In addition to this, the incidence may be underestimated due to lack of awareness and misdiagnosis. The incidence and prevalence of UC in Australia and New Zealand are similar to that in the West78,86 find more and large population studies in India also shows very similar incidence

and prevalence rates to other Western countries.87,88 The incidence and prevalence of UC is higher than that of CD in the Asia Pacific region, with some exceptions. Level of agreement: a-87%, b-13%, c-0%, d-0%, e-0% Quality of evidence: II-2 Classification of recommendation: B In countries where the overall IBD prevalence is low, UC appears to be more common than CD. In countries where the prevalence of IBD is high, CD tends to be the dominant sub-type.83 Generally, it is thought that in high prevalence areas, the incidence of both diseases may have stabilized but in low prevalence areas, an initial increase in UC incidence is followed by an increase in CD incidence years later.81,83 In the Asia-Pacific

region, where the prevalence is generally low, a higher incidence and prevalence of UC compared to CD was seen in most countries.58,60,76,82,84,89 The temporal trends in Japan show that the incidence ratio of UC and CD has decreased over time.76,82 In New Zealand, the incidence and prevalence of CD is reported to be higher Isotretinoin than that of UC.78 Genetic and environmental factors are involved in the development of UC Level of agreement: a-94%, b-6%, c-0%, d-0%, e-0% Quality of evidence: II-2 Classification of recommendation: selleckchem B It is generally accepted that the pathogenesis of UC is due to a combination of genetic and environmental

factors. Several studies have shown genetic polymorphisms associated with UC in the Asian population90–94 but only a few studies have looked at possible environmental risk factors in the development of UC in order to explain the rising incidence of the disease in this region.95–97 As in the West, some studies have showed that smoking has a protective effect in the development of UC.95,97 Other possible environmental factors associated with UC in the Asian population include a Western diet95 and a high consumption of refined carbohydrates.98 A positive family history probably occurs at a lower rate in UC patients than in the Western population, but is a significant risk factor in the development of UC in the Asia-Pacific region. Level of agreement: a-44%, b-50%, c-6%, d-0%, e-0% Quality of evidence: II-2 Classification of recommendation: B In terms of a positive family history, there appears to be a wide variation among the different studies looking at UC in Asia, with rates ranging from 0.6% to as high as 8%.