Ultrasound Helps Predict Liver Damage in NAFLD

Ultrasound Helps Predict Liver Damage in NAFLD
By Chris Emery, Contributing Writer, MedPage Today
Published: January 29, 2010
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner Earn CME/CE credit
for reading medical news
Action Points

* Note that transient elastography appears to accurately detect advanced stages of fibrosis in patients with non-alcoholic fatty liver disease.


* Note that a commentator argued that the technique requires further validation before being adopted as a common diagnostic method.

An ultrasound technique called transient elastography can accurately detect liver damage in most patients with non-alcoholic fatty liver disease (NAFLD), a condition that often accompanies obesity and type 2 diabetes, a new study found.

Transient elastography (TE) accurately measured levels of liver stiffness, an indication of the amount of fibrosis, in more than 97% of patients with a body mass index below 30 kg/m2 and in 75% of obese patients, according to a report in the February issue of Hepatology.

"The adoption of transient elastography could potentially spare two-thirds of NAFLD patients from liver biopsies," Victor de Lédinghen, MD, PhD, of Hôpital Haut-Lévêque, in Pessac Cedex, France, and colleagues wrote. "Since the prevalence of NAFLD is high in many affluent countries, this approach would be cost saving."

Non-alcoholic fatty liver disease has become more common as the incidence of metabolic syndrome and obesity has grown. The condition can progress to cirrhosis and hepatocellular carcinoma, particularly among patients with non-alcoholic steatohepatitis (NASH), in which fat in the liver causes inflammation and tissue damage.

Liver biopsy is typically used to determine levels of inflammation and fibrosis associated with NASH, but the procedure carries a small risk of hemorrhage, puncture of other internal organs, infection, and spread of cancer cells. Transvenous liver biopsy carries an additional risk of adverse reaction to the contrast material.

These problems, in addition to the mixed results due to sampling variance biopsies sometimes deliver, have researchers searching for alternative methods of determining the extent of liver fibrosis.

Lédinghen and colleagues compared the accuracy of TE to biochemical tests for the diagnosis of fibrosis and cirrhosis in 246 NAFLD patients who underwent liver biopsies between May 2003 and April 2009 at University Hospital of Pessac and Prince of Wales Hospital in Hong Kong. The accuracy of the TE measurements was validated by biopsy results.

Of the patients, 31 (12.6%) had advanced fibrosis and 25 (10.2%) had cirrhosis.

The liver stiffness measurements of patients with F0, F1, F2, F3, and F4 stages of fibrosis were 5.7, 6.8, 7.8, 11.8, and 25.1 kPa, respectively (P<0.0001, by analysis of variance).

TE was accurate for predicting fibrosis in patients with liver stiffness of at least 7.9 kPa; measurement and accuracy were not affected by hepatic steatosis, necroinflammation, and obesity.

The most disagreement between the results of the TE and biopsy methods occurred in patients with short liver biopsy lengths and mild or no fibrosis.

In patients with complete biochemical data, the accuracy of TE was compared with that of other means of predicting liver stiffness, and was found to be more reliable than aspartate aminotransferase–to–alanine aminotransferase ratio, aspartate aminotransferase–to–platelet ratio index, FIB-4, BARD, and NAFLD fibrosis scores.

The authors cautioned that the results of the liver biopsies potentially could have been influenced by sampling bias and that referral patients enrolled in the study may have had more advanced liver disease than the general population. They also noted that a significant proportion of obese patients were not analyzed because a liver stiffness measurement could not be obtained.

In an accompanying editorial, Leon Adams, PhD, of the University of Western Australia, noted that the majority of individuals with NAFLD will not develop liver-related morbidity or die from liver disease.

"Thus, he wrote, "the difficulty facing the managing physician is predicting which patients are at greatest risk of developing cirrhosis, thus identifying those who will benefit most from specific treatments, more intensive therapy, and monitoring."

The new study, he wrote, suggests that TE is effective at excluding advanced fibrosis and cirrhosis in patients with NAFLD. However, he argues that the technique requires further validation in obese and morbidly obese populations and that sensitivity of the test is likely to vary between differing patient populations, different medical personnel administering the test, and underlying prior probability of fibrosis.

"Lastly," he concluded, "if noninvasive markers are going to form part of the routine assessment of the millions of individuals with NAFLD, the expense and availability of each modality may play a decisive role in which the noninvasive method is most appropriately taken up by community physicians and specialty hepatologists."

The study was supported by the Chinese University of Hong Kong.

Co-investigator Henry Lik-Yuen Chan reported receiving advising and speaking fees from Novartis, Bristol-Myers Squibb, Pharmasset, and Schering-Plough.

Co-investigator Sung reported receiving advising and speaking fees from AstraZeneca, GlaxoSmithKline, and Roche.

Primary source: Hepatology
Source reference:
de Ledinghen V, et al "Diagnosis of fibrosis and cirrhosis using liver stiffness measurement in nonalcoholic fatty liver disease" Hepatology 2010; 51: 454-62.

Additional source: Hepatology
Source reference:
Adams L "Transient elastography in NAFLD: Making sense of echos" Hepatology 2010; 51: 370-72.