Lisette van Dam

Wells rule and D-dimer test in recurrent ipsilateral DVT 4 59 INTRODUCTION The diagnosis of suspected recurrent deep vein thrombosis (DVT) can be challenging, since there are critical limitations to current diagnostic techniques. 1-3 Diagnostic algorithms incorporating the combination of a clinical decision rule (CDR) and D-dimer tests prior to imaging tests have proved to be useful and safe in a first episode of suspected DVT of the leg. However, the diagnostic performance of these algorithms has not been evaluated in large cohorts of patients with suspected recurrent DVT. 1,2,4 Additionally, due to chronic thrombosis persisting in up to 50% of patients despite adequate anticoagulant treatment, conventional diagnostic imaging tests such as compression ultrasound (CUS) and computed tomography venography are often non-diagnostic in the setting of suspected recurrent ipsilateral DVT. As a result, recurrent DVT cannot be excluded in up to 30% of patients. 2,5,6 Magnetic resonance direct thrombus imaging (MRDTI), a non-contrast-enhanced magnetic resonance imaging (MRI) technique, has been shown to accurately distinguish acute recurrent DVT from chronic residual thrombosis. 7-10 In a recent prospective outcome study (the Theia study), MRDTI was proven to be an accurate, simple, feasible and reproducible diagnostic test for ruling out acute recurrent ipsilateral DVT. 11 Considering both the limited availability and associated costs of MRI and the poor performance of CUS in suspected recurrent ipsilateral DVT, a safe and efficient diagnostic algorithm to reduce the need of diagnostic imaging is an unmet clinical need. We therefore set out to evaluate the diagnostic accuracy of the combination of the Wells rule for DVT and D-dimer measurement for suspected recurrent ipsilateral DVT. METHODS Study population In this analysis, we report on a predefined secondary endpoint of the Theia study (NCT02262052). The full details of the study design and results have been published previously. 11 In summary, 305 consecutive adult patients with suspected recurrent ipsilateral DVTweremanaged according to the Theia study algorithmwithMRDTI as standalone test to guide therapeutic management ( Figure 1 ). The main exclusion