Wai et al developed a number of models for predicting fibrosis and cirrhosis in patients with chronic viral hepatitis C (HCV). The authors are from the University of Michigan
Independent predictors of fibrosis from multivariate analysis:
(1) platelet count
(2) serum AST
(3) serum alkaline phosphatase
Independent predictors of cirrhosis from multivariate analysis:
(4) white blood cell count
(5) AST to ALT ratio
Models using AST and platelet count only were comparable to ones with more variables.
Parameters used in models:
(1) serum AST in IU/L
(2) upper limit of normal reference range for AST
(3) platelet count (as factor * 10^9/L)
AST to platelet ratio index = APRI =
= ((serum AST) / (upper limit of normal for AST)) / (factor from platelet count) * 100 =
= 100 * (serum AST) / ((upper limit normal AST) * (factor for platelet count))
risk score for significant fibrosis =
= 2.318 + (0.274 * LN((serum AST) / (upper limit of normal))) - 0.375 * LN(factor for platelet count))
risk score for cirrhosis =
= 2.411 + (0.1 * LN((serum AST) / (upper limit of normal))) - 0.463 * LN(factor for platelet count))
• Different cutoff values for the APRI are used for fibrosis and cirrhosis.
• The cutoffs for the two risk scores were not given (page 521). My guess is that a negative number is against the diagnosis and a positive number if for.
0.51 to 1.50
1.01 to 2.00
fibrosis absent, cirrhosis absent
0.51 - 1.00
fibrosis indeterminate, cirrhosis absent
1.01 - 1.50
fibrosis indeterminate, cirrhosis indeterminant
1.51 to 2.00
fibrosis present, cirrhosis indeterminant
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Purpose: To evaluate a patient with chronic viral hepatitis C for fibrosis and cirrhosis using the AST to platelet ratio index (APRI) and other models of Wai et al.
Specialty: Gastroenterology, Infectious Diseases
Objective: risk factors, laboratory tests, disease progression
ICD-10: B18.2, K74.0, K74.6,