Accuracy of Transient Elastography in assessing fibrosis at diagnosis in naïve patients with Primary Biliary Cholangitis: a dual cut-off approach

BACKGROUND & AIMS: Liver fibrosis holds a relevant prognostic meaning in primary biliary cholangitis (PBC). Non-invasive fibrosis evaluation using vibration-controlled transient elastography (VCTE) is routinely performed. However, there is limited evidence on its accuracy at diagnosis in PBC. We aimed to estimate the diagnostic accuracy of VCTE in assessing advanced fibrosis at disease presentation in PBC.APPROACH & RESULTS: We collected data from 167 consecutive treatment-naive PBC patients who underwent liver biopsy(LB) at diagnosis at six Italian centers. VCTE examinations were completed within 12 weeks of LB. Biopsies were scored by two blinded expert pathologists, according to Ludwig system. Diagnostic accuracy was estimated using the area under the receiver operating characteristic curves(AUROCs) for advanced fibrosis (Ludwig stage≥III). The effects of biochemical and clinical parameters on liver stiffness measurement (LSM) were appraised. Derivation cohort consisted of 126 patients with valid LSM and LB, VCTE identified patients with advanced fibrosis with AUROC of 0.89. LSM cut-offs ≤6.5kPa and >11.0kPa enabled to exclude and confirm, respectively, advanced fibrosis (negative predictive value[NPV]=0.94, positive predictive value[PPV]=0.89, error rate=5.6%). These values were externally validated in an independent cohort of 91 PBC patients(NPV=0.93, PPV=0.89, error rate=8.6%). Multivariable analysis found the only parameter affecting LSM was fibrosis stage. No association was found with BMI and liver biochemistry.CONCLUSIONS: In a multicenter study of treatment-naive PBC patients, we identified two cut-offs (LSM≤6.5kPa and>11.0kPa) able to discriminate at diagnosis the presence or the absence, respectively, of advanced fibrosis in PBC patients, with external validation. In patients with LSM between these two cut-offs, VCTE is not reliable and liver biopsy should be evaluated for accurate disease staging. BMI and liver biochemistry did not affect LSMs.