Evaluation of the new simple and objective clinical decision rule "I-DVT" in patients with clinically suspected acute deep vein thrombosis

Abstract

Introduction: The Wells rule is the recommended first step in the work-up of suspected deep vein thrombosis (DVT). However, it is often incorrectly used leading to an excessive number of diagnostic tests used in daily practice and diagnostic failures. A simpler objective risk stratification tool may improve adherence to the guidelines. We evaluated the diagnostic performance of the I-DVT score, which consists of four easy assessable variables: Immobilization, >3cm Difference in calve circumferences, prior Venous thromboembolism (VTE) and active malignant Tumor.

Methods: We performed an observational study in 617 consecutive patients with suspected DVT. All patients were managed according to the recommended algorithm starting with the Wells rule followed by D-dimer test and/or compression ultrasonography (CUS). The I-DVT score was prospectively calculated at baseline and evaluated post-hoc.

Results: The DVT prevalence was 36%. DVT could be excluded in 13% of patients without CUS by the Wells rule and a normal D-dimer test, with a 3-month VTE incidence of 1.2% (95%CI 0.03-6.5%). Using the I-DVT score, DVT would have been excluded in 9.1% of patients without additional CUS, with a 3-month VTE incidence of 0% (95%CI 0.0-6.4%). The area under the ROC curve (AUC) was 0.70 (95%CI 0.66-0.74) and 0.65 (95%CI 0.61-0.70) for the Wells rule and I-DVT score respectively (difference 0.049, 95%CI -0.01-0.11; p=0.13).

Conclusions: The simple I-DVT score and Wells rule have comparable diagnostic accuracy. It's safety, efficiency and associated potential improvement of guideline adherence in clinical practice has to be further evaluated in a prospective management study.

Keywords: Clinical decision rule; Decision support techniques; Diagnosis; Fibrin fibrinogen degradation products; Venous thrombosis.