A comparison of spiral computed tomography and latex agglutination D-dimer assay in acute pulmonary embolism using pulmonary arteriography as Gold Standard

Abstract number: P1397

Nilsson T., Soderberg M., Lundqvist G., Cederlund K., Larsen F., Rasmussen E., Svane B., Brohult J., Johnsson H.

Karolinska Institutet, Sweden Karolinska Institutet, Sweden

Purpose  

To study the diagnostic accuracy of contrast medium enhanced spiral computed tomography of the pulmonary arteries (s-CTPA) and a latex agglutination D-dimer assay in patients with suspected pulmonary embolism (PE) by using pulmonary arteriography (PA) and clinical follow up as reference method.

Material and method  

A total of 90 hemodynamically stable patients with symptoms of acute pulmonary embolism were prospectively evaluated with s-CTPA and pulmonary arteriography (PA) within 24 h from admission. Plasma D-dimer levels on admittance were analyzed using a rapid latex agglutination D-dimer assay. The outcome of D-dimer concentrations in plasma below 0.25 and 0.5 mg L^-1 were studied.

Results  

All PA and s-CTPA investigations were regarded as of acceptable diagnostic quality in a consensus reading. 33 patients had a positive PA (37%). Three patients had false negative and two patients had false positive s-CTPA findings. s-CTPA had 91% sensitivity, 96% specificity, 94% positive predictive value (PPV) and 95% negative predictive value (NPV). The sensitivity and specificity for D-dimer below 0.5 mg L^-1 were 79% and 88%, respectively. The PPV and NPV were 81% and 87%. If a cut off level of 0.25 mg L^-1 was used the corresponding figures were 91%, 65%, 63% and 92%.

Conclusion  

s-CTPA has a higher sensitivity and specificity than latex agglutination D-dimer. A cut-off level of 0.25 mg L^-1 can be used as screening method, but s-CTPA must be performed to exclude false positive cases.