Determinants of Plasma Fibrin D-Dimer Sensitivity for Acute Pulmonary Embolism as Defined by Pulmonary Angiography

Abstract

Abstract Background.—The reported operating characteristics of the plasma fibrin D-dimer level for the diagnosis of acute pulmonary embolism vary widely. Objective.—To determine the sensitivity, specificity, predictive value, and clinical utility of the D-dimer for the diagnosis of pulmonary embolism, and to describe the effect of D-dimer assay method (enzyme-linked immunosorbent assay [ELISA], latex agglutination, membrane ELISA) and discriminate level, patient location at onset, comorbid disease, duration and intensity of concurrent heparin administration, and duration of symptoms on these operating characteristics. Design.—Prospective laboratory investigation. Setting.—Community and tertiary care teaching hospital. Patients.—Consecutive patients with suspected acute pulmonary embolism referred for pulmonary angiography from April 1993 through March 1996. Measurements.—Baseline characteristics, the duration and intensity of heparin anticoagulation, the time interval between symptom onset and plasma D-dimer testing, pulmonary angiography, and the D-dimer level on the day of pulmonary angiography. Results.—Of 105 consenting patients, 33 (31%) had a positive pulmonary angiogram. The D-dimer sensitivity/negative predictive value for the ELISA, latex agglutination (American Bioproducts Co/Diagnostica Stago and Biopool International), and membrane ELISA were 100%/100%, 94%/94%, 100%/100%, and 97%/96%, respectively, at a discriminate level of 250 μg/L or less. The clinical utility, defined as the prevalence of a negative test, ranged from 17% to 33%. D-dimer sensitivity was unaffected by patient location at onset, comorbid disease, or heparin therapy but was inversely related to the duration of symptoms. Conclusions.—The sensitivity of the plasma fibrin D-dimer for the diagnosis of pulmonary embolism depends on the assay method, the assay-specific discriminate level, and the duration of symptoms. At the appropriate discriminate level, the plasma D-dimer is a sensitive but nonspecific test for the diagnosis of pulmonary embolism.