Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





    Chief Complaint


    Organ System


    Patent Pending

    Fibrosis-4 (FIB-4) Index for Liver Fibrosis

    Noninvasive estimate of liver scarring in HCV and HBV patients, to assess need for biopsy.
    When to Use
    Why Use
    • Patients with any known risk factors for liver disease, including chronic hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease (NAFLD) and the cholestatic and metabolic liver diseases.
    • Patients with known liver fibrosis should have their fibrosis trended over time to evaluate for progression or stabilization.
    • Liver fibrosis often progresses non-linearly, so it is important to be able to re-assess fibrosis trends in individual patients over time, and invasive re-assessments carry significant risk to patients. FIB-4 allows for non-invasive liver fibrosis assessment.
    • FIB-4 was developed in patients with HIV and HCV co-infection.
    • FIB-4 was developed to correlate with Ishak levels of fibrosis (by biopsy) with 3 levels:
      • 0-2 (mild fibrosis)
      • 3-4 (moderate fibrosis)
      • 5-6 (severe fibrosis/cirrhosis)
    • While liver biopsy is the gold standard for the diagnosis of liver fibrosis, it is not ideal; biopsy only evaluates a minute portion of the liver itself, so sampling errors can occur. Liver biopsy also comes with substantial morbidity.
    • Liver fibrosis often progresses non-linearly, so it is important to be able to re-assess fibrosis trends in individual patients over time.
    • It is critical that tests to identify liver cirrhosis are highly sensitive, as patients with the disease require screening for hepatocellular carcinoma (HCC) and gastroesophageal varices.
    • The FIB-4 Index was shown to be superior to 7 other noninvasive markers of fibrosis in patients with NAFLD, including the NAFLD Fibrosis Score (Shah 2009).


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    Next Steps
    Creator Insights


    • Low fibrosis scores may be appropriate candidates for medical management and may not require liver biopsy if FIB-4 scores continue to stay low.
    • Severe fibrosis/cirrhosis scores may need liver biopsy for confirmation of cirrhosis unless there are other clinical or imaging signs of progression to end-stage liver disease.


    Fibrosis 4 Score = (Age*AST) / (Platelets*√(ALT))

    Facts & Figures

    • FIB-4 scores <1.45 have a negative predictive value of 90% for advanced fibrosis (meaning minimal amounts of scarring) with 81% sensitivity.
    • FIB-4 scores >3.25 have a positive predictive value of 65% for advanced fibrosis with 97% specificity.
    • The original authors estimate that liver biopsy could have been avoided by using the FIB-4 Score with 86% accuracy.
    Dr. Richard Sterling

    About the Creator

    Richard K. Sterling, MD, is a professor and the chief of hepatology at Virginia Commonwealth University. His research interests include liver transplantation, HIV-HCV coinfection, acute and chronic liver disease, viral hepatitis C and B, and other hepatic pathologies.

    To view Dr. Richard Sterling's publications, visit PubMed