Reproducibility of transient elastography in the evaluation of liver fibrosis in patients with chronic liver disease

Objective: Transient elastography (TE) is gaining popularity as a non-invasive method for predicting liver fibrosis, but intraobserver and interobserver agreement and factors influencing TE reproducibility have not been adequately assessed. This study investigated these aspects. Setting: Tertiary referral liver unit. Patients: Over a 4-month period, 200 patients with chronic liver disease (CLD) with varying aetiology consecutively underwent TE and liver biopsy. Interventions: TE was performed twice by two different operators either concomitantly or within 3 days of the bioptic procedure (METAVIR classification). Main outcome measures: Intraobserver and interobserver agreement were analysed using the intraclass correlation coefficient (ICC) and correlated with different patient-related and liver disease-related covariates. Results: 800 TE examinations were performed, with an indeterminate result rate of 2.4%. The overall interobserver agreement ICC was 0.98 (95% CI 0.977 to 0.987). Increased body mass index (>25 kg/m²), steatosis, and low staging grades (fibrosis (F) stage <2) were significantly associated with reduced ICC (p<0.05). Intraobserver agreement ICC was 0.98 for both raters. Using receiver operating characteristic curves, three diagnostic TE thresholds were identified: >7.9 kPa for F≥2, >10.3 for F≥3 and >11.9 for F = 4. TE values assessed by the two raters fell within the same cut-off of fibrosis in 88% of the cases for F≥2, in 92% for F≥3 and 91% for F = 4. Conclusions: TE is a highly reproducible and user-friendly technique for assessing liver fibrosis in patients with CLD. However, because TE reproducibility is significantly reduced (p<0.05) in patients with steatosis, increased BMI and lower degrees of hepatic fibrosis, caution is warranted in the clinical use of TE as a surrogate for liver biopsy.