A Randomized Trial of Diagnostic Strategies after Normal Proximal Vein Ultrasonography for Suspected Deep Venous Thrombosis: d-Dimer Testing Compared with Repeated Ultrasonography

摘要

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. nnObjective: To evaluate and compare the safety of 2 diagnostic strategies for deep venous thrombosis. nnDesign: Randomized, multicenter trial. nnSetting: Four university hospitals. nnPatients: 810 outpatients with suspected deep venous thrombosis and negative results on proximal vein ultrasonography. nnInterventions: 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). nnMeasurements: Symptomatic deep venous thrombosis diagnosed initially and symptomatic venous thromboembolism during 6 months of follow-up. nnResults: 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. nnLimitations: Seventy patients (8.6%) deviated from the diagnostic protocols, and 9 patients (1.1%) had inadequate follow-up. nnConclusion: 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.