Role of D-dimer in guiding duration of anticoagulant therapy in the management of first unprovoked proximal lower limb deep venous thrombosis

SummaryThe serial use of non-invasive tests has been shown to be a safe method of managing outpatients who are suspected of having lower limb deep venous thrombosis (DVT). Objective testing has shown that the majority of these outpatients do not have venous thrombosis. A rapid test to exclude DVT in these patients, without the need for expensive and inconvenient serial non-invasive vascular testing, would have practical and economic advantages.Studies measuring the fibrin degradation product D-dimer using enzyme-linked immunoassays (EIA) in patients with veno-graphically proven DVT suggest that it should be possible to exclude this condition by the use of one of the rapid latex bead D-dimer tests.We have examined 190 patients with suspected DVT using both a latex and an EIA D-dimer assay. The latex D-dimer test used in this study was negative in 7 of the 36 proven cases of DVT. This sensitivity of only 80% is not sufficient to allow this type of assay, in its current form, to be used as an exclusion test for DVT. The same plasma samples were tested with an EIA assay. This information was used to mathematically model the effects of selecting a range of D-dimer discriminant cut off points for the diagnosis of DVT. These results indicate that 62% of suspected clinically significant DVT could have this diagnosis excluded, with a 98% sensitivity, if the rapid latex or equivalent D-dimer test could be reformulated to measure less than 185 ng/ml of D-dimer.

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Evaluating the Use of a Negative D-Dimer and Modified Low Wells Score in Excluding above Knee Deep Venous Thrombosis in an Outpatient Population, Assessing Need for Diagnostic Ultrasound

ISRN Radiology ◽

10.1155/2014/519875 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

Maryam Rahiminejad ◽

Anshul Rastogi ◽

Shirish Prabhudesai ◽

David Mcclinton ◽

Peter MacCallum ◽

...

Keyword(s):

Risk Factor ◽

Venous Thrombosis ◽

Deep Venous Thrombosis ◽

Lower Limb ◽

Clinical Risk Factor ◽

Diagnostic Pathway ◽

Clinical Diagnostic ◽

Retrospective Audit ◽

Wells Score ◽

D Dimer

Aims. Colour doppler ultrasonography (CDUS) is widely used in the diagnosis of deep venous thrombosis (DVT); however, the number of scans positive for above knee DVT is low. The present study evaluates the reliability of the D-dimer test combined with a clinical probability score (Wells score) in ruling out an above knee DVT and identifying patients who do not need a CDUS. Materials and Method. This study is a retrospective audit and reaudit of a total of 816 outpatients presenting with suspected lower limb DVT from March 2009 to March 2010 and from September 2011 to February 2012. Following the initial audit, a revised clinical diagnostic pathway was implemented. Results. In our initial audit, seven patients (4.9%) with a negative D-dimer and a low Wells score had a DVT. On review, all seven had a risk factor identified that was not included in the Wells score. No patient with negative D-dimer and low Wells score with no extra clinical risk factor had a DVT on CDUS (negative predictive value 100%). A reaudit confirmed adherence to our revised clinical diagnostic pathway. Conclusions. A negative D-dimer together with a low Wells score and no risk factors effectively excludes a lower limb DVT and an ultrasound is unnecessary in these patients.

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