APRI Calculator
Calculate the AST to Platelet Ratio Index (APRI) — a non-invasive screen for significant liver fibrosis and cirrhosis.
What is APRI?
The AST to Platelet Ratio Index (APRI) is a simple, blood-test-based score used to screen for advanced liver fibrosis without a biopsy. First proposed by Wai et al. in 2003 for hepatitis C, APRI has since been validated across multiple chronic liver conditions including hepatitis B and non-alcoholic fatty liver disease. It is now part of WHO and AASLD non-invasive staging algorithms.
How is it calculated?
APRI = (AST / AST upper-limit-of-normal × 100) / Platelet count (×10⁹/L). Common interpretation: < 0.5 makes significant fibrosis unlikely, > 1.5 makes it likely, in-between is indeterminate. Many guidelines use a cut-off of 1.0 for cirrhosis screening.
Frequently Asked Questions
- Does APRI replace a biopsy?
- No — biopsy remains the gold standard, but APRI can rule out or strongly suggest fibrosis non-invasively.
- What is a normal AST upper limit?
- Typically 35–40 U/L; check your lab's reference range.
- How accurate is APRI?
- About 70–80% sensitivity for significant fibrosis, depending on aetiology.
- Should APRI be used alone?
- No — combine with FIB-4 and clinical assessment.