An overview of obesity-specific quality of life questionnaires.

The measurement of quality of life in patients with obesity is useful to evaluate the effects of treatment (including bariatric surgery) and may influence the development of clinical pathways, service provision, healthcare expenditures and public health policy. Consequently, clinicians, researchers and policy makers must rely on valid measurement instruments. We reviewed 11 obesity-specific quality of life questionnaires and classified them according to their domain of interest and described their measurement properties (specifications, validity, reliability, responsiveness and interpretability). We found that (i) nine questionnaires were developed specifically to be used as evaluative instruments in clinical trials; (ii) only three targeted populations with morbid obesity (body mass index > 40 kg m(-2)); (iii) construct validity was properly studied in three questionnaires; (iv) demonstration of responsiveness from independent randomized controlled trials was available for two of the 11 questionnaires; (v) keys to interpretation of scores were provided for three questionnaires. Future research should include further validation and a better definition of the interpretability of existing instruments.