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

Abstract

We aimed to develop and validate a quality of life instrument for patients with irritable bowel syndrome (IBS). 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. The IBS-36 consists of 36 questions scored on a 7-point Likert scale. It has a very high internal consistency (Cronbach's alpha = 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). 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.