Age and platelet count: a simple index for predicting the presence of histological lesions in patients with antibodies to hepatitis C virus

The aim of this study was to identify clinical and biological factors associated with histological lesions in patients with chronic hepatitis C and to construct a simple diagnostic index. A database consisting of 500 patients with untreated biopsy-proven chronic non-A non-B hepatitis was used. Liver biopsies were reviewed, blind, by a panel of pathologists. Patients were classified according to the presence of necroinflammatory lesions (histological activity) and fibrosis. The diagnostic value of nine clinical and 10 biological factors was assessed using logistic regression analysis, sensitivity, specificity and predictive values, and a score was constructed combining the most significant factors identified. The validation used an independent population of 120 patients. Serum platelet concentration and age were the two main factors significantly and independently correlated with the presence of fibrosis and/or histological activity. A simple score referred to as AP, combining age and platelet count, varied from 0-10. For the presence of significant histological disease (moderate to severe necroinflammatory lesions and/or septal fibrosis to cirrhosis), an AP score of 6 or more had a specificity of 0.93 and a sensitivity of 0.52%. In the validation population, the area under the curve was 0.690 +/- 0.085, not significantly different from that of the first population, 0.763 +/- 0.043. Hence, a simple score combining age and platelet count enabled the accurate prediction of the presence of activity and fibrosis in patients infected with the hepatitis C virus. When this score reached 6, liver biopsy could be avoided owing to its high predictive value. However, the negative predictive value was not high enough to prevent a liver biopsy in patients with a lower score.