From the Guidelines
To calculate the FIB-4 (Fibrosis-4 index), use the formula: FIB-4 = (Age × AST) / (Platelets × √ALT). This requires four specific values: the patient's age in years, AST (aspartate aminotransferase) in U/L, ALT (alanine aminotransferase) in U/L, and platelet count in 10^9/L. For example, if a patient is 50 years old with AST of 40 U/L, ALT of 36 U/L, and platelets of 200 × 10^9/L, the calculation would be: (50 × 40) / (200 × √36) = 2000 / (200 × 6) = 2000 / 1200 = 1.67. The FIB-4 score helps assess liver fibrosis severity, particularly in patients with chronic liver diseases like hepatitis or fatty liver disease. A score below 1.3 suggests minimal fibrosis, while a score above 3.25 indicates advanced fibrosis, as supported by recent studies 1. This non-invasive test uses readily available laboratory values to help clinicians evaluate liver fibrosis without requiring a liver biopsy, though it should be interpreted alongside other clinical findings and tests for comprehensive liver assessment.
Some key points to consider when using the FIB-4 score include:
- A FIB-4 score <1.3 can reliably exclude advanced fibrosis in patients with NAFLD, with a negative predictive value of ≥90% 1.
- Patients with FIB-4 scores between 1.3 and 2.67 are at indeterminate risk and may benefit from further workup to confirm the stage of hepatic fibrosis 1.
- The FIB-4 score is a useful, inexpensive, first-line assessment of liver fibrosis for use in primary care, and can be used to identify patients who require referral to a hepatologist for further evaluation and management 1.
- The FIB-4 score should be interpreted in the context of other clinical findings and tests, including liver function tests, imaging studies, and liver biopsy, to provide a comprehensive assessment of liver fibrosis severity.
Overall, the FIB-4 score is a valuable tool for assessing liver fibrosis severity in patients with chronic liver diseases, and can help clinicians make informed decisions about patient management and referral to specialist care.
From the Research
Calculation of FIB-4
To calculate the FIB-4 index, the following formula is used:
- FIB-4 = (age × AST) / (platelet count × ALT^0.5) 2 This formula takes into account the patient's age, aspartate aminotransferase (AST) levels, platelet count, and alanine aminotransferase (ALT) levels.
Interpretation of FIB-4 Results
The FIB-4 index can be used to predict the severity of liver fibrosis, with higher scores indicating more severe fibrosis. The following cut-off values have been suggested:
- FIB-4 < 1.3: low risk of fibrosis
- FIB-4 1.3-2.67: intermediate risk of fibrosis
- FIB-4 > 2.67: high risk of fibrosis 3 It is essential to note that the FIB-4 index should be used in conjunction with other diagnostic tests, such as the ELF test, to confirm the presence and severity of liver fibrosis.
Clinical Applications of FIB-4
The FIB-4 index has been used in various clinical settings to assess liver fibrosis, including: