as improved sanitation and industrialization. Previously we reported that the incidence and prevalence rates of IBD in Asia were low compared with the West, but there was a notably rising secular trend. In this review, we summarize the recent epidemiological data in Asia, characterize the clinical features, risk factors and genetic susceptibility of Asian IBD patients, and compare these to those of Western IBD patients. In the past decade, the incidence and prevalence of IBD reported across Asia, particularly in East Asia, has continued to increase. Familial clustering is generally uncommon in East Asia but appears to be higher in West Asia. The genetic susceptibilities in Asian IBD patients differ from those of White patients, as NOD2/CARD15 mutations are much less common. The clinical phenotypes and complication rates of Asian IBD resemble the White population in general, but with some differences, including lower surgical rates, higher prevalence of males, and higher prevalence of ileocolonic involvement among East Asian Crohn's disease patients, and a low frequency of primary sclerosing cholangitis among IBD patients in East and Southeast Asia.