Venous Thromboembolism Risk in Critically Ill Patients: Development and Validation of a Risk Prediction Model

Introduction: Venous thromboembolism (VTE), including both deep vein thrombosis and pulmonary embolism, is a frequent cause of morbidity and mortality. The population of critically ill patients is a heterogeneous group of patients with an overall high average risk of developing VTE. No prognostic model has been developed for estimation of this risk specifically in critically ill patients. The aim is to construct and validate a risk assessment model for predicting the risk of in-hospital VTE in critically ill patients.

Methods: In the first phase of the study we will create a prognostic model based on a derivation cohort of critically ill patients who were acutely admitted to the intensive care unit. A point-based clinical prediction model will be created using backward stepwise regression analysis from a selection of predefined candidate predictors. Model performance, discrimination and calibration will be evaluated, and the model will be internally validated by bootstrapping. In the second phase of the study, external validation will be performed in an independent cohort, and additionally model performance will be compared with performance of existing VTE risk prediction models derived from, and applied to, general medical patients.

Dissemination: This protocol will be published online. The results will be reported according to the Transparent Reporting of multivariate prediction models for Individual Prognosis Or Diagnosis (TRIPOD) statement, and submitted to a peer-reviewed journal for publication.