Agreement and Reliability of Transient Elastography

Previous studies have reported excellent test-retest reliability for transient elastography (TE) in viral hepatitis. Reliability refers the ability of an instrument to discriminate between study subjects and may be excellent even if considerable measurement-error exists, if the population is heterogenous. Agreement, in contrast, refers to differences of measurements on the original scale (kPa for TE). Whether agreement is acceptable is situation-dependent and can be related to the smallest detectable change (SDC). Agreement metrics or SDC have not been addressed in previous studies for chronic viral hepatitis. The aim of this study is to assess agreement, SDC, and reliability of repeated measurements of liver stiffness of TE in patients with chronic viral hepatitis, and to explore factors associated with disagreement.