Gastric bypass specifically impairs liver parameters as compared with sleeve gastrectomy, independently of evolution of metabolic disorders.

Background: Numerous studies have shown that Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) differently affect metabolic disorders associated with obesity. While bariatric surgery has been shown to improve nonalcoholic fatty liver disease, very few studies have compared liver parameters after both procedures.

Objectives: To compare the evolution of liver parameters after SG and RYGB and their relationships with improvement of metabolic disorders.

Methods: Metabolic parameters and abdominal ultrasonography were recorded before and 1 year after bariatric surgery in all patients who underwent SG or RYGB between 2004 and 2016 in our institution.

Setting: University hospital, Colombes, France.

Results: Five hundred thirty-three patients (15% men, age 43 ± 11 yr) were analyzed, including 326 who underwent RYGB and 207 who underwent SG. Before surgery, body mass index (44.7 ± 5.7 versus 44.4 ± 7.4 kg/m²) and metabolic parameters were not significantly different. One year after surgery, RYGB induced greater weight loss (31.9 ± 7.7 versus 28.6 ± 8.3 %, P < .001). Metabolic parameters improved in both groups, but fasting insulin, low-density lipoprotein cholesterol, C-reactive protein, and ferritin were lower after RYGB (P < .001). In contrast, transaminases were higher after RYGB compared with SG (alanine aminotransferase: 31.6 ± 18.7 versus 22.6 ± 7.7 IU/L; P < .001). The persistence of alanine aminotransferase >34 IU/L (27% versus 7% of patients, P < .001) was independent of the persistence of steatosis on ultrasonography (39% versus 37% of patients) 1 year after RYGB and SG, respectively.

Conclusion: Despite a greater improvement of metabolic disorders, RYGB has less beneficial effect on liver parameters compared with SG. Further studies are required to define the mechanisms explaining these differences between both procedures.