Foregut bypass vs. restrictive bariatric procedures for nonalcoholic fatty liver disease: a meta-analysis of 3,355 individuals

BACKGROUND: Bariatric surgery represents an important treatment option for severely obese patients with nonalcoholic fatty liver disease (NAFLD). However, there remains inadequate data regarding the effects of different bariatric procedures on various NAFLD parameters, especially for histological outcomes. Thus, this meta-analysis aimed to compare the effects of restrictive bariatric procedures and foregut bypass on the metabolic, biochemical, and histological parameters for patients with NAFLD. METHODS: Medline and Embase were searched for articles relating to bariatric procedures and NAFLD. Pairwise meta-analysis was conducted to compare efficacy of bariatric procedures pre- vs. post-procedure with subgroup analysis to further compare restrictive against foregut bypass procedures. RESULTS: Thirty-one articles involving 3,355 patients who underwent restrictive bariatric procedures (n=1,460) and foregut bypass (n=1,895) were included. Both foregut bypass (P<0.01) and restrictive procedures (P=0.03) significantly increased odds of fibrosis resolution. Compared to restrictive procedures, foregut bypass resulted in a borderline non-significant decrease in fibrosis score (P=0.06) and significantly lower steatosis score (P<0.001). For metabolic parameters, foregut bypass significantly lowered body mass index (P=0.003) and low-density lipoprotein (P=0.008) compared to restrictive procedures. No significant differences were observed between both procedures for aspartate aminotransferase (P=0.17) and alkaline phosphatase (P=0.61). However, foregut bypass resulted in significantly lower gamma-glutamyl transferase than restrictive procedures (P=0.01) while restrictive procedures resulted in significantly lower alanine transaminase than foregut bypass (P=0.02). CONCLUSIONS: The significant histological and metabolic advantages and comparable improvements in biochemical outcomes support the choice of foregut bypass over restrictive bariatric procedures in NAFLD management.