RESUMO
BACKGROUND: Bariatric surgery gains attention as a potential treatment for non-alcoholic fatty liver disease (NAFLD). The present study aimed to evaluate improvement of NAFLD after the two most common bariatric procedures with validated non-invasive instruments. MATERIAL AND METHODS: N = 100 patients scheduled for laparoscopic sleeve gastrectomy (LSG) or Roux-en-Y gastric bypass (RYGB) were included. NAFLD was evaluated preoperatively and postoperatively with liver stiffness measurement by transient elastography and laboratory-based fibrosis scores. Clinical data included body mass index (BMI), total weight loss (%TWL), excess weight loss (%EWL), age, gender, comorbidities, and the Edmonton obesity staging system (EOSS). RESULTS: There were significant improvements of BMI, %TWL, %EWL, and EOSS after bariatric surgery. Liver stiffness was significantly improved from pre- to postoperative (12.9 ± 10.4 vs. 7.1 ± 3.7 kPa, p < 0.001) at median follow-up of 12.5 months. Additionally, there were significant improvements of liver fibrosis scores (aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio 0.8 ± 0.3 vs. 1.1 ± 0.4, p < 0.001; NAFLD fibrosis score - 1.0 ± 1.8 vs. - 1.7 ± 1.3, p < 0.001; APRI score 0.3 ± 0.2 vs. 0.3 ± 0.1, p = 0.009; BARD score 2.3 ± 1.2 vs. 2.8 ± 1.1, p = 0.008) and laboratory parameters (ALT, AST, and GGT). After adjustment for baseline liver stiffness, RYGB showed higher improvements than LSG, and there was no gender difference. Improvement of liver stiffness was not correlated to improvement of BMI, %TWL, %EWL, or EOSS. CONCLUSIONS: NAFLD seems to be improved by bariatric surgery as measured by validated non-invasive instruments. Furthermore, it appears that RYGB is more effective than LSG. No correlation could be detected between NAFLD and weight loss. The present study highlights the potential of bariatric surgery for successful treatment of NAFLD. Further research is required to understand the exact mechanisms.