Prevalence of irritable bowel syndrome in Japan: Internet survey using Rome III criteria.

OBJECTIVES: We conducted a large-scale Internet survey of 10,000 subjects across Japan to determine irritable bowel syndrome (IBS) prevalence. (J-ROAD: Japanese research of abdominal symptoms for IBS) METHODS: An equal number of male and female subjects, aged at least 20 years, were surveyed by questionnaire. The prevalence of IBS and its subtypes were determined using Rome III criteria, and the results were analyzed for gender- and age-related differences. IBS prevalence was also determined using Rome II criteria for comparison with Rome III criteria results.

RESULTS: IBS prevalence based on Rome III criteria was 13.1%. IBS with diarrhea (IBS-D) subtype accounted for 29% of these cases, IBS with constipation (IBS-C) subtype 24% of cases, and mixed IBS (IBS-M) subtype 47% of cases. IBS-D was more common in men, while IBS-C predominated in women. IBS was most frequently associated with the 20-29 year age bracket, with prevalence decreasing with age. IBS prevalence based on Rome II criteria was 9.8%.

CONCLUSION: IBS prevalence based on Rome III criteria was 13.1%. On the other hand, IBS prevalence based on Rome II criteria was 9.8%. Diagnosis based on these updated criteria may uncover more IBS cases than Rome II criteria.