Comparison of new rapid methods for D-dimer measurement to exclude deep vein thrombosis in symptomatic outpatients.

Eighty-seven outpatients consecutively admitted to the emergency unit of our hospital with clinically suspected first deep vein thrombosis (DVT) of a leg had D-dimer levels measured by the following recently introduced fast methods: VIDAS (bioMerieux), LPIA (Mitsubishi), Nephelotex (Biopool), Nycocard (Nycomed) and Instant.I.A. (Diagnostica Stago). A latex agglutination test (Minutex, Biopool) was also performed and a classical ELISA (Gold EIA, Agen) used as reference. Venography was performed in all patients, with DVT diagnosed in 42 (37 proximal). All the new methods can be adopted in emergency situations, since they are suited for individual tests, are rapid and the reagents ready to use. All the methods proved to have a good interassay reproducibility. The new D-dimer and latex agglutination tests showed negative (88-96%) and positive (63-81%) predictive values similar to those of ELISA (92% and 71%, respectively), though the still wide confidence intervals suggest larger patient population series be investigated. As regards clinical application, the use of these tests to rule out DVT should be tested in prospective clinical follow-up trials where anticoagulation is withheld in subjects with negative non-invasive reliable vascular tests and normal D-dimer levels.