Evidence for Safe Exclusion of Deep Vein Thrombosis (DVT) by a Rapid ELISA D-Dimeer Test at Cut-Off Levels of 500 and 1000 Ng/Ml in 1046 Consecutive Outpatients with Suspected DVT.

Introduction.A normal compression ultrasonography (CUS) safely excludes proximal deep vein thrombosis (DVT) with a negative predictive value of 97% indicating the need to repeat CUS testing within one week. In 3 studies, the rapid ELISA D-dimer assay at a cut-off of 500 ng/ml did have a sensitivity of 100% for the exclusion of venographically documented distal and proximal DVT irrespective of clinical score. To test this hypothesis we performed a large prospective study in outpatients with suspected DVT.

Methods. CUS and a rapid ELISA D-Dimer test (VIDAS, BioMérieux L’Etoile, France) were performed in patients with suspected DVT. A negative CUS with a D-Dimer result of <500 ng/ml exclude DVT, and with a D-Dimer result of >500 ng/ml was followed by a second CUS within one week.

Results. The prevalence of DVT 1046 consecutive out patients with suspected DVT was 23,4%. The first CUS was positive in 228 with a rapid ELISA D-Dimer of >500 ng/ml in 227 and of <500 ng/ml in one case, indicating a sensitivity of 99,6% irrespective of clinical score. The first CUS was negative in 818. The rapid ELISA D-dimer test Was <500 ng/ml in 297 of which 296 had a negative first CUS indicating a negative predictive value of 99.7% at a specificity of 37% irrespective of the clinicl score. The negative predictive value of a negative CUS plus a rapid ELISA D-Dimer result of less than 1000 ng/ml is 99.5% at a specificity of 67,9% irrespective of clinical score. The prevalence of DVT in patients with negative first CUS and a ELISA D-Dimer of >1000 ng/ml was 5.6% as documented by CUS repeat within on week.

Conclusion.A normal rapid ELISA D-dimer test, <500 ng/ml, in outpatients with suspected DVT safely excludes DVT irrespective of clinical score. After a negative rapid ELISA result (<500 ng/ml), CUS is still indicated for safety reasons in patients with suspected DVT and persistent symptoms in search for an alternative diagnosis, or for a rare case of DVT. A negative CUS plus and ELISA D-Dimer result of <1000 ng/ml safely exclude DVT without the need to repeat CUS in 2/3 of patients with a negative first CUS.