Validation of a specific quality of life questionnaire for functional digestive disorders

Background-Dyspepsia and irritable bowel syndrome are suitable conditions f or assessment of quality of life. Their similarities justify the elaboratio n of a single specific questionnaire for the two conditions. Aims-To examine the process leading to the validation of the psychometric p roperties of the functional digestive disorders quality of life questionnai re (FDDQL). Methods-Initially, the questionnaire was given to 154 patients, to assess i ts acceptability and reproducibility, analyse its content, and reduce the n umber of items. Its responsiveness was tested during two therapeutic trials which included 428 patients. The questionnaire has been translated into Fr ench, 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 irritable bowel syndrome, defined by the Rome c riteria, filled in the FDDQL and generic SF-36 questionnaires. Results-The structure of the FDDQL scales was checked by factorial analysis . Its reliability was expressed by a Cronbach's alpha coefficient of 0.94. Assessment of its discriminant validity showed that the more severe the fun ctional digestive disorders, the more impaired the quality of life (p<0.05) . Concurrent validity was supported by the correlation found between the FD DQL and SF-36 questionnaire scales. The final version of the questionnaire contains 43 items belonging to eight domains. Conclusions-The properties of the FDDQL questionnaire, available in French, English, and German, make it appropriate for use in clinical trials design ed to evaluate its responsiveness to treatment among patients with dyspepsi a and irritable bowel syndrome.