Multicenter observational study on functional bowel disorders diagnosed using Rome III diagnostic criteria in Japan

The Rome III diagnostic criteria had been used to diagnose functional gastrointestinal disorders (FGIDs) world wide, and functional bowel disorders (FBDs) including irritable bowel syndrome (IBS) have recently attracted the attention of Japanese physicians. However, there have been few reports on the prevalence of FBDs diagnosed by the Rome III diagnostic criteria. The aim of this study was to determine the prevalence of FBDs diagnosed according to the diagnostic criteria of Rome III in Japan. All patients who were booked for colonoscopy were enrolled from eight institutions in Japan. This study was a prospective observational study in the period from April 2013 to December 2013. Patients filled out FGID questionnaires of Rome III when they were waiting for colonoscopy. Data for 1200 patients who underwent colonoscopy were analyzed. A total of 547 patients (45.6%) were diagnosed with FBDs. Out of those patients, 9.1% had IBS. According to the Rome III diagnostic criteria, 134 patients (11.2%) had functional bloating (FB), 73 (6.1%) had functional constipation (FC), 40 (3.3%) had functional diarrhea (FD), and 191 (15.9%) had unspecified functional bowel disorder (UFBD). Patients with FBDs had significantly higher rates of almost all symptoms (abdominal pain, hard or lumpy stools, loose or watery stools, and bloating) than those in the controls. In Japan, the prevalence of FBDs and IBS is high, similar to that in the US. Many patients with FBDs have multiple symptoms.