Digestive symptoms and their psychosocial impact: validation of a questionnaire

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.

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.

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).

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.