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New research highlights the ongoing need for more studies on the acceptability and reliability of transient elastography in screening patients for fibrosis stage and cirrhosis in patients with chronic hepatitis C virus (HCV) infections.¹

A team, led by Oskar Ljungquist, Department of Infectious Diseases, Helsingborg Hospital, assessed interrater agreement and reliability of transient elastography measurements.

“Early identification of fibrosis and cirrhosis of the liver enables prevention and treatment of long-term consequences of chronic hepatitis C, including liver failure, hepatocellular cancer, and death,” the authors wrote. “Even where antiviral treatment is generally offered, fibrosis and cirrhosis staging affect decisions regarding surveillance, for hepatocellular cancer and esophageal varices.”

Transient Elastography

Transient elastography is a method largely used to evaluate fibrosis stage and cirrhosis in patients with chronic hepatitis C. This has generally replaced liver biopsies as the diagnostic tool of choice.

In previous research, investigators have found excellent reliability of transient elastography in patients with HCV. There also has been comparable accuracy between liver biopsies and transient elastography in detecting fibrosis in this patient population. However, agreement metrics have not been evaluated. Overall, there were 255 examinations performed and 130 measurements used for interrater analysis and 250 used for interrater analysis.

In the study, a pair of operators performed transient independently, directly after each other.

Outcomes

The investigators sought primary outcomes of disagreement, defined as a difference in transient elastography results between operators of at least 33% and the smallest detectable change, SDC₉₅ (the difference between measurements needed to state with 95% certainty that there is a difference in underlying stiffness).

The team also looked at various secondary outcomes, including reliability, measured as intraclass correlation (ICC) and patient and examination characteristics linked to the agreement.

The study included 65 patients with a mean liver stiffness of 9.7 kPa, 32% (n = 21) had a disagreement in transient elastography of at least 33% between the 2 operators. The SDC₉₅ on the log scale was 1.97. This shows that a nearly two-fold increase or decrease in liver stiffness would be required to confidently represent a change in the underlying fibrosis.

There were 23 patients classified into different fibrosis scores by the 2 operators, of which 12% (n = 8) had a F4 discrepancy.

Interrater disagreement at or above the prespecified threshold of 33% was identified in 32% (n = 21).

Using the ICC, reliability was 0.86, which was considered acceptable.

In the post-hoc analysis, the investigators found fasting less than 5 hours before transient elastography was linked to a higher degree of disagreement, 48% compared to 19% (P = 0.03).

“In our clinical setting, interrater agreement in directly repeated TE measurements was surprisingly low. It is essential to further investigate the reliability and agreement of TE to determine its validity and usefulness,” the authors wrote.