Transient Elastography as a Non-invasive Method for Predicting Portal Hypertension in Patients with Hepatitis C-related Cirrhosis

Measuring liver stiffness using transient elastography can predict severe portal hypertension in patients with hepatitis C-related cirrhosis, according to a new study in the May 2007 issue of Hepatology. 

As liver disease progresses, fibrosis leads to portal hypertension (increased pressure in the portal vein carrying blood from the digestive tract to the liver), which can cause potentially lethal complications such as variceal hemorrhage, ascites, and hepatic encephalopathy.

Measuring the hepatic venous pressure gradient (HVPG) is the standard method used to assess portal vein pressure and predict its complications; however, the procedure is invasive, expensive, and requires technical expertise.

In search of another way to assess liver fibrosis and portal hypertension, researchers led by Massimo Pinzani, MD, PhD, of the University of Florence in Italy sought to evaluate transient elastography (also known as FibroScan), a rapid, non-invasive technique for measuring liver stiffness. They compared its accuracy in detecting portal hypertension and its complications with that of HVPG measurement.

Between March 1, 2005 and July 1, 2006, the investigators studied 61 consecutive patients with diagnosed or suspected cirrhosis related to chronic hepatitis C virus infection. Each patient underwent transient elastography to assess liver stiffness. Immediately afterward, they underwent HVPG measurement and liver biopsy. The researchers then analyzed the data and compared the diagnostic tools.

“Considering the whole patient population, a statistically significant, positive correlation between HVPG and liver stiffness measurement was found,” they reported.

The correlation was excellent for HVPG values less than 10 or 12 mmHg, but not as good for higher HVPG values. The researchers also noted a correlation between liver stiffness measurement and the presence of esophageal varices; however, the negative and positive predictive values for the detection of varices were unsatisfactory, at 66% and 77%, respectively.

“We suggest that measurement of liver stiffness by transient elastography may represent a reliable non-invasive methodology for the prediction of clinically significant and severe portal hypertension, although not good enough to replace endoscopy for the detection of varices,” the authors concluded.

An accompanying editorial by Joseph Lim of Yale University School of Medicine and Roberto Groszmann of the VA Connecticut Healthcare System and Yale University applauded the study as the first to evaluate the correlation between liver stiffness measurement and clinically significant portal hypertension as reflected by both direct HVPG measurement and the identification of esophageal varices on upper GI endoscopy.

“Additional validation studies evaluating its diagnostic accuracy in a representative American population are needed prior to regulatory approval and wide application to clinical practice,” the authors of the editorial noted, particularly given that the average body mass index (BMI) of the study population was 23, compared to higher mean BMIs in the U.S. population; transient elastrography works less well in overweight or obese individuals.

To date, HVPG remains the “gold standard” for predicting clinical liver decompensation and the response of portal pressure to pharmacological therapy.

05/18/07

Reference

F Vizzutti, U Arena, R Romanelli, and others. Liver Stiffness Measurement Predicts Severe Portal Hypertension in Patients with HCV-Related Cirrhosis. Hepatology. May 2007.

Hepatology is the official journal of the American Association for the Study of Liver Diseases (AASLD). Published by John Wiley & Sons, Inc., Hepatology is available online via Wiley InterScience at http://www.interscience.wiley.com/journal/hepatology