By Liz Highleyman - hivandhepatitis.com
Liver biopsy is considered the "gold standard" for assessing liver fibrosis, but the procedure is expensive, uncomfortable, and associated with a small risk of complications. Thus, researchers have explored various non-invasive methods for monitoring fibrosis progression.
One technique, FibroScan, uses transient elastometry to measure liver stiffness. Numerous studies conducted in patients with chronic hepatitis C have shown that transient elastometry can distinguish absent or mild fibrosis from severe fibrosis or cirrhosis. Two recent studies looked at how well the method performs in patients with acute viral hepatitis and those with recurrent HCV after liver transplantation.
Post-transplant HCV
In the first study, reported in the January 24, 2008 advance online edition of Gut, another Italian research team used transient elastometry to evaluate liver disease progression in 95 patients who received liver transplants due to end-stage liver disease related to hepatitis C.
Paired liver biopsies and transient elastometry were performed 6 to 156 months (median 35) after liver transplantation; 40 patients with recurrent hepatitis C were sequentially evaluated 6 to 21 months apart.
Results
The median overall transient elastometry value was 7.6 kiloPascals (kPa) in the 90 patients with a successful examination:
5.6 kPa in the 30 patients with Ishak fibrosis scores of F0-F1;
7.6 kPa in the 38 subjects with F2-F3;
16.7 kPa in the 22 patients with F4-F6.
The areas under receiver operating characteristic (ROC) curves were 0.85 for patients with stage F3 or higher and 0.90 for F4 or higher.
7.9 and 11.9 kPa were the optimal transient elastometry cut-off values (81% and 82% sensitivity, 88% and 94% negative predictive value, respectively).
liver fibrosis, necroinflammatory activity, and gamma-glutamyl transpeptidase (GGT) levels above 200 IU/L independently influenced transient elastometry results.
During post-transplant follow-up, transient elastometry results changed in parallel with liver disease grading and staging, showing 86% sensitivity and 92% specificity in predicting staging increases.
Based on these findings, the authors wrote, "Transient elastography accurately predicts fibrosis progression in liver transplant patients with recurrent hepatitis C, suggesting that protocol liver biopsy might be avoided in patients with improved or stable transient elastography values during follow-up."
Reference C Rigamonti, MF Donato, M Fraquelli, and others. Transient elastography predicts fibrosis progression in patients with recurrent hepatitis c after liver transplantation. Gut. January 24, 2008 [Epub ahead of print].
Acute HCV
In the second study, described in the February 2008 issue of Hepatology, Italian researchers evaluated 18 patients without a previous clinical history of liver disease who were admitted for acute viral hepatitis. In all patients, aminotransferase (ALT, AST) levels were measured and liver stiffness was determined on the same study day at 3 time points:
Peak aminotransferase increase;
Aminotransferase levels 50% or less of the peak;
Aminotransferase levels 2 times the upper limit of normal or less.
Results
In all patients, the degree of liver stiffness at the time of peak aminotransferase increase exceeded the proposed cut-off values for significant fibrosis or cirrhosis.
A progressive reduction in liver stiffness values was observed during the follow-up period, in parallel with the decline in aminotransferase levels.
A statistically significant positive correlation was found between aminotransferase levels and liver stiffness measurements at the onset of acute viral hepatitis (R = 0.53 for ALT, R = 0.51 for AST).
In conclusion, the authors wrote, the extent of necroinflammatory activity needs to be carefully considered in future studies aimed at further validating transient elastography, particularly in patients with absent or low-stage liver fibrosis" (Metavir stages F0-F2).
They added that, "Liver stiffness measurement does not represent a reliable instrument to detect the presence of advanced fibrosis and cirrhosis in patients presenting with a clinical picture of acute hepatitis."
Reference
U Arena, F Vizzutti, G Corti, and others. Acute viral hepatitis increases liver stiffness values measured by transient elastography. Hepatology 47(2): 380-384. February 2008.
