Lisette van Dam

Cost-effectiveness of MRI for diagnosing recurrent ipsilateral DVT 3 35 INTRODUCTION Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a major health care burden. 1 In the Netherlands alone the costs for VTE management in 2015 was approximately 23 million euros for hospital treatment of almost 25,000 VTE patients, and 14.4 million euros for anticoagulants which increased to 38.2 million euros in 2017 because of the introduction of direct oral anticoagulants (DOACs). 2 The yearly total annual health care costs for VTE in the United States were estimated to be 2 to 10 billion dollars for 300,000-600,000 incident cases. 3 These costs were exclusive of costs for anticoagulant-related bleeding complications and thus true VTE costs are even higher. Therefore, an accurate VTE diagnosis to prevent false-positive diagnosis and subsequent mistreatment is crucial both for individual patients and society as a whole. Notably, the diagnostic management of suspected VTE is still complex in certain settings such as suspected recurrent DVT. The safety of using a clinical decision rule (CDR) in combination with D-dimer testing to rule out recurrent DVT is not established 4,5 and seems not as efficient as in patients with a suspected first DVT episode. 5,6 Moreover, ultrasonographic differentiation of acute recurrent ipsilateral DVT from chronic residual thrombi is difficult, with persisting thrombi being present in up to 50% of patients after 1 year despite adequate treatment. 6-8 Magnetic resonance direct thrombus imaging (MRDTI) is a non-invasive magnetic resonance imaging technique that directly visualizes acute thrombi. 9 MRDTI has been shown to accurately distinguish acute recurrent DVT from chronic residual thrombotic abnormalities 10-12 and was proven to be an accurate, simple, feasible and reproducible diagnostic test for ruling out acute recurrent ipsilateral DVT. 13 Importantly, compression ultrasonography (CUS), which currently is the imaging test of choice in suspected recurrent DVT, was found to be associated with an excess of false-positive diagnoses of 19% compared to MRDTI 13 . Furthermore, in contrast to MRDTI, the CUS interpretation may vary greatly among radiologists. 14 As MRDTI is more expensive than CUS the cost aspect should also be taken into account when determining the optimal diagnostic strategy. We set up to perform a 1-year cost-effectiveness analysis of different diagnostic scenarioswith or withoutMRDTI for suspected recurrent ipsilateral DVT, specifically in the Dutch health care setting to better determine the potential role of MRDTI in daily clinical practice.