title: Evaluation of a new rapid quantitative D-dimer assay in patients with clinically suspected deep vein thrombosis.
abstract: The sensitivity and specificity for deep vein thrombosis (DVT) of a new rapid, quantitative and precise (total imprecision < 10%) D-dimer assay suitable for individual measurements (VIDAS D-DIMER, bio-Mérieux, France) were evaluated in a consecutive series of 103 in- and out-patients submitted to serial compression ultrasonography (C-US) for the clinical suspicion of DVT (n = 66) or of DVT recurrence (n = 37) and symptoms lasting from 1 to 15 days. DVT was found in 22 patients at baseline testing and no patient with an initially negative C-US developed vein incompressibility at follow up. The time elapsed from the onset of symptoms was negatively associated with D-dimer levels both in patients with and in those without DVT. In the entire series of patients, the sensitivity of a positive D-dimer test ( > or = 1.0 microgram/ml) for the presence of DVT was 96% (21/22 patients, 95% confidence interval 75-100%) with a specificity of 75% (64-84%), a negative predictive value of 98% (90-100%), a positive predictive value of 51% (35-67%), and an overall accuracy of 80% (70-87%). A normal D-dimer value (0.22 microgram/ml) was observed in one patient with DVT and symptoms lasting from 15 days. The approach of withholding C-US testing in patients with symptoms lasting from less than 11 days and D-dimer levels below the cut-off value was compared to serial C-US testing alone in a cost-effectiveness analysis subdividing the 66 patients with a first episode according to their clinical pretest probability of DVT. Thrombosis was detected in 6.7% of the patients in the low probability group (n = 15), 16.7% of the patients in the moderate probability group (n = 24), 51.9% of the patients in the high probability group (n = 27) and 8.1% of patients with suspected DVT recurrence. Calculated cost-savings for each DVT diagnosed ranged from 5% in the high pretest probability group to 55% in the low pretest probability group and to 77% in patients with suspected DVT recurrence. The safety of avoiding C-US testing in symptomatic patients with a negative D-dimer test should be evaluated in clinical management studies.
authors.affiliation: Servizio di Coagulazione, Istituto Scientfico H.S. Raffaele, Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: D'Angelo
authors.forename: G
authors.initials: G
authors.lastname: D'Alessandro
authors.forename: L
authors.initials: L
authors.lastname: Tomassini
authors.forename: J L
authors.initials: JL
authors.lastname: Pittet
authors.forename: G
authors.initials: G
authors.lastname: Dupuy
authors.forename: L
authors.initials: L
authors.lastname: Crippa
mesh_terms: D000328:Adult; D000368:Aged; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005453:Fluorescence; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013924:Thrombophlebitis / Q000097:blood* / Q000175:diagnosis / Q000000981:diagnostic imaging; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D