Enhancement of the haemostatic effect of platelets in the presence of high normal concentrations of von Willebrand factor for critically ill patients needing platelet transfusion-a protocol for the will-plate randomised controlled trial.

Introduction: von Willebrand Factor (vWF) is a key protein mediating platelet adhesion on the surface of damaged endothelia. To the best of our knowledge, no trial exists that investigated the effect of platelet transfusion in combination with the administration of balanced vWF in severe blood loss, despite being widely used in clinical practice. The Basel Will-Plate study will investigate the impact of the timely administration of balanced vWF (1:1 vWF and FVIII) in addition to platelet transfusion on the need for blood and coagulation factor transfusion in patients admitted to the intensive care unit (ICU) who suffer from severe bleeding. The study hypothesis is based on the assumption that adding balanced vWF to platelets will reduce the overall need for transfusion of blood products compared to the transfusion of platelets alone.

Methods And Analysis: The Will-Plate study is an investigator-initiated, single-centre, double-blinded randomised controlled clinical trial in 120 critically ill patients needing platelet transfusion. The primary outcome measure will be the number of fresh frozen plasma (FFP) and red blood cell (RBC) transfusions according to groups. Secondary outcome measures include the number of platelet concentrates transfused within the first 48 h after treatment of study medication, quantity of blood loss in the first 48 h after treatment with the study medication, length of stay in ICU and hospital, number of revision surgeries for haemorrhage control, ICU mortality, hospital mortality, 30-day mortality and 1-year mortality. Patients will be followed after 30 days and 1 year for activities of daily living and mortality assessment. The sample size was calculated to detect a 50% reduction in the number of blood products subsequently transfused within 2 days in patients with Wilate® compared to placebo.

Ethics And Dissemination: This study has been approved by the Ethics Committee of Northwestern and Central Switzerland and will be conducted in compliance with the protocol, the current version of the Declaration of Helsinki, the ICH-GCP or ISO EN 14155 (as far as applicable) and all national legal and regulatory requirements. The study results will be presented at international conferences and published in a peer-reviewed journal.

Trials Registration: ClinicalTrials.gov NCT04555785.

Protocol Version: Clinical Study Protocol Version 2, 01.11.2020. Registered on Sept. 21, 2020.