Agreement and Reliability of Transient Elastography

Study Overview
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Brief Summary
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The aim of this study is to assess agreement, smallest detectable change, and reliability of repeated measurements of liver stiffness of transient elastography in patients with chronic viral hepatitis, and to explore factors associated with disagreement.

Detailed Description
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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.

Official Title
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Agreement and Reliability of Transient Elastography in Patients With Chronic Viral Hepatitis - a Cross-sectional Test-retest Study

Conditions
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Chronic Viral Hepatitis

Intervention / Treatment
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* Diagnostic Test: Transient elastography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients at the departments of infectious diseases in Malmö, Lund and Helsingborg with chronic viral hepatitis. Adult patients Signed informed consent to participate in the study. Exclusion Criteria: suspected or confirmed pregnancy. patients unable to speak Swedish inability to sign informed consent.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Chronic viral hepatitis<br> | Diagnostic Test: Transient elastography<br>* Transient elastography measures liver stiffness in kPa<br>* Other names: Fibroscan;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Disagreement defined as a difference in TE results between operators in KPa of ≥ 33%, as well as the smallest detectable change, SDC95. | Disagreement, expressed as 1) the proportion of participants with inter-rater differences at or above our prespecified threshold (33%) and 2) the smallest detectable change, representing the difference needed to state with 95% certainty that a change had occurred in the underlying fibrosis (SDC95). | Assessed at a 30 min visit to the outpatient clinic | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reliability, estimated using the intra-class correlation | Reliability, for continuous stiffness measurements as well as for different fibrosis stage categories. | Assessed at a 30 min visit to the outpatient clinic | 
| Patient and exam characteristics associated with inter-rater differences above our prespecefied threshold. | As an exploratory outcome, patient and exam characteristics associated with inter-rater differences above our prespecified threshold of ≥ 33% in liver stiffness will be evaluated. These characteristics include patients age, hepatitis b staging, BMI, biomarkers including Alanine transaminase, probe type, (medium or XL-probe) viral load, alkaline phosphatase, bilirubin, albumin, prothrombin time/international normalized ratio, time since food (hours), time since alcohol (hours), previous liver biopsy (years) | Assessed at a 30 min visit to the outpatient clinic |