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APRI (AST to Platelet Ratio Index)

AST-to-platelet ratio index for fibrosis and cirrhosis in chronic hepatitis C.

For healthcare professionalsLiverv1.0.0

For healthcare professionals / clinical use. Not a self-diagnosis tool.

Your measurements

U/L
U/L
×10⁹/L

Calculated on your device. Nothing is sent to a server.

Your result will appear here

Enter your measurements, then press Calculate.

Methodology

APRI (Wai 2003)

APRI = (AST ÷ AST ULN) ÷ platelets (×10⁹/L) × 100

Simple serum index validated in chronic hepatitis C; WHO uses > 2.0 to identify cirrhosis in resource-limited settings.

Who it is for
Adults with chronic hepatitis C (also used in hepatitis B).
Version
1.0.0

How this calculator works

Where the formula comes from

  • Wai and colleagues (2003) developed APRI in treatment-naive patients with chronic hepatitis C who had liver biopsy: a training set of 192 and a validation set of 78.[1]
  • APRI combines the opposing effects of fibrosis on AST (rising) and platelet count (falling); its AUROC was 0.80 for significant fibrosis and 0.89 for cirrhosis in the training set, and 0.88 and 0.94 in the validation set.[1]

The inputs

  • APRI = (AST ÷ AST upper limit of normal) ÷ platelet count (10⁹/L) × 100; the upper limit of normal is the laboratory's own value.[1]

Where accuracy falls (published evidence)

  • A 2011 meta-analysis of 40 studies (8,739 patients with hepatitis C) found summary AUROCs of 0.77 for significant fibrosis and 0.83 for cirrhosis, indicating moderate accuracy, and lower accuracy in HIV/HCV coinfection.[2]

What guidelines say

  • WHO hepatitis C guidance (2018) lists APRI low and high cut-offs of 0.5 and 1.5 for significant fibrosis and 1.0 and 2.0 for cirrhosis.[3]

Sources

  1. Wai CT, Greenson JK, Fontana RJ, et al. A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C. Hepatology. 2003;38(2):518–526. doi:10.1053/jhep.2003.50346
  2. Lin ZH, Xin YN, Dong QJ, et al. Performance of the aspartate aminotransferase-to-platelet ratio index for the staging of hepatitis C-related fibrosis: an updated meta-analysis. Hepatology. 2011;53(3):726–736. doi:10.1002/hep.24105
  3. World Health Organization. Guidelines for the care and treatment of persons diagnosed with chronic hepatitis C virus infection. Geneva: WHO; 2018. https://www.ncbi.nlm.nih.gov/books/NBK531733/

Compiled from the published sources above. Every statement was agreed independently by three AI research tools (Claude, ChatGPT, DeepSeek) and its source verified in PubMed or Crossref by the Hakeemly editorial team. Not reviewed by a doctor unless stated. Agreed on

Worked example: how to calculate APRI

Inputs

AST
96 U/L
AST upper limit of normal
40 U/L
Platelet count
100 ×10⁹/L

Result

APRI
2.4

Over 2.0: suggests cirrhosis (WHO hepatitis C guidance)

An illustration with sample values, worked out with the same method the tool above uses.

Limitations

  • Moderate accuracy; many patients fall in the indeterminate zone.

References

  1. Wai CT, Greenson JK, Fontana RJ, et al. A simple noninvasive index can predict both significant fibrosis and cirrhosis in patients with chronic hepatitis C. Hepatology. 2003;38(2):518–526. doi:10.1053/jhep.2003.50346

Continue with your measurements

Shared measurements carry over automatically, in this tab only.

For healthcare professionals

Child–Pugh Score

Severity of cirrhosis from bilirubin, albumin, INR, ascites and encephalopathy.

Professional~2 min

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