Diagnostic accuracy of D-dimer assay in suspected pulmonary embolism patients

Abstract

Pulmonary embolism (PE) is a frequent and potentially severe disease. So objective testing is required to establish or exclude the presence of pulmonary embolism. This study was carried out to evaluate the diagnostic accuracy of D-dimer test in suspected pulmonary embolism patients. This study was carried out on 30 patients with clinical and radiological signs suspicious of PE. All cases were subjected to the following: evaluation of clinical probability by Revised Geneva Score, plain chest X-ray, CT pulmonary angiography (CTPA), electrocardiographic examination, arterial blood gases analysis, calculated alveolar arterial oxygen (PA-aO2) gradient, duplex ultrasonographic, D-dimer assay, and measurement of partial end tidal carbon dioxide (PetCO2). PE confirmed in 22 cases by CTPA, 20 cases of PE (91%) had positive D-dimer and 2 cases (9%) had negative D-dimer test. The sensitivity, specificity and accuracy of D-dimer in diagnosis of PE were (90%, 37.5%, and 26.6%) respectively. The sensitivity of D-dimer in evaluation of PE when clinical probability of PE low or intermediate was (100%), its specificity was (37.5%), its negative predictive value (NPV) was (100%) and its positive predictive value (PPV) was (67.7%), while in high clinical probability its sensitivity was (83.3%), specificity was (100%) and its PPV was (100%). There was statistically significant difference among the negative and positive PE cases as regards the PetCO2 result (P < 0.05). The sensitivity of PetCO2 in diagnosis of PE was (68%) its specificity was (87.5%), NPV was (50%) and its PPV was (93.7%). D-dimer alone cannot exclude or confirm the presence of PE. The combination of D-dimer, PetCO2 ⩽28.5 mmHg and the clinical probability could improve diagnostic accuracy in patients with suspected PE.