Accuracy of non-invasive liver stiffness measurement and steatosis quantification in patients with severe and morbid obesity

Background:Vibration controlled transient elastography(VCTE)and controlled attenuation parameter(CAP™)have shown reliable performance predicting fibrosis and steatosis in normal-to overweight patients but have not been validated in severe to morbid obesity.This study aimed at determining the accuracy of VCTE,CAP™and the composite score FibroScan-AST(FAST)in patients with a body mass index(BMI)of≥35 kg/m^(2).Methods:Patients scheduled for bariatric-metabolic surgery underwent preoperative VCTE/CAP™measurement,and intraoperative liver biopsy.The feasibility and accuracy of VCTE,CAP™and the composite score FAST were retrospectively analysed to evaluate fibrosis,steatosis and active fibrotic non-alcoholic steatohepatitis[NASH+non-alcoholic fatty liver disease(NAFLD)activity score≥4+fibrosis grade≥2]using per protocol(PP)and intent to diagnose(ITD)calculation.Results:In total,170 patients(median BMI 44.4 kg/m²)were included in the study.Liver biopsy showed NASH,simple steatosis,and normal livers in 60.6%(n=103),28.8%(n=49),and 10.6%(n=18),respectively.VCTE and CAP™delivered reliable results in 90.6%(n=154/170)and 90.5%(n=134/148).The AUC(PP)of VCTE,CAP™,and FAST were 0.687(≥F2),0.786(≥F3),0.703(≥S2),0.738(S3),and 0.780(active fibrotic NASH).The AUC increased to 0.742(≥F2),0.842(≥F3),0.712(≥S2),0.780(S3),and 0.836(active fibrotic NASH)in patients below the median BMI of 44.4 kg/m².Conclusions:VCTE,CAP™and FAST show acceptable accuracy for the detection of fibrosis,steatosis and NASH in a real-life cohort of patients with obesity.Accuracy improves in patients with a BMI<44.4 kg/m^(2).