Background and aims

Patients with NAFLD with significant hepatic fibrosis (Stage ≥ 2) are at increased risk of liver-related morbidity and are candidates for pharmacologic therapies. In this study, we compared the diagnostic accuracy of MEFIB (the combination of magnetic resonance elastography [MRE] and Fibrosis-4 [FIB-4]) and FAST (FibroScan-aspartate aminotransferase; combined liver stiffness measurement by vibration-controlled transient elastography, controlled attenuation parameter, and aspartate aminotransferase) for detecting significant fibrosis.

Approach and results

This prospective cohort study included 234 consecutive patients with NAFLD who underwent liver biopsy, MRE, and FibroScan at the University of California San Diego (UCSD cohort) and an independent cohort (N = 314) from Yokohama City University, Japan. The primary outcome was diagnostic accuracy for significant fibrosis (Stage ≥ 2). The proportions of significant fibrosis in the UCSD and Yokohama cohorts were 29.5% and 66.2%, respectively. Area under the receiver operating characteristic curve (95% CI) of MEFIB (0.860 [0.81-0.91]) was significantly higher than that of FAST (0.757 [0.69-0.82]) in the UCSD cohort (p = 0.005), with consistent results in the Yokohama cohort (AUROC, 0.899 [MEFIB] versus 0.724 [FAST]; p < 0.001). When used as the rule-in criteria (MEFIB, MRE ≥ 3.3 kPa and FIB-4 ≥ 1.6; FAST ≥ 0.67), the positive predictive value for significant fibrosis was 91.2%-96.0% for MEFIB and 74.2%-89.2% for FAST. When used as the rule-out criteria (MEFIB, MRE < 3.3 kPa and FIB-4 < 1.6; FAST ≤ 0.35), the negative predictive value for significant fibrosis was 85.6%-92.8% for MEFIB and 57.8%-88.3% for FAST.

Conclusions

MEFIB has higher diagnostic accuracy than FAST for significant fibrosis in NAFLD, and our results support the utility of a two-step strategy for detecting significant fibrosis in NAFLD.

Background & aims

A two-step strategy combining a serum marker and magnetic resonance elastography (MRE) for detecting advanced fibrosis (stage 3-4) among patients with nonalcoholic fatty liver disease (NAFLD) has been proposed, but its diagnostic accuracy has not been evaluated. In this multicenter study, we aimed to investigate the diagnostic accuracy of a two-step strategy including Fibrosis-4 (FIB-4) followed by MRE.

Methods

In this multicenter study, 806 patients with biopsy-proven NAFLD who underwent contemporaneous MRE were enrolled and randomly assigned to training and validation cohorts. As a first step, patients with FIB-4 <1.3 were defined as test negative regardless of MRE. As a second step, among patients with FIB-4 ≥1.3, MRE <3.6 and ≥3.6 kPa were defined as test negative and positive. The primary outcome was the diagnostic accuracy for advanced fibrosis comparing MRE alone versus the two-step strategy.

Results

Area under the receiver characteristic curves of MRE alone and the two-step strategy were 0.840 and 0.853 in the training cohort (P = .4) and 0.867 and 0.834 in the validation cohort (P = .2), respectively, and the diagnostic accuracy was comparable between the 2 methods. In the entire cohort, negative predictive value (NPV) and positive predictive value (PPV) of MRE for advanced fibrosis were 92.2% and 73.7%, respectively, whereas NPV at the first and second step and PPV at the second step were 90.9%, 84.4%, and 77.0%, respectively.

Conclusions

The diagnostic accuracy of the two-step strategy was comparable to MRE and could reduce cost by reducing excessive MRE. Therefore, the two-step strategy could be used as a screening method in a large population.

Background

Clinical trials enroll patients with active fibrotic nonalcoholic steatohepatitis (NASH) (nonalcoholic fatty liver disease [NAFLD] activity score ≥ 4) and significant fibrosis (F ≥ 2); however, screening failure rates are high following biopsy. We developed new scores to identify active fibrotic NASH using FibroScan and magnetic resonance imaging (MRI).

Methods

We undertook prospective primary (n = 176), retrospective validation (n = 169), and University of California San Diego (UCSD; n = 234) studies of liver biopsy-proven NAFLD. Liver stiffness measurement (LSM) using FibroScan or magnetic resonance elastography (MRE), controlled attenuation parameter (CAP), or proton density fat fraction (PDFF), and aspartate aminotransferase (AST) were combined to develop a two-step strategy-FibroScan-based LSM followed by CAP with AST (F-CAST) and MRE-based LSM followed by PDFF with AST (M-PAST)-and compared with FibroScan-AST (FAST) and MRI-AST (MAST) for diagnosing active fibrotic NASH. Each model was categorized using rule-in and rule-out criteria.

Results

Areas under receiver operating characteristic curves (AUROCs) of F-CAST (0.826) and M-PAST (0.832) were significantly higher than those of FAST (0.744, p = 0.004) and MAST (0.710, p < 0.001). Following the rule-in criteria, positive predictive values of F-CAST (81.8%) and M-PAST (81.8%) were higher than those of FAST (73.5%) and MAST (70.0%). Following the rule-out criteria, negative predictive values of F-CAST (90.5%) and M-PAST (90.9%) were higher than those of FAST (84.0%) and MAST (73.9%). In the validation and UCSD cohorts, AUROCs did not differ significantly between F-CAST and FAST, but M-PAST had a higher diagnostic performance than MAST.

Conclusions

The two-step strategy, especially M-PAST, showed reliability of rule-in/-out for active fibrotic NASH, with better predictive performance compared with MAST. This study is registered with ClinicalTrials.gov (number, UMIN000012757).