Threshold for Platelets (T4P) clinical trial

The Threshold for Platelets study: a prospective randomised trial to define the platelet count below which critically ill patients should receive a platelet transfusion prior to an invasive procedure

Background

Platelets are a type of blood cell that help form blood clots and stop bleeding. Platelet transfusions are given when the number of platelets in the blood (the platelet count) falls below a critical level (the transfusion threshold). Platelet transfusions are commonly given to critically ill patients as these patients often have fewer platelets in their blood than healthy people. A common reason to give a platelet transfusion to a critically ill patient with low platelet levels is to reduce the risk of bleeding before undergoing an invasive procedure.

However, platelet transfusions may have risks, such as an allergic reaction, and may not work as well in critically ill patients. We do not know to what level the platelet count should fall (the best transfusion threshold) before the benefits of giving platelet transfusions outweigh the risks. Given this uncertainty, a wide range of transfusion thresholds are currently used in intensive care units (ICUs) around the world to decide when a platelet transfusion should be given before undergoing an invasive procedure.

The study

This study is a large international clinical trial to find out the best transfusion threshold below which a platelet transfusion should be given to patients who need an invasive procedure in ICU. The study will include 2,550 patients worldwide including 500 patients from Australia. Patients will be randomly allocated (by chance) to one of five platelet transfusion thresholds. If a participating patient’s platelet count drops below their allocated threshold, they will be given a platelet transfusion before their procedure. We will follow up all patients at 90 days and one year. We will work out the best transfusion threshold by comparing the number of patients alive in each group at 90 days.

This study has been registered with the ISRCTN registry with registration number ISRCTN79371664.