The epidemiology of inflammatory bowel disease in Asia and Asian immigrants to Western countries.

Inflammatory bowel disease (IBD), which comprises Crohn's disease and ulcerative colitis, is an idiopathic inflammatory condition of the gastrointestinal tract. The incidence and prevalence of IBD are rapidly increasing worldwide, particularly in newly industrialized regions such as Asia. Although a large medical armamentarium is available for treating this chronic disease, IBD imposes a marked global disease burden. To understand the complex etiopathogenesis of this condition, it is important to consider the rapidly changing trends in its epidemiology in Asia. During the past few decades, the incidence and prevalence of IBD have significantly increased in both Asian countries and Asian immigrants in Western countries. In this review, we aimed to study and update the epidemiology of IBD in diverse Asian regions and among Asian immigrants in North America and Europe. Moreover, we highlighted that this population exhibits a unique disease phenotype, such as male predominance and high frequency of perianal fistula in Crohn's disease. Also, a different disease phenotype including more complicated disease such as perianal complications was noted in Asian Americans and Asian Europeans.