Operator Variability in Transient Elastography for Liver Fibrosis Prediction

In patients with chronic hepatitis C virus (HCV) infection, transient elastography for the prediction of liver fibrosis has inter-observer variability that may not be negligible, according to study results published in the Annals of Hepatology.

The study included participants age ≥18 years with chronic HCV infection (n=356). Participants were examined by 2 operators on the same day. Each operator performed transient elastography to estimate liver fibrosis, using the FibroScan guide to identify a portion of the liver for examination that was at least 60 mm thick and free of large vessels.

The researchers found an overall inter-observer agreement intra class correlation coefficient of .921; 95% CI, .903-.936. They also found a reliable correlation between the 2 operators (Spearman’s value q=.808; P <.001).

There was a significant difference between the median values of liver stiffness measurement from the first and second exams (6.8 kPa for the first operator vs 7.6 kPa for the second operator; P =.002).

The results indicated a non-negligible discordance of fibrosis staging between the 2 operators (87 cases; 24.4%). Discordance of at least 1 stage occurred in 16.9% (n=60) cases and discordance of two or more stages occurred in 7.6% (n=27) of cases. The researchers calculated an inter-observer reliability value of κ=.557 (P <.001). This high rate of discrepancy is highlighted because of its impact on the management of chronic HCV classification of mild fibrosis by an operator as an indicator for antiviral treatment in many countries. Discordance between operators was found in 4.2% of participants, demonstrating that 20% of patients in this study may need a change in treatment plan. The researchers found that obesity (body mass index ≥30 kg/m²) was the main factor associated with discordance (P=.002).

“[Transient elastography] is a user-friendly non-invasive technique,; however, its performance may be altered by high body mass index, which affects both the feasibility and reproducibility of the test,” the researchers wrote. However, they also concluded with a reminder of the importance of careful analysis of transient elastography by experts.

Reference

Shiha GE, El-Etreby S, Bahgat M, et al. Chronic hepatitis C patients with obesity: do we need two operators for accurate evaluation of liver stiffness? Ann Hepatol. 2018;17(5):795-801