Evaluation of a questionnaire in the assessment of patients with faecal incontinence and constipation.

Abstract

A self-reported questionnaire may be a useful instrument in assessing patients with faecal incontinence and constipation. Reliability, discrimination, validity, and sensitivity were evaluated in 16 control subjects 36 patients with faecal incontinence, and in 38 with constipation. The reliability was measured by a test-retest procedure (kappa (kappa) statistics or Spearman rank test), and validity by comparing the questionnaire and a diary. Discrimination was assessed by comparing the patient groups with the controls, and sensitivity by comparing selected answers before and after treatment. Overall reliability (faecal incontinence group, mean kappa = 0.57; constipation group, mean kappa = 0.60; controls, mean kappa = 0.95) and validity were judged acceptable. In the incontinence group occurrence of faecal incontinence per se was reproducible (kappa = 0.66), as was the need to wear a pad (kappa = 0.85). Stool frequency, percentage toilet time spent straining and digitation was reproducible in patients with constipation (kappa = 0.80, r = 0.56; p < 0.001, kappa = 0.83 respectively). Several items distinguished both patient groups from healthy controls (p < 0.05 to p < 0.001). Sensitivity to surgical treatment was seen in several items in both patient groups. The questionnaire appears to be a valid measure of symptoms in faecal incontinence and constipation with sufficient discriminatory capacity.