A randomized trial of diagnostic strategies after normal proximal vein ultrasonography for suspected deep venous thrombosis: D-dimer testing compared with repeated ultrasonography.
BACKGROUND
With suspected deep venous thrombosis and normal results on proximal vein ultrasonography, a negative d-dimer result may exclude thrombosis and a positive D-dimer result may be an indication for venography.


OBJECTIVE
To evaluate and compare the safety of 2 diagnostic strategies for deep venous thrombosis.


METHODS
Randomized, multicenter trial.


METHODS
Four university hospitals.


METHODS
810 outpatients with suspected deep venous thrombosis and negative results on proximal vein ultrasonography.


METHODS
Erythrocyte agglutination D-dimer testing followed by no further testing if the result was negative and venography if the result was positive (experimental) or ultrasonography repeated after 1 week in all patients (control).


METHODS
Symptomatic deep venous thrombosis diagnosed initially and symptomatic venous thromboembolism during 6 months of follow-up.


RESULTS
Nineteen of 408 patients (4.7%) in the D-dimer group and 3 of 402 patients (0.7%) in the repeated ultrasonography group initially received a diagnosis of deep venous thrombosis (P < 0.001). During follow-up of patients without a diagnosis of deep venous thrombosis on initial testing, 8 patients (2.1% [95% CI, 0.9% to 4.0%]) in the D-dimer group and 5 patients (1.3% [CI, 0.4% to 2.9%]) in the repeated ultrasonography group developed symptomatic venous thromboembolism (difference, 0.8 percentage point [CI, -1.1 to 2.9 percentage points]; P > 0.2). Venous thromboembolism occurred in 1.0% (CI, 0.2% to 2.8%) of those with a negative D-dimer result.


CONCLUSIONS
Seventy patients (8.6%) deviated from the diagnostic protocols, and 9 patients (1.1%) had inadequate follow-up.


CONCLUSIONS
In outpatients with suspected deep venous thrombosis who initially had normal results on ultrasonography of the proximal veins, a strategy based on D-dimer testing followed by no further testing if the result was negative and venography if the result was positive had acceptable safety and did not differ from the safety of a strategy based on withholding anticoagulant therapy and routinely repeating ultrasonography after 1 week.
Kearon
Clive
C
McMaster University and the Henderson Research Centre, Hamilton, Ontario, Canada.
Ginsberg
Jeffrey S
JS
Douketis
James
J
Crowther
Mark A
MA
Turpie
Alexander G
AG
Bates
Shannon M
SM
Lee
Agnes
A
Brill-Edwards
Patrick
P
Finch
Terri
T
Gent
Michael
M
D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005500:Follow-Up Studies; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D018608:Ultrasonography, Doppler; D014680:Veins / Q000000981:diagnostic imaging*; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging
D005338:Fibrin Fibrinogen Degradation Products