Fig. 1

Flow diagram of the development and validation of the Digestion-associated Quality of Life Questionnaire (DQLQ). The first draft of the questionnaire was developed after a review of literature and with input from an expert panel of gastrointestinal researchers. After testing and focus group input, it was revised to a nine-items questionnaire with a seven-point frequency Likert scale. Assessment of the reliability and validity of the DQLQ was then assessed as part of a large clinical trial