`"FIB-4" = ( A * AST )/( PC *sqrt( ALT ))`

Enter a value for all fields

The FIB-4 Score calculator computes the Fibrosis-4 score to measure the amount of scarring in a liver based on the patient's age, AST and ALT levels, and platelet count.

INSTRUCTIONS: Enter the following:

• (A) Age of Patient
• (AST) Aspartate Transaminase Level
• (PC) Platelet Count (billions per liter)
• (ALT) Alanine Transaminase Level

Fibrosis-4 Score (FIB-4): The calculator returns the score as a real number.

The Math / Science

The formula for FIB-4 is:

`"FIB-4" = (A * AST)/(PC * sqrt(ALT))`

where:

• FIB-4 = Fibrosis-4 Score
• A = Age of Patient in Years
• AST = Aspartate Transaminase enzyme level in units per liter
• PC = Platelet Count (billions per liter)
• ALT = Alanine Transaminase enzyme level in units per liter

Using This Score

Using a lower cutoff value of 1.45, a FIB-4 score <1.45 had a negative predictive value of 90% for advanced fibrosis (Ishak fibrosis score 4-6 which includes early bridging fibrosis to cirrhosis). In contrast, a FIB-4 >3.25 would have a 97% specificity and a positive predictive value of 65% for advanced fibrosis. In the patient cohort in which this formula was first validated, at least 70% patients had values <1.45 or >3.25. Authors argued that these individuals could potentially have avoided liver biopsy with an overall accuracy of 86%.

Sources

Sterling RK, Lissen E, Clumeck N, et. al. Development of a simple noninvasive index to predict significant fibrosis patients with HIV/HCV co-infection. Hepatology 2006;43:1317-1325.