Validated questionnaire on diagnosis and symptom severity for functional constipation in the Chinese population

Functional constipation is a common problem in clinical practice. No validated questionnaire is available in Chinese.

To develop a validated questionnaire for diagnosis and symptom assessment in functional constipation for the Chinese population.

One hundred and eleven patients with constipation and 110 healthy controls were presented with a 24-item constipation questionnaire in the Chinese language. Quality of life in constipation patients was assessed by Short Form-36. Polyethylene glycol was prescribed, for 4 weeks, to 20 patients with newly diagnosed constipation. The questionnaire was administered before and 4 weeks after treatment. Concept, content, construct, discriminant validity and reliability of the questionnaire were assessed.

Six items were selected by logistic regression to account for most of the differences between controls and constipated patients with a good reproducibility and internal consistency. A cut-off score of > or =5 was determined to discriminate between controls and constipated patients with a sensitivity of 91% and a specificity of 91%. The constipation questionnaire correlated negatively with seven domains of the Short Form-36 and discriminated between constipated patients who reported symptomatic improvement during polyethylene glycol treatment.

The Chinese constipation questionnaire could be used in epidemiological studies to assess the frequency and severity of constipation in patient populations and in interventional studies of constipation.