AST to Platelet Ratio Index (APRI)
Patients with hepatitis C being considered for liver biopsy to determine chance of fibrosis or cirrhosis.
- 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.
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.
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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.
We are unaware of validated management algorithms using the APRI.
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.
APRI = (AST in IU/L) / (AST Upper Limit of Normal in IU/L) / (Platelets in 109/L)
Facts & Figures
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.
Original/Primary ReferenceWai 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):518-26.
ValidationKhan DA, Fatima Tuz Z, Khan FA, Mubarak A. Evaluation of diagnostic accuracy of APRI for prediction of fibrosis in hepatitis C patients. J Ayub Med Coll Abbottabad 2008; 20: 122-126.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;53:726-36.
From the Creator
Why did you develop the APRI? Was there a particular clinical experience or patient encounter that inspired you to create this tool for clinicians?
We developed the APRI to find a simple, no cost method to estimate liver fibrosis and cirrhosis severity that can be applied in any part of the world.
What pearls, pitfalls and/or tips do you have for users of the APRI? Do you know of cases when it has been applied, interpreted, or used inappropriately?
APRI provides an estimation. It is not gospel, and users need to understand the limitations. For example, when the APRI result is discordant from other clinical data, one should consider repeating the assessment again during follow up, and take into account all available evidence. APRI has better negative predictive value than positive predictive value, i.e., low APRI is reliable in ruling out cirrhosis, but APRI is not very sensitive in identifying cirrhosis.
What recommendations do you have for doctors once they have applied the APRI? Are there any adjustments or updates you would make to the score based on new data or practice changes?
Knowing whether patients have advanced fibrosis or cirrhosis can determine urgency of treatment and need for cirrhosis care, e.g. HCC surveillance.
How do you use the APRI in your own clinical practice? Can you give an example of a scenario in which you use it?
If I see a patient in clinic with no biopsy, no decompensation, no imaging, no elastography, I can estimate in my head APRI as long as I have AST and platelet count, and can make good estimate of the stage of liver disease.
With the advent of and increasing access to DAAs for hepatitis C, how close are we to eradicating the disease?
We cannot eradicate hepatitis C until we have a vaccine, but we can eliminate it if we are able to find everyone who is infected and get them started on treatment.
Any research you have in the pipeline that you’re particularly excited about?
About the Creator
Anna S. Lok, MD, FAASLD, is a hepatology research professor and assistant dean for clinical research in the internal medicine department at the University of Michigan. She is also director of clinical hepatology at the University of Michigan Health System and the immediate past-president of the American Association for the Study of Liver Diseases. Dr. Lok’s research focuses primarily on the history and treatment of hepatitis B and C, hepatocellular carcinoma, and nonalcoholic fatty liver disease.
To view Dr. Anna S. Lok's publications, visit PubMed