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Ann Intern Med. 2009 Feb 17;150(4):229-35.

Safely ruling out deep venous thrombosis in primary care.

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Academic Medical Center, Department of Vascular Medicine, University of Amsterdam, Amsterdam, the Netherlands.



Up to 90% of patients referred for ultrasonography with suspected deep venous thrombosis (DVT) of the leg do not have the disease.


To evaluate the safety and efficiency of using a clinical decision rule that includes a point-of-care d-dimer assay at initial presentation in primary care to exclude DVT.


A prospective management study.


Approximately 300 primary care practices in 3 regions of the Netherlands (Amsterdam, Maastricht, and Utrecht).


1028 consecutive patients with clinically suspected DVT.


Patients were managed on the basis of the result of the clinical decision rule, which included a d-dimer result. Patients with a score of 3 or less were not referred for ultrasonography and received no anticoagulant treatment; patients with a score of 4 or more were referred for ultrasonography.


The primary outcome was symptomatic, objectively confirmed, venous thromboembolism during 3-month follow-up.


The mean age of the 1028 study patients was 58 years, and 37% of patients were men. A valid score was obtained in 1002 patients (98%). In 500 patients (49%), with a score of 3 or less, 7 developed venous thromboembolism within 3 months (incidence, 1.4% [95% CI, 0.6% to 2.9%]). A total of 502 patients (49%) had a score of 4 or more; 3 did not have ultrasonography. Ultrasonography showed DVT in 125 patients (25%), for an overall prevalence in evaluable patients of 13% (125 of 1002). Of the 374 patients who had normal ultrasonography results, 4 developed venous thromboembolism within 3 months (1.1% [CI, 0.3% to 2.7%]).


The study lacked a randomized design and relied on clinical follow-up to detect missed thrombotic disease.


A diagnostic management strategy in primary care by using a simple clinical decision rule and a point-of-care d-dimer assay reduces the need for referral to secondary care of patients with clinically suspected DVT by almost 50% and is associated with a low risk for subsequent venous thromboembolic events.


The Netherlands Organization for Scientific Research.

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