NAFLD Fibrosis Score Calculator
NAFLD Fibrosis Score Calculator
Estimate advanced fibrosis in fatty liver disease from age, BMI, glycaemic status, AST/ALT ratio, platelets and albumin.
NAFLD Fibrosis Score
6 inputs → scoreAge 55, BMI 32, diabetes present, AST 48, ALT 40, platelets 190, albumin 3.8 g/dL
Formula
- age
- years
- BMI
- kg/m²
- IFG/diabetes
- 1 if present, 0 if absent
- AST/ALT
- ratio of the two in U/L
- platelets
- ×10⁹/L
- albumin
- g/dL — divide g/L by 10
Worked example
Age 55, BMI 32, diabetes present, AST 48, ALT 40, platelets 190, albumin 3.8 g/dL
AST/ALT = 48 ÷ 40 = 1.20
−1.675 + (0.037×55) + (0.094×32) + 1.13 + (0.99×1.20) − (0.013×190) − (0.66×3.8)
= −1.675 + 2.035 + 3.008 + 1.130 + 1.188 − 2.470 − 2.508 = 0.708
Above 0.675 → advanced fibrosis likely
Thresholds
| Score | Interpretation | Predictive value |
|---|---|---|
| < −1.455 | Advanced fibrosis unlikely | NPV ≈ 93% |
| −1.455 to 0.675 | Indeterminate | — |
| > 0.675 | Advanced fibrosis likely | PPV ≈ 90% |
Using the score in a fatty liver pathway
The NAFLD fibrosis score was derived specifically in biopsied fatty liver disease, and unlike the more general indices it includes BMI and glycaemic status — the two metabolic drivers that determine who progresses. That makes it better calibrated than APRI in this population, though FIB-4 is simpler and performs comparably.
It is used the same way as FIB-4: as a rule-out test at the front of a pathway. A score below −1.455 makes advanced fibrosis unlikely enough to keep a patient in primary care, which is what a condition affecting a quarter of the adult population requires. A score above 0.675 warrants referral.
Two limitations matter in practice. About a third of patients land in the indeterminate band and need a second test regardless, so many pathways now run FIB-4 first and reserve elastography for the indeterminate and high groups. And like FIB-4, the score drifts upward with age because age is a positive term, so it over-calls fibrosis in older patients — the same caution that produced the age-adjusted FIB-4 threshold applies here, without an agreed correction.
Frequently asked questions
What albumin units does the NAFLD fibrosis score use?
g/dL. If your laboratory reports g/L, divide by 10 — an albumin of 38 g/L is 3.8 g/dL. Using g/L directly produces a wildly wrong score.
What counts as impaired fasting glucose for this score?
A fasting glucose of 100 mg/dL (5.6 mmol/L) or above, or an established diagnosis of diabetes. Either scores 1.
How does it compare with FIB-4?
Similar accuracy in fatty liver disease. FIB-4 needs fewer inputs and no BMI, so most pathways use it first; the NAFLD fibrosis score adds metabolic variables and is a reasonable second opinion.
What do I do with an indeterminate result?
Proceed to a second non-invasive test — transient elastography or an ELF blood test — rather than to biopsy. Around a third of patients score in this band.
Related calculators
References
- Angulo P et al. The NAFLD fibrosis score: a noninvasive system that identifies liver fibrosis in patients with NAFLD. Hepatology. 2007;45(4):846–54.
- EASL-EASD-EASO Clinical Practice Guidelines on the management of MASLD.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.