Rapid quantitative D‐dimer to exclude pulmonary embolism: a prospective cohort management study

Abstract

EssentialsIt is not known if D-dimer testing alone can safely exclude pulmonary embolism (PE). We studied the safety of using a quantitative latex agglutination D-dimer to exclude PE in 808 patients. 52% of patients with suspected PE had a negative D-dimer test and were followed for 3 months. The negative predictive value of D-dimer testing alone was 99.8%, suggesting it may safely exclude PE.Summary. Background: Strategies are needed to exclude pulmonary embolism (PE) efficiently without the need for imaging tests. Although validated rules for clinical probability assessment can be combined with D-dimer testing to safely exclude PE, the rules can be complicated or partially subjective, which limits their use. Objectives: To determine if PE can be safely excluded in patients with a negative D-dimer without incorporating clinical probability assessment. Patients/Methods: We enrolled consecutive outpatients and inpatients with suspected PE from four tertiary care hospitals. All patients underwent D-dimer testing using the MDA D-dimer test, a quantitative latex agglutination assay. PE was excluded in patients with a D-dimer less than 750 lg FEU L À1 without further testing. Patients with D-dimer levels of 750 lg FEU L À1 or higher underwent standardized imaging tests for PE. All patients in whom PE was excluded had anticoagulant therapy withheld and were followed for 3 months for venous thromboembolism (VTE). Suspected events during follow-up were adjudicated centrally. Results: Eight hundred and eight patients were enrolled, of whom 99 (12%) were diagnosed with VTE at presentation. Four hundred and twenty (52%) patients had a negative D-dimer level at presentation and were not treated with anticoagulants; of these, one had VTE during follow-up. The negative predictive value of D-dimer testing for PE was 99.8% (95% confidence interval, 98.7-99.9%). Conclusions: A negative latex agglutination D-dimer assay is seen in about one-half of patients with suspected PE and reliably excludes PE as a stand-alone test.

Safety of D‐dimer testing as a stand‐alone test for the exclusion of deep vein thrombosis as compared with other strategies

“…The strengths of our study include its prospective outcome design and collection of data, standardized assessment, including the same D‐dimer assay in all patients, and no losses to follow‐up in the group with negative D‐dimer results who did not undergo CUS. Additionally, the DVT prevalence of 19% in our study is comparable to that in other similarly designed diagnostic studies . This relatively high prevalence decreases the likelihood of a low failure rate resulting from a low prevalence, which may arise as a result of the lower diagnostic threshold seen in recent times .…”

“…To our knowledge, only two other prospective outcome studies have evaluated D‐dimer testing as a stand‐alone test for excluding VTE , and, as far as we know, ours is the only recent study to do so for DVT. The previous studies found similar overall negative predictive values of 99.3% and 99.8%, respectively.…”

Age‐adjusted D‐dimer cut‐off leads to more efficient diagnosis of venous thromboembolism in the emergency department: a comparison of four assays

“…This does not accord with the recommended diagnostic algorithm, but nevertheless is not uncommon in clinical practice . It was recently suggested that D‐dimer (< 0.75 mg L −1 FEU) could be used without previous assessment of clinical pre‐test possibility to exclude PE ; however, this could not be verified in a meta‐analysis . It is noteworthy, with respect to the high sensitivities observed in the present cohort of mixed clinical probability, that the false negative results observed in the study were minor thromboses (i.e.…”

Review of D‐dimer testing: Good, Bad, and Ugly

“…A negative D‐dimer result can exclude the diagnosis of VTE without further testing, but only if the sensitivity of the test is high (>98%) . However, high sensitivity comes at the cost of specificity.…”