Baseline Presence of NAFLD Predicts Weight Loss after Gastric Bypass Surgery for Morbid Obesity.

Background: Bariatric surgery is a widely used treatment for morbid obesity. Prediction of postoperative weight loss currently relies on prediction models, which mostly overestimate patients' weight loss. Data about the influence of nonalcoholic fatty liver disease (NAFLD) on early postoperative weight loss are scarce. Methods: This prospective, single-center cohort study included 143 patients receiving laparoscopic gastric bypass surgery (one anastomosis-mini gastric bypass [OAGB-MGB] or Roux-en-Y gastric bypass [RYGB]). Liver biopsies were acquired at surgery. NAFLD activity score (NAS) assigned patients to "No NAFLD," "NAFL," or "NASH." Follow-up data were collected at 3, 6, and 12 months. Results: In total, 49.7 percent of patients had NASH, while 41.3 percent had NAFL. Compared to the No NAFLD group, NAFL and NASH showed higher body mass index (BMI) at follow-up (6 months: 31.0kg/m2 vs. 36.8kg/m2 and 36.1kg/m2, 12 months: 27.0kg/m2 vs. 34.4 and 32.8kg/m2) and lower percentage of total body weight loss (%TBWL): (6 months: 27.1% vs. 23.3% and 24.4%; 12 months: 38.5% vs. 30.1 and 32.6%). Linear regression of NAS points significantly predicts percentage of excessive weight loss (%EWL) after 6 months (Cologne-weight-loss-prediction-score). Conclusion: Histopathological presence of NAFLD might lead to inferior postoperative weight reduction after RYGB. The mechanisms underlying this observation should be further studied. [ABSTRACT FROM AUTHOR]