Identification and external validation of the optimal FIB-4 and APRI thresholds for ruling in chronic hepatitis B related liver fibrosis in tertiary care settings.

Background: With the initially defined thresholds, the most widely used serum biomarkers for staging liver fibrosis (ie, APRI and FIB-4 scores) proved to be ineffective among patients with chronic hepatitis B virus infection (CHB). Whether optimizing the FIB-4 and APRI thresholds could improve their diagnostic accuracy requires further research.

Methods: Using data of treat-naïve CHB patients from three tertiary hospitals, we explored the optimal FIB-4 and APRI thresholds to rule in liver fibrosis accurately. Subsequently, we validated the applicability of the newly defined thresholds to the CHB patients from another two tertiary hospitals.

Results: The fibrosis stages between discovery cohort (n = 433) and the external validation cohort (n = 568) were statistically different (P < .001). When ruling in significant fibrosis and advanced fibrosis by the newly defined FIB-4 thresholds (2.25 and 3.00, respectively), 24.0% and 14.3% of patients, respectively, could be classified with excellent accuracy (PPVs of 91.3% and 80.6%, respectively; misdiagnosis rates of 6.0% and 5.4%, respectively), supported by the internal and external validation tests. Regrettably, the more accurate and robust thresholds of APRI score for ruling in significant fibrosis and advanced fibrosis could not be found. Besides, the FIB-4 and APRI scores should not be recommended for ruling in cirrhosis because of poor clinical diagnostic performance.

Conclusion: The newly defined FIB-4 thresholds for ruling in significant fibrosis and advanced fibrosis showed superior and reproducible clinical diagnostic accuracy. The well-validated threshold (≥2.25) of FIB-4 score could aid in antiviral treatment decisions for treat-naïve adult CHB patients by accurately ruling in significant fibrosis in tertiary care settings.