Clinical usefulness of D-dimer test with semiquantitative latex agglutination method in pulmonary embolism

Abstract

Background: Diagnosing a pulmonary embolism is difficult because its presenting symptoms are nonspecific and there are limitations with all of the objective tests. The D-dimer is known to be a marker of the lysis of intravascular cross-linked fibrin as a result of the activation of the endogenous fibrinolytic pathways, and the D-dimer assay is these an objective method for diagnosing a pulmonary embolism. This study assessed the benefits of the D-dimer test for diagnosing a pulmonary embolism using semiquantitative latex agglutination. Methods: The latex agglutination results of 185 patients were retrospectively reviewed The D-dimer test was performed at the time a pulmonary embolism was suspected Ninety patients(group I) were diagnosis with PE through spiral chest CT or a chest CT angiogram, perfusion/ventilation scans, and/or pulmonary angiogram. Ninety-five patients (group II) were found not to have a pulmonary embolism through the above tests. Results: The male to female ratio and mean age in groups I and II was 37:55, and 57 years old to 50:45 and 52 years old respectively. When the cut off value for a positive D-dimer assay was set to 500 μg, the sensitivity, positive predictive value, negative predictive value and specificity was 86.7%, 61.4%, 79.3%, and 48.4%, respectively. Conclusion: The semiquantitative latex agglutination method in the D-dimer test has a lower sensitivity and negative predictive value than the well known ELISA test particularly for small emboli. Therefore, this test is not a suitable screening test for excluding a pulmonary embolism.