The IBS-36: a new quality of life measure for irritable bowel syndrome

Abstract

OBJECTIVE: We aimed to develop and validate a quality of life instrument for patients with irritable bowel syndrome (IBS). METHODS: Using focus groups, existing questionnaires, and literature reviews, five IBS patients and nine gastroenterologists compiled and pilot tested for content validity a 70-item questionnaire. The questionnaire was then administered to 107 IBS patients, and using these data, the 70-item questionnaire was reduced to 36 questions through statistical and consensus methodology. The IBS-36 questionnaire was tested for construct validity, reliability, reproducibility, and responsiveness using a gold standard of structured interviews by three gastroenterologists, the Medical Outcomes Study Short Form Quality of Life Questionnaire, and the Coping Resource Inventory. RESULTS: The IBS-36 consists of 36 questions scored on a 7-point Likert scale. It has a very high internal consistency (Cronbach’s α = 0.95) and a high test-retest reliability (Spearman’s r = 0.92) and correlates as hypothesized with the Medical Outcomes Study Short Form Quality of Life Questionnaire ( p < 0.001), McGill pain scores ( p < 0.001), and IBS patient-reported sleep, symptom, and pain scores ( ps = 0.030, <0.001, and <0.001, respectively). CONCLUSIONS: The IBS-36 addresses all areas of quality of life affected by IBS and is easy to administer and score. The IBS-36 is a well-validated, condition-specific quality of life measure for IBS patients that is sensitive to clinical intervention and highly correlated with established quality of life measures and patient-reported symptom scores.