Development of a clinical trials version of the Impact of Weight on Quality of Life-Lite questionnaire (IWQOL-Lite Clinical Trials Version): results from two qualitative studies

Existing measures of health-related quality of life and patient functioning in obesity, such as the Impact of Weight on Quality of Life-Lite (IWQOL-Lite) questionnaire, lack the developmental rigour required by the Food and Drug Administration (FDA) to support product labelling. Two iterative qualitative studies informed development of a version of the IWQOL-Lite questionnaire optimized for use in obesity clinical trials: the IWQOL-Lite Clinical Trials Version. Study 1 included 42 patients with body mass index (BMI) >= 30 kg m(-2) (obesity); and Study 2 included 29 patients with type 2 diabetes and BMI >= 27 kg m(-2) (overweight). Candidate items were selected and/or modified from the IWQOL-Lite or developed de novo based on concept elicitation and cognitive debriefing interviews, as well as input from clinical experts and the FDA. Participants consistently reported that excess weight limited physical activity and comfort, energy/stamina and self-confidence/self-esteem. Impacts on emotional, social and sexual functioning, as well as productivity and overall health, were also reported. Each concept addressed in the 22-item pilot IWQOL-Lite Clinical Trials Version was consistently reported as salient and likely to change with 10% weight loss. Data from ongoing and planned clinical trials will be used to finalize and conduct psychometric evaluations of the pilot measure in several patient populations.