Measuring liver stiffness using transient elastography can predict severe portal hypertension in patients with hepatitis C-related cirrhosis.

As liver disease progresses, fibrosis leads to portal hypertension which causes potentially lethal complications such as variceal hemorrhage, ascites and portosystemic encephalopathy. Measuring the hepatic venous pressure gradient ( HVPG ) is the standard method used to assess portal 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, of the University of Florence, sought to evaluate transient elastography, a rapid, non-invasive technique to measure 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 researchers studied 61 consecutive patients with diagnosed or suspected cirrhosis from chronic HCV infection. Each patient underwent transient elastography to measure 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 report. The correlation was excellent for HVPG values less than 10 or 12 mmHg, but not as good for greater HVPG values. They 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 percent and 77 percent 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 conclude.

An accompanying editorial by Joseph Lim of Yale University School of Medicine and Roberto Groszmann of VA Connecticut Healthcare System and Yale University applauds 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 editorial authors note, particularly because the average BMI ( Body Mass Index ) of the study population was 23, which contrasts to higher mean BMIs in the U.S. population. To date HVPG still is the gold standard.. for predicting clinical decompensation and the response of portal pressure to pharmacological therapy.

Source: Hepatology, 2007

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