title: Decrease in sensitivity of D-dimer for acute venous thromboembolism after starting anticoagulant therapy.
abstract: D-dimer testing is useful for the exclusion of acute venous thromboembolism (VTE). Anticoagulant therapy is expected to reduce D-dimer levels in patients with thrombosis and, consequently, it may not be safe to use D-dimer levels to exclude VTE after anticoagulant therapy has been started. The objectives of this study were to estimate the decrease in D-dimer levels after 24 h of heparin therapy and, applying this estimate to the results of a recent study, to calculate the expected reduction in sensitivity. Using pre-defined criteria, we first performed a literature review to determine whether, and by how much, D-dimer levels decrease within 24 h of starting heparin therapy in patients with acute VTE. Using D-dimer levels that were measured in a prospective study of patients with confirmed deep vein thrombosis and/or pulmonary embolism as baselines, we then determined the change in sensitivity (and specificity) that would result from the fall in D-dimer levels that the literature review suggested would have occurred after 24 h of heparin therapy. On the basis of the literature review, we calculated that mean D-dimer levels decrease by 25%, 24 h after starting heparin therapy in patients with acute VTE. This 25% decrease in D-dimer levels resulted in a decrease in sensitivity from 95.6% (95% confidence interval, 90.0-98.6) to 89.4% (95% confidence interval, 83.7-95.1). There is a decrease in D-dimer levels in patients with acute VTE 24 h after starting heparin therapy that is expected to result in a clinically important drop in sensitivity.
authors.affiliation: Hamilton Civic Hospitals Research Centre, and McMaster University, Hamilton, Ontario, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Couturaud
authors.forename: C
authors.initials: C
authors.lastname: Kearon
authors.forename: S M
authors.initials: SM
authors.lastname: Bates
authors.forename: J S
authors.initials: JS
authors.lastname: Ginsberg
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000494:pharmacology / Q000627:therapeutic use*; D015415:Biomarkers; D005188:False Negative Reactions; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006493:Heparin / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D012680:Sensitivity and Specificity; D013997:Time Factors; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000925:Anticoagulants; D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D006493:Heparin