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
The purpose of this study was to evaluate whether the determination
of pretest probability using a simple clinical model and the SimpliRED
D-dimer could be used to improve the management of hospitalized patients
with suspected deep-vein thrombosis. Consecutive hospitalized
patients with suspected deep-vein thrombosis, had their pretest probability
determined using a clinical model and had a SimpliRED D-dimer
assay. Patients at low pretest probability underwent a single ultrasound
test. A negative ultrasound excluded the diagnosis of deepvein
thrombosis whereas a positive ultrasound was confirmed by venography.
Patients at moderate pretest probability with a positive ultrasound
were treated for deep-vein thrombosis whereas patients with an initial
negative ultrasound underwent a single follow-up ultrasound one week
later. Patients at high pretest probability with a positive ultrasound were
treated whereas those with negative ultrasound underwent venography.
All patients were followed for three months for the development of venous
thromboembolic complications. Overall, 28% (42/150), and 10%
(5/50), 21% (14/71) and 76% (22/29) of the low, moderate and high
pretest probability patients, respectively, had deep vein thrombosis.
Two of 111 (1.8%; 95% CI = 0.02% to 6.4%) patients considered to
have deep vein thrombosis excluded had events during three-month follow-
up. Overall 13 of 150 (8.7%) required venography and serial testing
was limited to 58 of 150 (38.7%) patients. The negative predictive
value of the SimpliRED D-dimer in patients with low pretest probability
was 96.2%, which is not statistically different from the negative predictive
value of a negative ultrasound result in low pretest probability
patients (97.8%). Management of hospitalized patients with suspected
deep-vein thrombosis based on clinical probability and ultrasound of
the proximal deep veins is safe and feasible.