Digestive symptoms and their psychosocial impact: validation of a questionnaire

OBJECTIVE: Questionnaires evaluating digestive symptoms and their psychosocial impact have not been extensively validated in Norwegian populations. In this study a self-administered questionnaire developed in Norway is evaluated for this purpose. MATERIAL AND METHODS: The questionnaire, the Digestive Symptoms and Impact Questionnaire, DSIQ, was developed by a cooperative group of general practitioners and gastroenterologists. The DSIQ contains 18 similarly structured global-type questions focusing on the patient's own judgement. The validation was based on 567 patients with dyspeptic symptoms or reflux symptoms referred to gastroscopy from general practice. RESULTS: Eighty percent of the patients responded to all the questions. All response categories were used for all questions. Factor analysis revealed 4 subscales: abdominal pain and bowel symptoms; gastric dysfunction; health impairment and impairment of everyday life. A question about reflux symptoms was retained as a subscale on its own. Overall score was established by calculating the mean of all question responses. Test-retest reliability in stable patients (intraclass correlation coefficient, range 0.80- 0.91) and internal consistency reliability (Cronbach's alpha, range 0.65-0.91) were satisfactory. Criterion validity was supported by significant correlations to patients' globally estimated quality of life and the General Health Questionnaire (GHQ-30). Responsiveness in spontaneously improved patients or patients given effective treatment ranged from moderate to highly responsive (responsiveness statistic range from 0.54 to 2.83). CONCLUSIONS: The DSIQ is a self-administered, simple and well-validated method for evaluating digestive symptoms and their psychosocial impact. The DSIQ shows satisfactory internal consistency reliability, test-retest reliability, responsiveness and criterion validity.