While patient-reported outcome measures are available to evaluate health-related quality of life and functioning in obesity, existing measures do not evaluate the impact of excess weight and weight loss on the ability to perform regularly occurring daily activities. Three iterative sets of qualitative interviews were conducted in two countries (United States, n = 23; United Kingdom, n = 23) with individuals with body mass index ≥30 kg/m2 to inform development of the Impact of Weight on Daily Activities Questionnaire (IWDAQ) for use in clinical trials to evaluate daily activity limitations associated with excess weight. Candidate concepts were selected based on the literature, expert opinion, and previously conducted qualitative research, after which the draft IWDAQ was developed and tested. Interviews included a brief concept elicitation phase, followed by cognitive debriefing during which the IWDAQ was refined based upon participants' feedback. The IWDAQ uses a novel, adaptive questionnaire design, such that clinical trial participants choose the three IWDAQ activities they would most like to improve with weight loss and rate the degree of limitation in each of these activities at baseline. By allowing individuals participating in trials to identify and monitor changes in the activities they most want to see improve with weight loss, the 19-item IWDAQ has the potential to detect the benefits of weight-loss treatment that individuals with obesity value most.
