The XL probe: A luxury or a necessity? Risk stratification in an obese community cohort using transient elastography.

Background: Transient elastography is a non-invasive tool which can stratify patients at risk of chronic liver disease. However, a raised body mass index has been independently associated with a failed or unreliable examination.

Objective: The purpose of this study was to analyse the performance of two probes (M/XL) on a portable transient elastography device within an obese community population.

Method: The method involved a prospective study with recruitment from a primary care practice. Patients identified with a risk factor for chronic liver disease were invited to a community-based risk stratification pathway for transient elastography readings with both probes. A threshold of ≥8.0 kPa defined elevated liver stiffness.

Results: A total of 477 patients attended the pathway. Of the patients, 21% had no valid measurements with the M probe. There was a significant difference between the probes in the proportion achieving ≥10 valid readings (M versus XL probe: 66.2% versus 90.2%;  ≤ 0.001) and in their reliability (M versus XL probe: 77.4% versus 98.5%;  = 0.028). Unreliable readings with the M probe increased as the body mass index increased. The XL probe re-stratified 5.2% of patients to have a normal reading.

Conclusion: The XL probe on a portable device significantly improves the applicability of transient elastography within a community-based risk stratification pathway.