Development and psychometric testing of the Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS)

BACKGROUND The aim of this study was to develop and psychometrically test a short, patient-reported questionnaire to be used in clinical practice for patients with Irritable Bowel Syndrome (IBS). The Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS) questionnaire was designed to measure the treatment response of symptoms and well-being in patients suffering from IBS. METHODS The VAS-IBS was psychometrically tested for content and criterion validity, scale acceptability, item-reduction, internal reliability consistency, simplicity, and speed. Two samples were used. One expert panel (five physicians and four registered nurses), who gave their opinion on the content validity, and one of 71 patients with IBS (mean age 38 years SD +13, range 19-65), who completed the VAS-IBS, as well as the Gastrointestinal Symptom Rating Scale and the Psychological General Well-Being Index for criterion validity. RESULTS The items in the VAS-IBS capture the main physical concerns women with IBS might present and the psychometric testing confirmed that the VAS-IBS is an acceptable homogeneous patient-reported questionnaire indicated by Cronbach's alpha internal consistency reliability coefficient, with a value of 0.85. All correlations to test the criterion validity performed by using Pearson's correlation test, were statistically significant (p < 0.0001) and in the expected directions. The VAS-IBS is easy to complete and unproblematic to calculate. CONCLUSION The VAS-IBS appears to be reliable and user-friendly, for patients as well as for health professionals. The final version of the VAS-IBS including nine items needs to be further tested in clinical practice cross-culturally in women as well as in men.