Liver Fibrosis Tests and Outcomes of Bariatric Surgery in Morbidly Obese Patients With MASLD

ABSTRACT Aims Metabolic dysfunction‐associated steatotic liver disease (MASLD) is common among morbidly obese patients, but data on non‐invasive tests (NITs)' accuracy for liver fibrosis assessment are limited. We aimed to validate NITs for predicting liver fibrosis and post‐bariatric surgery outcomes. Methods This single‐tertiary‐center retrospective cross‐sectional study with longitudinal follow‐up included morbidly obese adults with biopsy‐proven MASLD undergoing bariatric surgery (laparoscopic Roux‐en‐Y gastric bypass [LRYGB] or laparoscopic sleeve gastrectomy [LSG]) between January 2011 and December 2022. Follow‐up exceeded 1 year. The primary outcome was NITs' performance in predicting liver fibrosis, including liver stiffness measurement (LSM), fibrosis‐4 (FIB‐4), non‐alcoholic fatty liver disease (NAFLD) fibrosis score (NFS), aspartate aminotransferase (AST) to platelet ratio index (APRI), and body mass index (BMI), AST/alanine aminotransferase (ALT) ratio and diabetes (BARD) scores. Secondary outcomes included biochemical and anthropometric changes. Data were compared using χ 2 test, t ‐test, or Wilcoxon tests as appropriate. The predictive performance of NITs was evaluated using receiver‐operating characteristics curve, and changes during follow‐up were assessed with paired tests. Results Among 193 patients (103 [53.4%] female, mean age 36.3 ± 10.9 years, mean BMI 47.70 ± 14.40 kg/m 2 , 78 [40.4%] with diabetes), 58 (30.1%) had liver fibrosis (≥ F1), and 10 (5.2%) had significant fibrosis (≥ F2). NITs showed low diagnostic accuracy for liver fibrosis (area under the receiver‐operating characteristics curve [AUROC]s: LSM 0.38, FIB‐4 0.59, NFS 0.53, APRI 0.50, BARD 0.51). After a median follow‐up of 1.9 years, LSM significantly decreased post‐surgery (7.80 to 5.50 kPa, p < 0.001). APRI and NFS improved (0.21 to 0.18, –0.773 to –1.395, p < 0.001), while FIB‐4 and BARD scores increased (0.52 to 0.60, 2 to 3, p < 0.001) over a median follow‐up of 2.9 years. Anthropometrically, over a median postoperative follow‐up of 2.9 years, BMI decreased significantly (47.70 to 35.05 kg/m 2 , p < 0.001). LRYGB had a higher percentage of total weight loss (%TWL) than LSG (30.8% vs. 28.5%, p = 0.040). Biochemical parameters (AST, ALT, platelets, glycated hemoglobin [HbA1C], low density lipoprotein [LDL]‐cholesterol, and triglycerides) improved significantly post‐surgery (all p < 0.001). Subgroup analysis ( n = 27) showed LSM improvement of > 20% correlated with %TWL > 30% ( p = 0.041). Conclusion Bariatric surgery improved long‐term clinical/biological outcomes, although NITs demonstrated poor diagnostic accuracy for baseline liver fibrosis. Research is needed to assess new NITs for monitoring liver fibrosis in morbidly obese patients.