Test Helps to Exclude Diagnosis of Pulmonary Embolism
Plasma fibrin D-dimer latex immunoassay highly sensitive but has low specificity for positive diagnosis
TUESDAY, May 8 (HealthDay News) -- Using a quantitative plasma fibrin D-dimer latex immunoassay can help to effectively exclude a diagnosis of acute pulmonary embolism in some patients, researchers report in the May issue of the Mayo Clinic Proceedings.
David A. Froehling, M.D., of the Mayo Clinic in Rochester, Minn., and colleagues conducted a study of 1,355 computed tomographic angiographies, including 208 that were positive for acute pulmonary embolism. In this sub-group, median D-dimer levels were 1,425 ng/mL, compared to a median 500 ng/mL for those without acute pulmonary embolism.
By using a discriminant value of 300 ng/mL, the test yielded a sensitivity of 0.94 but a specificity of only 0.27. The negative prediction value was 0.96. This means that although the test alone was insufficient to exclude acute pulmonary embolism, it was of more value than the semiquantitative latex agglutination assay and produced a result similar to the rapid enzyme-linked immunosorbent assay.
"On the basis of these results, we believe that a negative quantitative D-dimer latex immunoassay result and a low pretest probability of thromboembolism together are sufficient to exclude acute pulmonary embolism. Unless specific contraindications exist, patients with a high pretest probability of acute pulmonary embolism should undergo computed tomography angiography directly," the authors conclude.