Application of a Diagnostic Clinical Model for the Management of Hospitalized Patients with Suspected Deep-vein Thrombosis
Philip S. Wells, David R. Anderson, Janis Bormanis, Fred Guy, Michael Mitchell, Lisa Gray, Cathy Clement, K. Susan Robinson, Bernard Lewandowski
From the Departments of Medicine and Radiology, University of Ottawa, Ottawa, Canada, Dalhousie University, Halifax, Canada
Summary The purpose of this study was to evaluate whether the determinationof pretest probability using a simple clinical model and the SimpliREDD-dimer could be used to improve the management of hospitalized patientswith suspected deep-vein thrombosis. Consecutive hospitalizedpatients with suspected deep-vein thrombosis, had their pretest probabilitydetermined using a clinical model and had a SimpliRED D-dimerassay. Patients at low pretest probability underwent a single ultrasoundtest. A negative ultrasound excluded the diagnosis of deepveinthrombosis whereas a positive ultrasound was confirmed by venography.Patients at moderate pretest probability with a positive ultrasoundwere treated for deep-vein thrombosis whereas patients with an initialnegative ultrasound underwent a single follow-up ultrasound one weeklater. Patients at high pretest probability with a positive ultrasound weretreated whereas those with negative ultrasound underwent venography.All patients were followed for three months for the development of venousthromboembolic complications. Overall, 28% (42/150), and 10%(5/50), 21% (14/71) and 76% (22/29) of the low, moderate and highpretest probability patients, respectively, had deep vein thrombosis.Two of 111 (1.8%; 95% CI = 0.02% to 6.4%) patients considered tohave deep vein thrombosis excluded had events during three-month follow-up. Overall 13 of 150 (8.7%) required venography and serial testingwas limited to 58 of 150 (38.7%) patients. The negative predictivevalue of the SimpliRED D-dimer in patients with low pretest probabilitywas 96.2%, which is not statistically different from the negative predictivevalue of a negative ultrasound result in low pretest probabilitypatients (97.8%). Management of hospitalized patients with suspecteddeep-vein thrombosis based on clinical probability and ultrasound ofthe proximal deep veins is safe and feasible.