Is the RAND-36 an Adequate Patient-reported Outcome Measure to Assess Health-related Quality of Life in Patients Undergoing Bariatric Surgery?

Purpose The RAND-36 is the most frequently used patient-reported outcome measure (PROM) to evaluate health-related quality of life (HRQoL) in bariatric surgery. However, the RAND-36 has never been adequately validated in bariatric surgery. The purpose of this study was to validate the RAND-36 in Dutch patients undergoing bariatric surgery. Material and Methods To validate the RAND-36, the following measurement properties were assessed in bariatric surgery patients: validity (the degree to which the RAND-36 measures what it purports to measure (HRQoL)), reliability (the extent to which the scores of the RAND-36 are the same for repeated measurement for patients who have not changed in HRQoL), responsiveness (the ability of the RAND-36 to detect changes in HRQoL over time). Results Two thousand one hundred thirty-seven patients were included. Validity was not adequate due to the irrelevance of some items and response options, the lack of items relevant to patients undergoing bariatric surgery, and the RAND-36 did not actually measure what it was intended to measure in this study (HRQoL in bariatric surgery patients). Reliability was insufficient for the majority of the scales (the scores of patients who had not changed in HRQoL were different when the RAND was completed a second time (intraclass correlation coefficient (ICC) values 0.10–0.69)). Responsiveness was insufficient. Conclusion The RAND-36 was not supported by sufficient validation evidence in patients undergoing bariatric surgery, which means that the RAND-36 does not adequately measure HRQoL in this patient population. Future research studies should use PROMs that are specifically designed for assessing HRQoL in patients undergoing bariatric surgery. Graphical abstract