Subtypes of irritable bowel syndrome on Rome III criteria: a multicenter study.

Objective: The aim of this study was to explore the distribution and clinical characteristics of four subtypes of irritable bowel syndrome (IBS) based on Rome III criteria in Chinese.

Methods: A total of 754 consecutive IBS outpatients from three tertiary hospitals in China were included. Diagnostic criteria were based on Rome II or Rome III.

Results: Among 754 outpatients, 510 (67.6%) patients met the Rome II criteria, 735 (97.5%) patients met the Rome III criteria and 492 (65.3%) patients met both sets of criteria. Among 735 patients who met the Rome III criteria, 66.3% had IBS with diarrhea (IBS-D), 14.7% had IBS with constipation (IBS-C), 4.2% had mixed IBS (IBS-M) and 14.8% had unsubtyped IBS (IBS-U). Most of the IBS-D, IBS-C and IBS-M patients based on the Rome III criteria matched the diarrhea-predominant IBS, constipation-predominant IBS and alternating IBS based on the Rome II criteria, respectively. Among IBS-U patients, 57.0%, 33.3% and 9.7% had constipation-predominant IBS, diarrhea-predominant IBS and alternating IBS, respectively. For IBS-M, the frequencies of bowel movements were stable in 48.4% patients and variable in 51.6% patients. Defecation urgency and straining were most frequent in IBS-M and least frequent in IBS-U patients than other subtypes. About 77.2% of IBS-U patients had abnormal stool frequency (< 3 times/week or > 3 times/day).

Conclusions: The Rome III criteria are more sensitive and practical in diagnosing IBS. IBS-D is the most frequent subtype, which is followed by IBS-U, IBS-C and IBS-M. IBS-U is a new subtype, which warrants further studies.