Diagnostic accuracy of triage tests to exclude pulmonary embolism

We performed a study in 403 prospectively included patients with suspected pulmonary embolism to compare the accuracy of a combination of the SimpliRE D D-dimer assay and an intuitive clinical probability estimate with either one alone. Based on a conjoint diagnostic reference standard, including ven tilation-perfusion lung scintigraphy and pulmonary angiography. the prevale nce of pulmonary embolism was 31%. We demonstrated a high sensitivity (98%, 95% CI 95-100) and negative predictive value (94%, 95% CI 79-99) for the c ombination of the two tests. These figures were more favorable than for eit her test alone. The specificity of the combination was lower (11%. 95% CI 9 -12) and consequently the proportion of patients in whom further diagnostic tests would have been avoided was only 8%. We conclude that the combined u se of the SimpliRED test and the clinical probability estimate at rains a h igher sensitivity than either test alone. However. there remains a risk of false negatives: and the exclusion efficiency is limited.