Heparin therapy for 24 hours in patients with acute VTE is estimated to decrease D-dimer levels by 25%, reducing test sensitivity from 95.6% to 89.4%.
Does 24 hours of heparin therapy decrease the sensitivity of D-dimer testing for excluding acute VTE?
D-dimer testing has a clinically important drop in sensitivity for excluding VTE if performed 24 hours after starting heparin therapy, suggesting it may not be safe to use for exclusion after anticoagulation has begun.
Absolute Event Rate: 89.4% vs 95.6%
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.
Couturaud et al. (Mon,) conducted a other in Acute venous thromboembolism. Heparin therapy vs. Baseline (pre-heparin) was evaluated on Sensitivity of D-dimer testing. Heparin therapy for 24 hours in patients with acute VTE is estimated to decrease D-dimer levels by 25%, reducing test sensitivity from 95.6% to 89.4%.