Fibrosis-4 (FIB-4) | Healthmatters.io (2024)

Fibrosis-4 (FIB-4) is a clinical marker used to evaluate the degree of liver fibrosis, particularly in patients with chronic liver diseases like hepatitis C and non-alcoholic fatty liver disease (NAFLD). It is a non-invasive test that helps doctors assess the extent of liver damage without the need for a liver biopsy, which is more invasive and can be risky.

The FIB-4 index is calculated using a simple formula that includes the patient's age, levels of two liver enzymes (AST and ALT), and platelet count.

Specifically, the formula is:

FIB-4 Score = (Age* x AST) / (Platelets x √(ALT))

*Use with caution in patients <35or >65years old, as the score has been shown to be less reliable in these patients.

A higher FIB-4 score indicates a greater likelihood of significant liver fibrosis, while a lower score suggests minimal or no fibrosis. This test is particularly useful because it is derived from routine blood tests, making it accessible and cost-effective for monitoring liver health. Clinicians use the FIB-4 score to make decisions about the need for further testing, like imaging studies or liver biopsy, and to guide treatment plans for liver disease. Overall, the FIB-4 index is a valuable tool in the management of liver disease, helping to identify patients at risk for advanced liver fibrosis who might benefit from more aggressive treatment and monitoring.

When to useFibrosis-4 (FIB-4):

- 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.

Other notes:

- 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)

Why use Fibrosis-4 (FIB-4):

- 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 theNAFLD Fibrosis Score(Shah 2009).

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