Diagnostic accuracy of liver stiffness measurement for the diagnosis of veno-occlusive disease/sinusoidal obstruction syndrome after hematopoietic stem cell transplantation (HSCT), the ELASTOVOD STUDY: an investigator-initiated, prospective, multicentre diagnostic clinical trial.

Hepatic Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a severe complication following hematopoietic stem cell transplantation (HSCT), traditionally diagnosed based on clinical criteria. This study aimed to evaluate the diagnostic performance of liver stiffness measurement (LSM) as a non-invasive tool for non invasive diagnosis of VOD/SOS. A multicentre clinical trial was conducted in Italy from April 2018 to December 2021, screening 1089 patients across 25 centers. VOD/SOS diagnosis followed established clinical guidelines, and patients underwent comprehensive clinical, laboratory, and imaging evaluations up to +100 days post-HSCT or until VOD/SOS diagnosis. LSM was measured pre-HSCT and on specific post-transplant days (ClinicalTrials.gov: NCT03426358). The study enrolled 774 adults and 167 children. The +100-day incidence of VOD/SOS HSCT was 5.53 and 5.26 in the overall and allo-HSCT population, higher in children (14.3%) than in adults (3.68%). The 100-day overall survival (OS) probability was 89.5% (overall) and 89.0% (allo-HSCT) while one-yr OS 79% and 78%, respectively, with outcomes varying by VOD/SOS occurrence and severity. LSM significantly differed between VOD/SOS patients and non-affected individuals at all post-HSCT time points, correlating with disease severity. A diagnostic algorithm was proposed, achieving ≥95% sensitivity and specificity, with a 6 kPa rule-out and 25 kPa rule-in cut-off, enhanced by the "three-time pre-HSCT rule." Survivors showed declining LSM over time, while non-survivors did not. Fully recovered patients had lower LSM than non-improvers. LSM also distinguished VOD/SOS from other liver complications within +100 days post-HSCT in both adults and children. In conclusion, LSM is a reliable, non-invasive diagnostic tool for VOD/SOS. LSM contribute to differential diagnosis and to treatment response as well. This study underscores the potential of LSM, combined with multidisciplinary expertise, to guide VOD/SOS diagnosis and management in HSCT patients, improving potentially the clinical outcomes.