Myosteatosis predicts bariatric surgery response: A longitudinal study in patients with morbid obesity

Abstract Context Data on the preoperative factors for bariatric surgery response in patients with morbid obesity are limited, and there are no studies on the relationship between myosteatosis and surgery response. Object We investigated the preoperative factors determining bariatric surgery response and the impact of preoperative muscle fat infiltration on bariatric surgery response. Methods This retrospective longitudinal cohort study included 125 individuals (37 men, 88 women) with morbid obesity who underwent bariatric surgery. Muscle fat infiltration [skeletal muscle fat index (SMFI)] was evaluated using computed tomography-based psoas muscle mass and density at the fourth lumbar level. A bariatric surgery response was defined as ≥50% excessive weight loss at 1 year postoperatively. Results Before bariatric surgery, the patient’s mean body weight and body mass index (BMI) were 107.0 kg and 39.0 kg/m2, respectively. After 1 year, the mean body weight was 79.6 kg. The mean excessive weight loss at 1 year was 75.6%, and 102 (81.6%) patients were categorized as responders. There were no statistically significant differences in initial BMI, age, sex, or proportion of diabetes between responders and nonresponders. Responders were more likely to have lower SMFI and triglyceride and glycated hemoglobin A1c levels than nonresponders at baseline (P < .05). Multiple logistic regression analysis showed that a lower baseline SMFI was associated with bariatric surgery response (odds ratio = 0.31, 95% confidence interval = 0.14-0.69, P = .004). Conclusion Preoperative myosteatosis may determine the response to bariatric surgery.