NAFLD Fibrosis Score Calculator
Estimate liver fibrosis severity in non-alcoholic fatty liver disease (NAFLD) using age, BMI, lab values, and diabetes status.
Understanding the NAFLD Fibrosis Score (NFS)
The NAFLD Fibrosis Score (NFS) is a validated, non-invasive clinical scoring system designed to estimate the presence of advanced liver fibrosis (stages F3-F4 or cirrhosis) in patients with non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD).
By utilizing routinely available clinical and laboratory parameters (age, BMI, diabetes status, AST/ALT ratio, platelet count, and serum albumin), the NFS helps clinicians identify patients who require further diagnostic workup while sparing low-risk individuals from unnecessary invasive liver biopsies.
The NAFLD Fibrosis Score Formula
NFS = -1.675 + (0.037 × Age) + (0.094 × BMI) + (1.13 × IFG/Diabetes) + (0.99 × AST/ALT Ratio) - (0.013 × Platelets [×10⁹/L]) - (0.66 × Albumin [g/dL])
Score Interpretation and Clinical Cutoffs
| NFS Range | Risk Category | Predictive Interpretation |
|---|---|---|
| < -1.455 | Low Risk | F0 to F2 fibrosis (Advanced fibrosis ruled out; Negative Predictive Value > 90%) |
| -1.455 to 0.675 | Indeterminate Risk | Intermediate risk score; further non-invasive testing (e.g. FibroScan) indicated |
| > 0.675 | High Risk | F3 to F4 advanced fibrosis / cirrhosis (Positive Predictive Value > 80%) |
Clinical Applications and Guidelines
Major gastroenterology and hepatology practice guidelines (including AASLD and EASL) recommend utilizing non-invasive fibrosis scores like the NAFLD Fibrosis Score and the FIB-4 index to screen primary care and endocrinology patients with fatty liver disease.
Frequently Asked Questions
What parameters are required to calculate the NAFLD Fibrosis Score?
The calculation requires six clinical variables: age, body mass index (BMI), presence of impaired fasting glucose or type 2 diabetes, AST level, ALT level, platelet count, and serum albumin.
What does an indeterminate NAFLD Fibrosis Score mean?
An indeterminate score (between -1.455 and 0.675) means the test cannot definitively confirm or exclude advanced fibrosis. Clinical guidelines recommend secondary non-invasive testing such as Transient Elastography (FibroScan) or consultation with a hepatologist.
How accurate is the NAFLD Fibrosis Score?
The NAFLD Fibrosis Score has a negative predictive value exceeding 90% for ruling out advanced fibrosis when the score is below -1.455, making it an excellent primary screening tool in clinical practice.
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