Clinical application of the Innovance D-dimer assay in the diagnosis of acute pulmonary thromboembolism.

Abstract

Patients with acute pulmonary thromboembolism (APTE) have a high short-term mortality rate. The current study aimed to investigate the use of D-dimer in the diagnosis of APTE in suspected APTE patients. All suspected APTE patients were classified into diagnosis or control groups according to the results of a computed tomography pulmonary angiogram. Mann-Whitney U and Kruskal-Wallis H tests were used to evaluate the association between D-dimer values and APTE. Area under the curve (AUC) values and the Youden Index were used to determine D-dimer cut-off levels for the prediction of APTE. The data of 112 suspected APTE patients (54.8% women; mean age, 70.5 years) were analyzed prospectively. There were no significant differences in age (74.5 vs. 73.5 years, P=0.538) or gender distribution (female ratio 56.5 vs. 53.0%, P=0.847) between the diagnosis and control groups. The incidence of symptoms including dyspnea (67.4 vs. 33.3%; P<0.01), chest distress (47.8 vs. 25.8%; P<0.05) and elevated D-dimer (8.49 vs. 0.97 mg/l; P<0.001) were significantly higher in patients with APTE compared with the control group. D-dimer values >3.32 mg/l fibrinogen equivalent units (FEU) were indicative of APTE and the Youden Index was 0.69. The maximum AUC was 0.87 (95% CI: 0.79-0.92), the sensitivity and specificity were 89.13 and 80.30%, respectively, the positive and negative likelihood ratios were 4.53 and 0.14, respectively, and the positive and negative predictive values were 75.90 and 91.40%, respectively. A D-dimer value <0.60 mg/l FEU was the optimal threshold for excluding APTE diagnosis, with a sensitivity of 100.0% and a specificity of 28.79%. The positive and negative likelihood ratios were 1.40 and 0.00, respectively, and the positive and negative predictive values were 49.50 and 100.00%, respectively. Thus, D-dimer levels, combined with clinical assessment, yield high sensitivity and specificity in diagnosing APTE.