Rapid ELISA assay for plasma D-dimer in the diagnosis of segmental and subsegmental pulmonary embolism - A comparison with pulmonary angiography

Study objective. To assess the accuracy of a rapid ELISA D-dimer assay for the exclusion of pulmonary embolism (PE) in patients suspected of PE, using pulmonary angiography alone as reference method rather than a diagnostic s trategy including lung scintigraphy and leg vein ultrasonography. Methods: In 342 patients who were examined by pulmonary angiography to diagnose or e xclude PE, the accuracy of the quantitative rapid VIDAS D-dimer test for th e exclusion of PE was evaluated retrospectively. D-dimer levels were assaye d in frozen samples collected during the diagnostic work-up at the time of pulmonary angiography while on treatment with unfractionated heparin for 1- 2 days. Results: Mean plasma D-dimer concentrations were increased in patie nts with angiographic evidence of PE (P <0.0001). The sensitivity of D-dime r for segmental PE was 98%, its accuracy in excluding segmental PE was 99%, higher than the respective figures for subsegmental PE (76% and 94%; P <0. 01, both). For both forms of PE combined the sensitivity was 90% and the ne gative predictive value 94%. Discussion: The sensitivity and negative predi ctive values reported here, are low compared with previous studies using th e same rapid ELISA D-dimer assay. This probably reflects an overlooking of mild cases of subsegmental PE in previous studies, although a reduction of D-dimer levels by the heparin pretreatment may have contributed to part of the discrepancy. Prospective studies are needed to clarify this issue.