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

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.