An irritable bowel syndrome-specific symptom questionnaire: Development and validation

Background: No self-assessment instruments are available to assess symptoms of irritable bowel syndrome (IBS). Our aim was to develop a disease-specific symptom questionnaire for use in patients with IBS. Methods: Two-hundred-and-thirty-four patients (77% F) with a mean age of 44 years took part in a psychometric evaluation using the previously validated Gastrointestinal Symptom Rating Scale modified for use in patients with IBS (GSRS-IBS). This version was tested against several disease-specific health-related quality of life (HRQL) questionnaires. Items with a high ceiling effect, items that measured a different construct, and items showing high correlation ( > 0.80) to another item were removed. A confirmatory factor analysis was also performed. Results: The final questionnaire included 13 items depicting problems with satiety, abdominal pain, diarrhoea, constipation and bloating. The internal consistency reliability was high, ranging from 0.74 ( pain) to 0.85 ( satiety). The associations between similar constructs in the GSRS-IBS and the various HRQL scores confirmed the construct validity. Pain, bloating and diarrhoea were the symptom clusters that impaired HRQL the most. Conclusion: The GSRS-IBS is a short and user-friendly instrument with excellent psychometric properties.