Summary

An optimal approach to the diagnosis of deep vein thrombosis(DVT) in lower limbs in the emergency department is stillunknown. In this prospective cohort study, we aimed to evaluatethe accuracy of the widely available plasma D-dimer test(VIDAS) and establish the usefulness of combining D-dimertesting with a clinical model to reduce the need for serial ultra-sonographiesand improve the diagnostic strategy of DVT.We performed a cohort study in 383 consecutive outpatientsreferred to the emergency department of Hospital La Princesa,with clinical suspicion of DVT. The patients were stratified intothree pre-test probability categories using an explicit clinicalmodel (Wells score), and underwent a quantitative automatedELISA D-dimer assay (VIDAS D-Dimer® bioMérieux). Patientswere managed according to the diagnostic strategy based onclinical probability and compression ultrasonography (CU).Patients for whom DVT was considered a high pre-test probabilitywith negative ultrasonographic findings in the initial CU,returned the following week for repeat ultrasonography. Allpatients with DVT excluded did not receive anticoagulant therapy, and were followed up for three months to monitor thedevelopment of venous thromboembolic complications. DVTwas confirmed in 102 patients (26.6%): 95 in the initial test, fourin the second test, and three who developed venous throm-boemboliccomplications in the three-month follow-up period.The calculated D-dimer cut-off level was 1 µg/ml. One hundredpatients (98%) with DVT had positive D-dimer. D-dimer had asensitivity of 98% and a negative predictive value of 98.6%.Among the high-probability patients with positive D-dimertests and initial negative CU, 9.75% had DVT on repeat CU atone week.The study results suggest that the addition of VIDASD-dimer to this diagnostic algorithm could improve the managementof patients with suspected DVT in daily practice.A diagnostic approach of DVT based on D-dimer (cut-off/ge;1 µg/ml) as the first diagnostic tool for the exclusion of DVT,and the clinical probability model as the tool that identifiesthose patients requiring a second ultrasonography is useful andsuitable for daily medical practice.