Value of D-dimer levels for the diagnosis of pulmonary embolism: An analysis of 32 cases with computed tomography pulmonary angiography.

D-dimer levels correlate with the extent of pulmonary embolism (PE) on computed tomography pulmonary angiography (CTPA), but the use of D-dimer alone for screening and diagnosing PE remains controversial. This study compared the utility of plasma D-dimer levels for diagnosing PE with that of CTPA (gold standard). This was a retrospective analysis of 32 consecutive patients with suspected PE at the Affiliated Hospital of Yan'an University between OctoberC 2010 and March 2011. Blood was sampled before thrombolytic therapy was administered. D-dimer levels were measured using an automatic system. CTPA was used to diagnose PE and was performed within 48 h of blood sampling using a Siemens Somatom Sensation 64 computed tomography (CT) scanner. ROC curve analysis was performed to evaluate the diagnostic utility of D-dimer levels, with CTPA as the gold standard. Among the 32 patients, CTPA identified 26 patients with PE and 6 patients without obvious abnormality. Using a threshold value of 1.3 µg/ml for D-dimer level, the diagnosis of PE was achieved with a sensitivity of 96.2%, specificity of 50.0%, positive predictive value of 89.3%, negative predictive value of 75.0% and accuracy of 87.5%. D-dimer levels were significantly higher in patients positive for PE on CTPA than in those negative for PE on CTPA (9.85±7.14 vs. 2.82±2.65 µg/ml, P=0.001). Based on ROC curve analysis, the optimal threshold value for D-dimer level in the diagnosis of PE was 1.9 µg/ml. To conclude, D-dimer could be a simple, fast and inexpensive screening method for excluding a diagnosis of PE.