Reuters Health Information (2010-01-29): Transient elastography cuts liver biopsy rate in non-alcoholic steatohepatitis
Transient elastography cuts liver biopsy rate in non-alcoholic steatohepatitis
Last Updated: 2010-01-29 13:30:18 -0400 (Reuters Health)
HONG KONG (Reuters Health) - A device that noninvasively measures liver stiffness can help avoid biopsies in patients with non-alcoholic steatohepatitis (NASH), according to a joint Hong Kong Chinese-French study.
The device uses a technique called transient elastography. A mechanical pulse generated at the skin surface is propagated through the liver. The velocity of the wave, as measured by ultrasound, correlates with the stiffness of the liver, which in turn reflects the stage of fibrosis
Screening with transient elastography could potentially spare two in three NASH patients from biopsy, the researchers believe.
At a press briefing, principal investigator Dr. Vincent Wai-sun Wong of the Chinese University of Hong Kong said that a liver stiffness measurement of 7.9 kilopascals (kPa) or more indicates severe liver fibrosis.
In the study he and his colleagues will be reporting in the February issue of Hepatology, liver stiffness measurements "were not affected by age, gender, race, liver fat and body mass index", Dr. Wong said in an e-mail interview with Reuters Health.
"Ultrasound scans can only detect cirrhosis when the liver is shrunken or there are signs of cirrhotic complications. By contrast, transient elastography is sensitive enough to detect moderate to severe liver fibrosis," he noted.
Between 2003 and 2009, Dr. Wong and his coauthors recruited patients with NASH from the Prince of Wales Hospital in Hong Kong (n=118) and the University Hospital of Pessac in France (n=128). The study subjects had been referred to these centers for liver biopsy. Patients with viral hepatitis and other chronic liver diseases were excluded from the study.
Most of the patients were overweight; only 63 (25.6%) had a body mass index less than 25 kg/m2. Eighty-nine patients were diabetic and 99 were hypertensive.
Based on their biopsy results, 190 (77%) of the patients had mild fibrosis and 56 (23%) had severe fibrosis.
In 148 patients (60%), liver stiffness measurements were below the 7.9 kPa cutoff, indicating mild disease; biopsy results were correlated in 97% of these cases.
In the other 98 patients (40%), with measurements above the cutoff, severe fibrosis was confirmed in 52% on biopsy.
Mean liver stiffness measurements were 5.7 kPa with F0 (no fibrosis), 6.8 kPa with F1 (mild fibrosis), 7.8 kPa with F2 (moderate fibrosis), 11.8 kPa with F3 (advanced fibrosis) and 25.1 kPa with F4 (cirrhosis) (p<0.0001).
"Its accuracy in detecting early cirrhosis is excellent. Since treatment for most chronic liver diseases should be started at the stage of significant liver fibrosis, transient elastography would improve the ability of clinicians to identify this situation," Dr. Wong said.
"Although the distinction between no fibrosis and mild fibrosis is less clear, at least 60% of our patients would have been classified as low risk and not need a liver biopsy," he emphasized.
The device used in the study (Fibroscan, Echosens) is not yet approved by the FDA and is not in any clinical trials in North America.