Minimal important difference in weight loss following bariatric surgery: Enhancing BODY-Q interpretability.

BODY-Q is a patient-reported outcome measure for comprehensive assessment of outcomes specific to patients undergoing bariatric surgery. The clinical utility of BODY-Q is hampered by the lack of guidance on score interpretation. This study aimed to determine minimal important difference (MID) for assessment of BODY-Q. Prospective BODY-Q data from Denmark and the Netherlands pre- and post-bariatric surgery were collected. Two distribution-based methods were used to estimate MID by 0.2 standard deviations of baseline scores and the mean standardized response change of scores from baseline to 3-years postoperatively. In total, 5476 assessments from 2253 participants were included of which 1628 (72.3%) underwent Roux-en-Y gastric bypass, 586 (26.0%) sleeve gastrectomy, 33 (1.5%) gastric banding, and 6 (0.03%) other surgeries. The mean age was 45.1 ± 10.9 with a mean BMI of 46.6 ± 9.6. Baseline MID ranged from 1 to 4 in health-related quality of life (HRQL) and from 2 to 8 in appearance scales. The mean change of scores ranged from 4 to 5 in HRQL and from 4 to 7 in the appearance scales. The estimated MID for the change in BODY-Q HRQL and appearance scales ranged from 3 to 8 and is recommended for use to interpret BODY-Q scores and assess treatment effects in bariatric surgery.