Comparison of six D-dimer assays for the detection of clinically suspected deep venous thrombosis of the lower extremities.

Deep venous thrombosis is a common disease that may lead to life-threatening embolism of the lung as a common complication. Therefore, early diagnosis followed by sufficient treatment is necessary to decrease mortality of this disease. D-dimer testing is established as a standard to rule out deep venous thrombosis in selected patient groups. However, there is no standardization among D-dimer assays, and a periodical comparison of assay performance in a select patient group is indispensable. We evaluated six commonly used D-dimer assays for their assay performance in an outpatient cohort with clinically suspected deep venous thrombosis. Although area under the curve for these assays did not differ significantly (0.83-0.88), differences in sensitivity (90-100%) and specificity (10-40%) of the assays were detected. Alternative cut-offs were established, and these cut-offs could enhance assay performance in some cases. This points to the fact that the manufacturers should more regularly review studies on the performance of their respective assays to widen the data basis for their recommended cut-offs and increase assay performance.