The EQ-5D-5L is a valid approach to measure health related quality of life in patients undergoing bariatric surgery

Bariatric surgery is considered an effective treatment for individuals with severe and complex obesity. Besides reducing weight and improving obesity related comorbidities such as diabetes, bariatric surgery could improve patients' health-related quality of life. However, the frequently used instrument to measure quality of life, the EQ-5D has not been validated for use in bariatric surgery, which is a major limitation to its use in this clinical context. Our study undertook a psychometric validation of the 5 level EQ-5D (EQ-5D-5L) using clinical trial data to measure health-related quality of life in patients with severe and complex obesity undergoing bariatric surgery. Health-related quality of life was assessed at baseline (before randomisation) and six months later in 189 patients in a randomised controlled trial of bariatric surgery. Patients completed two generic health-related quality of life instruments, the EQ-5D-5L and SF-12, which were used together for the validation using data from all patients in the trial as the trial is ongoing. Psychometric analyses included construct and criterion validity and responsiveness to change. Of the 189 validation patients, 141 (75%) were female, the median age was 49 years old (range 23-70 years) and body mass index ranged from 33-70 kg/m2. For construct validity, there were significant improvements in the distribution of responses in all EQ-5D dimensions between baseline and 6 months after randomisation. For criterion validity, the highest degree of correlation was between the EQ-5D pain/discomfort and SF-12 bodily pain domain. For responsiveness the EQ-5D and SF-12 showed statistically significant improvements in health-related quality of life between baseline and 6 months after randomisation. The EQ-5D-5L is a valid generic measure for measuring health-related quality of life in bariatric surgery patients.