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

Abstract

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/m2.

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/m2.

Keywords: FibroScan-AST score (FAST score); Transient elastography; controlled attenuation parameter (CAP™); non-alcoholic fatty liver disease (NAFLD); obesity.

Conflict of interest statement

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/hbsn-20-787). Dr. MT reports personal fees from BMS, grants and personal fees from Falk Foundation, grants, personal fees and other from Gilead, grants, personal fees and other from Intercept, grants and personal fees from MSD, personal fees from Albireo, personal fees from Boehringer lngelheim, personal fees from BiomX, personal fees from Genfit, personal fees from Novartis, personal fees from Phenex, personal fees from Regulus, other from Abbvie, grants from Albireo, grants from Cymabay, grants from Takeda, outside the submitted work. In addition, Dr. MT has a patent Medical use of nor-UDCA (W02006119803 and W020099013334) licensed to Medical University of Graz. Dr. KS serves as an unpaid editorial board member of Hepatobiliary Surgery and Nutrition. The other authors have no conflicts of interest to declare.

2021 Hepatobiliary Surgery and Nutrition. All rights reserved.

Figures

Figure 1

Flow chart of study population. Patients with VCTE examinations >6 months prior to surgery, as well as

Figure 2

Diagnostic accuracy of VCTE, CAP™ and FAST according to per protocol and intent to diagnose-analysis. Diagnostic accuracy was calculated of VCTE for ≥F2, ≥F3 and NASH according to SAF, was calculated of CAP™ for ≥S2, S3 and NASH according to SAF and further calculated of FAST for ≥F2, ≥F3, ≥S2, S3, NASH according to SAF and active fibrotic NASH according to per protocol and intent to diagnose – analysis. Patients were stratified according to ≥/2 (VCTE, CAP™ and FAST) and steatosis <S3 (VCTE). In patients with <S3 and below the median BMI of 44.4 kg/m2 the accuracy of VCTE improved. VCTE, vibration controlled transient elastography; CAP™, Controlled Attenuation Parameter; AUC, area under the receiver operating characteristic, Sens, sensitivity, Spec, specificity; ≥F2, significant fibrosis; ≥F3, advanced fibrosis; ≥S2, significant steatosis; S3, severe steatosis; kPA, kilopascal; PP, per protocol; ITD, intent-to-diagnose; BMI, body mass index; NASH, non-alcoholic steatohepatitis; active fibrotic NASH, definition according to Newsome et al. (NASH + NAS ≥4 + F ≥2).

Figure 3

Per protocol liver stiffness measurement (LSM) and CAP™ distribution stratified for fibrosis, steatosis, and NASH according to histology. All groups were statistically compared, and significant differences marked by asterisks *, P