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.