Prevalence of Irritable Bowel Syndrome in East Asia: Are There Differences Between Countries?

c 2023 The Korean Society of Neurogastroenterology and Motility J Neurogastroenterol Motil, Vol. 29 No. 2 April, 2023 www.jnmjournal.org Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders seen by primary care physicians. The worldwide prevalence of IBS is reported to be over 10%, but there are differences in the prevalence of IBS across countries; its prevalence is reported to be 17.5% in Latin America, 9.6% in Asia, 7.1% in North America and Europe, and 5.8% in the Middle East and Africa. Also, the prevalence of IBS subtypes (ie, constipationpredominant IBS [IBS-C], diarrhea-predominant IBS [IBS-D], mixed IBS [IBS-M], and unclassified IBS [IBS-U]) also differs by country or ethnicity. In this issue, the prevalence of IBS were evaluated using internet-based survey in the 3 East Asian countries, Japan, China, and South Korea. These 3 countries have some similarities in ethnicity, diet, and experiencing rapid socioeconomic change, while they have their own unique cultures. Interestingly, the overall prevalence of IBS was quite different; IBS prevalence in China was statistically lower (6%) than those in Japan and South Korea (15% and 16%, respectively.) In terms of IBS subtypes, IBS-M was the most common subtype, followed by IBS-D, IBS-C, and IBS-U in the overall analysis (6.01%, 2.76%, 2.07% and 1.74%, respectively). IBS-M was the most common subtype in all 3 countries; however, the second most common subtype was IBS-D in Japan, IBS-C in China, and IBS-U in South Korea. Furthermore, the IBS prevalence was significantly higher in men, especially in the case of IBS-D. As females are reportedly more susceptible to IBS, verification of the results of this study is essential. Great caution is needed in interpreting the results of the study. Above all, in this study, nationally representative sampling of each country was not performed. This study could be highly biased as it is based on an internet-based questionnaire of the volunteers. Considering the nature of the internet surveys, it is important to provide the percentage of respondents out of the total number of respondents requesting a survey by country. For example, it is possible that Chinese IBS patients responded less, whereas Korean and Japanese IBS patients responded more actively. For the results of this study to be confirmed, it is necessary to determine what percentage of the response rate was in the 3 countries and whether there was a difference in the response rate. Also, the high prevalence of IBS in men, which is contrary to previous studies, may also be influenced by differences in response rates by sex. Furthermore, as the authors mentioned, as China is a large country and each region has different cultures and dietary habits, selection bias can be noticeable when a JNM J Neurogastroenterol Motil, Vol. 29 No. 2 April, 2023 pISSN: 2093-0879 eISSN: 2093-0887 https://doi.org/10.5056/jnm23042 Editorial Journal of Neurogastroenterology and Motility