Bonacini et al used 4 laboratory tests to calculate a discriminant score capable of identifying a patient with chronic viral hepatitis C resulting in cirrhosis. This may be helpful in evaluating patients who cannot undergo liver biopsy.
Parameters:
(1) International normalized ratio (INR) for the prothrombin time (PT)
(2) serum ALT to serum AST ratio
(3) platelet count
ratio of ALT to AST =
= (serum ALT) / (serum AST)
Parameter
Findings
Points
INR
< 1.1
0
1.1 - 1.4
1
> 1.4
2
ALT to AST ratio
> 1.7
0
1.2 - 1.7
1
0.6 - 1.19
2
< 0.6
3
platelet count
> 340,000 per µL
0
280,000 - 340,000 per µL
1
220,000 - 279,999 per µL
2
160,000 - 219,999 per µL
3
100,000 - 159,999 per µL
4
40,000 - 99,999 per µL
5
< 40,000 per µL
6
discriminant score =
= SUM(points for all 3 measures)
Interpretation:
• minimum discriminant score: 0
• maximum discriminant score: 11
• A score > 3 (>= 4) had the best sensitivity and specificity for cirrhosis.
• In the data of Gordon et al, patients with cirrhosis had a score of 5 +/-2 and those without cirrhosis had a score of 3 +/- 1. This would mean a score of 0 or 1 was not associated with cirrhosis, a score >= 6 with cirrhosis, and 2 to 5 indeterminate.
Performance:
• The sensitivity at cutoff > 3 was 74% and specificity was 63%.
• The positive predictive value for cirrhosis was 46%.
Limitations:
• The test cannot be used in a patient being treated with warfarin or with thrombocytopenia due to a non-hepatic cause.
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