Prevalence of Irritable Bowel Syndrome in Japan, China, and South Korea: An International Cross-sectional Study.

Background/aims: Symptoms of irritable bowel syndrome (IBS), a common gut-brain interaction disorder, deteriorate patients' quality of life and increase medical needs; therefore, IBS represents a significant global burden. The estimated global prevalence is approximately 10%; however, accumulated evidence shows international heterogeneity. In this study, we have described and compared the prevalence of IBS in 3 East Asian countries: Japan (Tokyo and Fukuoka), China (Beijing), and South Korea (Seoul).

Methods: We conducted an internet-based cross-sectional survey of the urban population aged > 20 years in the abovementioned countries. We recruited equal numbers of age- (20s-60s) and sex-matched participants (3910 residents). IBS was diagnosed according to the Rome III criteria, and the subtypes were analyzed.

Results: The overall prevalence of IBS with 95% CI was 12.6% (11.6-13.7); the prevalence was significantly different across Japan, China, and South Korea (14.9% [13.4-16.5], 5.5% [4.3-7.1], and 15.6% [13.3-18.3], respectively) (P < 0.001). Furthermore, 54.9% of patients were male. IBS-mixed was the most prevalent subtype; the prevalence of other subtypes varied.

Conclusions: The overall prevalence of IBS in the 3 countries was slightly higher than the global prevalence, and it was significantly lower in China than in Japan and South Korea. IBS prevalence was the highest and lowest among individuals in their 40s and 60s, respectively. Male individuals had a higher prevalence of IBS with diarrhea. Further studies are needed to elucidate the factors associated with this regional heterogeneity.