PRedicting OutcomeS in Preterm nEonates With thromboCyTopenia

Main objective: To develop a sequential interventional prediction model to support transfusion decisions by predicting the risk of major bleeding or death with and without giving a platelet transfusion to neonates with severe thrombocytopenia (i.e., platelet count below 50x10\^9/L), conditional on their characteristics present at the moment of prediction. Study design: Multicenter international observational cohort study. Study population: Neonates with a gestational age below 34 weeks and at least one platelet count below 50x10\^9/L, admitted to a neonatal intensive care unit (NICU) between January 1st 2017 and January 1st 2022. Main study endpoint: Major bleeding or mortality during NICU admission Assessments: Only routine care data will be collected. This includes platelet counts and transfusions, cranial (head) ultrasounds and other information on bleeding, and multiple clinical variables. Statistical analyses: Development of a sequential prediction model under interventions using the cloning-censoring-weighting approach with inverse probability weighting. Validation of the model in a separate cohort of preterm neonates with severe thrombocytopenia.