Impact of metabolic and bariatric surgery on MASLD: histological resolution and metabolic outcomes in a retrospective cohort

BACKGROUND: Metabolic dysfunction-associated steatotic liver disease (MASLD) involves a spectrum of liver histopathological changes. Obesity is recognized as a risk factor for MASLD. Metabolic and bariatric surgery (MBS) has emerged as a promising therapeutic option. OBJECTIVES: To evaluate the impact of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) on liver histology, function, and metabolic parameters in patients with obesity and MASLD. METHODS: This retrospective cohort study included patients who met diagnostic criteria of MASLD and underwent MBS between 2013 and 2023. Paired liver biopsies were obtained during the initial surgery and subsequent operations. The primary outcome was histological improvement, assessed by the NAFLD Activity Score (NAS). Secondary outcomes included changes in body weight, liver enzymes, and metabolic parameters. RESULTS: Of 13 obese patients with histologically confirmed MASLD, the median baseline BMI was 45 [42-50] kg/m², the mean age at the time of surgery was 42 ± 11 years, and 62% were female. Over a mean follow-up of 38 months, patients experienced significant weight loss, with an average total weight loss of 30%. Liver enzymes and metabolic parameters showed marked improvements, including significant reductions in AST, ALT, HbA1c, LDL, and triglyceride levels. Histological analysis revealed that 10 patients (77%) achieved complete resolution of steatohepatitis (NAS = 0), 2 (15%) showed partial improvement, and 1 (8%) remained unchanged. All patients with baseline hepatic fibrosis (54%) demonstrated complete fibrosis resolution. On multivariate analysis, no predictors were significantly associated with postoperative NAS. CONCLUSION: MBS is significantly associated with liver histology and metabolic markers improvement in obese patients with MASLD. High improvement rates support its role as an effective treatment modality.