Determinants of plasma fibrin D-dimer sensitivity for acute pulmonary embolism as defined by pulmonary angiography

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, a nd clinical utility of the D-dimer for the diagnosis of pulmonary embolism, and to describe the effect of D-dimer assay method (enzyme-linked immunoso rbent 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 ope rating characteristics. Design. - Prospective laboratory investigation. Setting. - Community and tertiary care teaching hospital. Patients. - Consecutive patients with suspected acute pulmonary embolism re ferred for pulmonary angiography from April 1993 through March 1996. Measurements. - Baseline characteristics, the duration and intensity of hep arin anticoagulation, the time interval between symptom onset and plasma D- dimer testing, pulmonary angiography, and the D-dimer level on the day of p ulmonary angiography. Results. - Of 105 consenting patients, 33 (31%) had a positive pulmonary an giogram. The D-dimer sensitivity/ negative predictive value for the ELISA, latex agglutination (American Bioproducts Co/Diagnostica Stage and Biopool International), and membrane ELISA were 100%/100%, 94%/94%, 100%/100%, and 97%/96%, respectively, at a discriminate level of 250 mu g/L or less. The c linical 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 dur ation of symptoms. Conclusions. - The sensitivity of the plasma fibrin D-dimer for the diagnos is of pulmonary embolism depends on the assay method, the assay-specific di scriminate level, and the duration of symptoms. At the appropriate discrimi nate level, the plasma D-dimer is a sensitive but nonspecific test for the diagnosis of pulmonary embolism.