Background-Dyspepsia and irritable bowel syndrome are suitable conditions for assessment of quality of life. Their similarities justify the elaboration of a single specific questionnaire for the two conditions. Aims-To examine the process leading to the validation of the psychometric properties of the functional digestive disorders quality of life questionnaire (FDDQL). Methods-Initially, the questionnaire was given to 154 patients, to assess its acceptability and reproducibility, analyse its content, and reduce the number of items. Its responsiveness was tested during two therapeutic trials which included 428 patients. The questionnaire has been translated into French, English, and German. The psychometric validation study was conducted in France, United Kingdom, and Germany by 187 practitioners. A total of 401 patients with dyspepsia or irri- (Gut 1999;44:527-533) Keywords: digestive disorders; irritable bowel syndrome; dyspepsia; quality of life; clinical trial; validationThe need to assess subjective aspects of health related quality of life (QoL) under chronic conditions is now increasingly recognised. The prevalent functional digestive disorders (FDD), including functional dyspepsia (FD) and irritable bowel syndrome (IBS), constitute suitable conditions for the use of a quality of life questionnaire. For FDD, there is no specific function impairment and therefore no yardstick for therapeutic evaluation.1 2 Current criteria such as pain score correlate poorly with the patient's own evaluation of health status.3-5 FDD are chronic non-life threatening conditions, but have been reported to have a strong impact on daily activities, wellbeing, social performance, and psychological status, 6 7 even during symptom-free periods, because of the fear of the next bout of abdominal pain, the restrictions on social life and leisure, and the obligation to take drugs.
8QoL assessment explores the repercussions of the disease and the treatments as perceived by the patient.3 Like any other outcome criterion, a QoL questionnaire has to include psychometric data such as reliability, and content and construct validity. 4 5 9 When planning a clinical trial involving quality of life, the major concern is to select the most relevant, valid, and responsive questionnaire, which should be available in several languages. Generic instruments are designed to compare health status among diVerent populations, whatever the underlying condition.10 Their main drawback is their failure to stimulate responsiveness, as they do not focus specifically on the impact of a particular disease. They have rarely disclosed small but significant health status changes over time or during therapeutic trials. A disease specific questionnaire seems more pertinent to discrimination of the eVect of a particular therapy on the QoL. 10 An analysis of the literature did not show the existence of any specific questionnaire devoted to FDD when we started to elaborate our questionnaire. Our objectives were to draft and validate a specific questionnaire,...