Validation of a self administered questionnaire to elicit gastrointestinal symptoms.

Self administered questionnaires are becoming popular investigative tools in medical research, yet few reports state the extent of methods used to validate these questionnaires before their general use. A pilot study was therefore carried out to validate a 41 item questionnaire for use in a population screening study for gastrointestinal disease. Participants in the study comprised 69 population controls, 40 patients with benign disease, and 35 patients with gastrointestinal cancer. Acceptability, ease of completion, reliability, and reproducibility of the questionnaire were all assessed. Only one subject refused to complete the questionnaire. Ninety six per cent of the questions were completed by each subject and only one response in 1440 was altered in the reproducibility study. The questionnaire disclosed symptoms similar to those elicited by a clinician and highlighted unreported gastrointestinal symptoms in the control group. Three questions were found to be unreliable and were altered before the questionnaire was put into general use. It is concluded that a pilot study to validate a new questionnaire is simple to perform and necessary to identify unreliable questions.