Model Predicts Risk of Blood Clots in Patients With Cast on Leg Interview with:
Banne Nemeth, MD and Suzanne C. Cannegieter MD PhD
Leiden University Medical Center
The Einthoven Laboratory for Experimental Vascular Medicine
Clinical Department of Epidemiology and Orthopedic Surgery

Medical Research: What is the background for this study? What are the main findings?

Dr. Nemeth: Clinicians cannot currently accurately predict who will develop venous thrombosis, but it would be very helpful to be able to identify individuals at high risk for venous thrombosis because the condition can be prevented by giving anticoagulants before a clot forms (thromboprophylaxis). The ability to predict venous thrombosis would be particularly useful in patients who have had a lower limb immobilized in a cast after, for example, breaking a bone. These patients have an increased risk of venous thrombosis compared to patients without cast immobilization.

We developed and validated a prediction model to identify patients with plaster cast of the lower extremity who are at high risk to develop venous thrombosis. A clinical risk score named, L-TRIP(cast) score (Leiden Thrombosis Risk Prediction for patients with cast immobilization score), was developed containing 14 clinical risk factors such as age, sex, BMI, use of oral contraceptives and location of plaster cast. Patients that score 9 points or higher are classified as being at high risk for venous thrombosis. Clinicians may decide to prescribe thromboprophylaxis therapy for these patients.

Medical Research: What should clinicians and patients take away from your report?

Dr. Nemeth: The results show that information on environmental risk factors, coagulation factors, and genetic determinants in patients with plaster casts leads to high accuracy in the prediction of venous thrombosis risk. In daily practice, the L-TRiP(cast) score may be used to identify patients (with lower extremity plaster cast) at high risk for venous thrombosis.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Nemeth: Our study may provide guidance for thromboprophylaxis therapy in patients with lower extremity plaster cast. Although our model was validated in two independent case-control studies, the L-TRiP(cast) score needs to be tested in longitudinal patient data to estimate an individual’s risk for the development of venous thrombosis.


Thrombosis Risk after Cast Immobilization of the Lower Extremity: Derivation and Validation of a Clinical Prediction Score, L-TRiP(cast), in Three Population-Based Case–Control Studies

Banne Nemeth, Raymond A. van Adrichem, Astrid van Hylckama Vlieg, Paolo Bucciarelli, Ida Martinelli, Trevor Baglin, Frits R. Rosendaal, Saskia le Cessie, Suzanne C. Cannegieter

Published: November 10, 2015 DOI: 10.1371/journal.pmed.1001899

Banne Nemeth, MD and Suzanne C. Cannegieter MD PhD (2015). Model Predicts Risk of Blood Clots in Patients With Cast on Leg