Background: We describe the development and evaluation of a new disease-specific instrument, the Irritable Bowel Syndrome Quality of Life Questionnaire (IBSQOL), which was designed for use in patients with irritable bowel syndrome. The IBSQOL measures 10 domains found to be relevant to patients with irritable bowel syndrome: emotional health, mental health, health belief, sleep, energy, physical functioning, diet, social role, physical role, and sexual relations.
Methods: During its development and evaluation, the IBSQOL was administered to over 500 patients with irritable bowel syndrome--two groups of patients from tertiary care centres, three focus groups of 8-12 patients each, and 287 patients in a national irritable bowel syndrome support network. As a control, the IBSQOL was also administered to 37 patients who did not have irritable bowel syndrome but had other gastrointestinal disorders. Statistical analyses to test the reliability and validity of the IBSQOL were performed using Cronbach's alpha coefficient.
Results: Responses from the focus groups indicated that the IBSQOL was easy to complete and did not require too much time to fill out (approximately equal to 25 min). Statistical analyses of the final 30-item version of the IBSQOL demonstrated that it had both adequate validity and reliability (alpha > or = 0.60). A comparison of mean IBSQOL scores of persons with and without irritable bowel syndrome (but with other gastrointestinal conditions) showed no difference between the two groups with irritable bowel syndrome; however, scores for both irritable bowel syndrome groups were considerably lower than for the non-irritable bowel syndrome group, suggesting better health-related quality of life in patients who do not have irritable bowel syndrome. This further demonstrated the validity of the IBSQOL in targeting questions and domains specific to patients with irritable bowel syndrome.
Conclusions: Evaluation of the IBSQOL included testing the questionnaire in a large number of patients, which resulted in a revised and well-constructed instrument that demonstrated both adequate validity and reliability. The IBSQOL is currently being used in large-scale clinical trials to measure changes in quality of life in patients with irritable bowel syndrome following treatment intervention.