Clinical risk assessment model to predict venous thromboembolism risk after immobilization for lower-limb trauma

Banne Nemeth; Delphine Douillet; Saskia le Cessie; Andrea Penaloza; Thomas Moumneh; Pierre-Marie Roy; Suzanne Cannegieter

doi:10.1016/j.eclinm.2020.100270

Clinical risk assessment model to predict venous thromboembolism risk after immobilization for lower-limb trauma

EClinicalMedicine. 2020 Feb 4:20:100270. doi: 10.1016/j.eclinm.2020.100270. eCollection 2020 Mar.

Authors

Banne Nemeth^{1

2}, Delphine Douillet³, Saskia le Cessie^{1

4}, Andrea Penaloza⁵, Thomas Moumneh³, Pierre-Marie Roy³, Suzanne Cannegieter^{1

6}

Affiliations

¹ Department of Clinical Epidemiology, Leiden University Medical Center, The Netherlands.
² Department of Orthopaedic Surgery, Leiden University Medical Center, The Netherlands.
³ Department of Emergency Medicine, Angers University Hospital, MITOVASC Institute, University of Angers, Angers, France.
⁴ Department of Biomedical Data Sciences, Leiden University Medical Center, The Netherlands.
⁵ Department of Emergency Medicine, Cliniques Universitaires Saint Luc, Université Catholique de Louvain, Brussels, Belgium.
⁶ Division of Thrombosis and Haemostasis, Leiden University Medical Center, The Netherlands.

Abstract

Background: Patients with lower-limb trauma requiring immobilization have an increased risk of venous thromboembolism (VTE). While thromboprophylaxis for all patients seems not effective, targeted thromboprophylaxis in high risk patients may be an appropriate alternative. Therefore, we aimed to develop and validate a risk assessment model for VTE risk: the TRiP(cast) score (Thrombosis Risk Prediction following cast immobilization).

Methods: In this prediction model study, for development, data were used from the MEGA study (case-control study into the etiology of VTE) and for validation, data from the POT-CAST trial (randomized trial on the effectiveness of thromboprophylaxis following cast immobilization) were used. Model discrimination was calculated by estimating the Area Under the Curve (AUC). For model calibration, observed and predicted risks were assessed.

Findings: The TRiP(cast) score includes 14 items; one item for trauma severity (or type), one for type of immobilization and 12 items related to patients' characteristics. Validation analyses showed an AUC of 0.74 (95%CI 0.61-0.87) in the complete dataset (n = 1250) and 0.72 (95%CI 0.60-0.84) in the imputed data set (n = 1435). The calibration plot shows the degree of agreement between the observed and predicted risks (intercept 0.0016 and slope 0.933). Using a cut-off score of 7 points in the POT-CAST trial (incidence 1.6%), the sensitivity, specificity, positive and negative predictive values were 76.1%, 51.2%, 2.5%, and 99.2%, respectively.

Interpretation: The TRiP(cast) score provides a helpful tool in daily clinical practice to accurately stratify patients in high versus low-risk categories in order to guide thromboprophylaxis prescribing. To accommodate implementation in clinical practice a mobile phone application has been developed.

Funding: ZonMW VIMP grant:17110200011.

Keywords: Immobilization; Prediction; Risk; Risk assessment model; Trauma; Venous thromboembolism.