Characterization of the alternating bowel habit subtype in patients with irritable bowel syndrome.

BACKGROUND: Due to a wide range of symptom patterns, patients with irritable bowel syndrome (IBS) are often subgrouped by bowel habit. However, the IBS subgroup with alternating bowel habits (IBS-A) has been poorly characterized. OBJECTIVES: (i) To determine a set of bowel habit symptom criteria, which most specifically identifies IBS patients with an alternating bowel habit, (ii) to describe IBS-A bowel symptom patterns, and (iii) to compare clinical characteristics among IBS-A, constipation-predominant (IBS-C), and diarrhea-predominant IBS (IBS-D). METHODS: One thousand one hundred and two Rome I positive IBS patients were analyzed. Three sets of potential criteria for IBS-A were developed and compared by multirater Kappa test. Gastrointestinal, psychological, extraintestinal symptoms, and health-related quality of life were compared in IBS-A, IBS-C, and IBS-D using chi(2) test and analysis of variance (ANOVA). RESULTS: Stool consistency was determined to be the most specific criteria for alternating bowel habits. IBS-A patients reported rapid fluctuations in bowel habits with short symptom flares and remissions. There was a greater prevalence of psychological and extraintestinal symptoms in the IBS-A subgroup compared to IBS-C and IBS-D. No differences were seen between bowel habit subtypes in health-related quality of life. CONCLUSIONS: IBS-A patients have rapidly fluctuating symptoms and increased psychological comorbidity, which should be taken into account for clinical practice and clinical trials.