Impact of Roux-en-Y Gastric Bypass on the Evolution of Fibrotic NASH: One-Year Follow-Up

Background: Non-alcoholic fatty liver disease (NAFLD) includes simple steatosis and non-alcoholic steatohepatitis (NASH), with fibrosis in NASH serving as a critical prognostic marker. Objective: This study investigates the effects of Roux-en-Y gastric bypass (RYGB) on fibrotic NASH, assessed using the Fibrotic NASH Index (FNI). Methods: A retrospective cohort study was conducted involving 104 individuals (91.3% female, mean age 39.4 ± 8.6 years) who underwent RYGB. Histopathological evaluations during surgery identified fibrotic NASH, and FNI scores were calculated at baseline and one year post-surgery. Results: At the time of surgery, participants had a mean BMI of 35.3 ± 2.8 kg/m², which decreased to 27.1 ± 4.0 kg/m² one year after surgery. The mean % total weight loss (%TWL) was 23.8 ± 10.1%, and the mean % excess weight loss (%EWL) was 82.4 ± 37.3%. Fibrotic NASH was present in 17.3% of participants pre-operatively. The mean FNI score decreased significantly from 0.16 to 0.07 (p<0.0001) after surgery. Factors associated with improvement in the FNI included female gender (p=0.0009), higher alanine aminotransferase (ALT) levels (p=0.02), presence of lobular inflammation (p=0.03), and pre-operative histological evidence of fibrotic NASH (p=0.04). The FNI demonstrated high diagnostic accuracy (sensitivity: 61.1%, specificity: 96.4%, overall accuracy: 90.2%). Conclusion: RYGB effectively promotes the resolution of fibrotic NASH, highlighting its potential as a therapeutic intervention to mitigate progression to cirrhosis and hepatocellular carcinoma. The FNI is a reliable, non-invasive tool for assessing fibrotic NASH, warranting further research on its long-term impact on liver health.