NAFLD Fibrosis Score Calculator

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease worldwide. It is assumed that this disorder is present in approximately 25% of the world's population. NAFLD is associated with an excessive fat build-up in the liver without another clear cause, e.g. alcohol use. Usually it does not give noticeable signs and is often diagnosed during routine health checks. In some cases, NAFLD can cause symptoms related to liver dysfunction, which include fatigue, malaise, or mild yellow discoloration of the skin. NAFLD may eventually lead to complications such as cirrhosis, liver cancer, liver failure, or cardiovascular disease.

The risk factors of NAFLD include:

• Being overweight or obese;
• Diabetes;
• Metabolic syndrome;
• Diet rich in fructose; and
• Older age.

Liver biopsy is considered to be the gold standard for the diagnosis and assessment of liver fibrosis, however this method has several limitations, which include high cost and invasiveness. Therefore, a noninvasive indicator of liver fibrosis in patients with NAFLD has been developed - the NAFLD fibrosis score.

It consists of six following components:

• Age;
• Presence of hyperglycemia;
• BMI (body mass index);
• Platelet count;
• Albumin level; and
• Aspartate aminotransferase and alanine aminotransferase ratio - find out more in a dedicated (AST/ALT) ratio calculator.

The NAFLD fibrosis score was found to independently identify NAFLD patients with and without advanced fibrosis at the initial NAFLD diagnosis. Moreover, several studies validated it and confirmed that it has acceptable sensitivity, specificity, and positive and negative predictive values for advanced liver fibrosis.

NAFLD fibrosis score calculator uses the following formula to compute the NAFLD fibrosis score:

NFS = -1.675 + (0.037 × age) + (0.094 × BMI) + (1.13 × hyperglycemia) + (0.99 × AST/ALT ratio) - (0.013 × platelet count) - (0.66 × albumin)

where:

NFS - NAFLD fibrosis score;

age - age expressed in years;

BMI - Body Mass Index expressed in kg/m² (the NAFLD fibrosis score calculator calculates it for you);

hyperglycemia - presence of impaired fasting glucose or diabetes (yes = 1, no = 0);

AST/ALT ratio - AST and ALT levels expressed in IU/L (the NAFLD fibrosis score calculator calculates AST/ALT ratio for you);

platelet count - platelet count expressed in 10⁹/L; and

albumin - albumin level expressed in g/dL (the NAFLD fibrosis score calculator can also convert it from g/L).

The following NAFLD fibrosis score range is used to identify liver fibrosis:

A score lower than -1.455 can exclude advanced fibrosis with a high accuracy, whereas score higher than 0.676 is highly indicative of advanced fibrosis. Applying this model may help avoid unnecessary liver biopsy.