AST to Platelet Ratio Index (APRI)

Why Use

There is no perfect method for predicting fibrosis and cirrhosis in HCV and the APRI uses commonly available laboratory values that may help avoid the need for liver biopsy. The FIB-4 Score may also be useful in these patients as well.

When to Use

Patients with hepatitis C being considered for liver biopsy to determine chance of fibrosis or cirrhosis.

Formula

Pearls / Pitfalls

TThe AST to Platelet Ratio Index (APRI) predicts fibrosis and cirrhosis in hepatitis C patients. It offers a non-invasive way to predict which patients have cirrhosis without imaging or biopsy. Points to keep in mind: Most experts recommend using the AST Platelet Ratio Index in conjunction with other non-invasive testing especially with intermediate values, as sensitivity and specificity may not be sufficient at these values. Caution: If your laboratory has higher-than-typical upper limits of normal for AST this could alter diagnostic performance.

Management

We are unaware of validated management algorithms using the APRI.

Critical Actions

The APRI is validated in HCV referral populations, thus extending it to other conditions or populations may be misleading. Upper reference values for AST vary by laboratory, which can also significantly affect results.

Advice

This index is among the best validated methods for predicting HCV progression. At extreme values (very high or very low) the APRI can avoid further invasive testing in a substantial proportion of patients. Unfortunately, findings in validation studies suggest only moderate predictive value.

More Information

Based on 2011 meta-analysis in Hepatology by Lin et. al: Significant fibrosis : APRI threshold of 0.7 was 77% sensitive and 72% specific. Severe fibrosis : APRI threshold of 1.0 was 61% sensitive and 64% specific. Cirrhosis : APRI threshold of 1.0 was 76% sensitive and 72% specific.