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We performed a study in 403 prospectively included patients with suspected pulmonary embolism to compare the accuracy of a combination of the SimpliRED D-dimer assay and an intuitive clinical probability estimate with either one alone. Based on a conjoint diagnostic refer, ence standard, including ventilation-perfusion lung scintigraphy and pulmonary angiography, the prevalence 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 combination of the two tests. These figures were more favorable than for either 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 use of the SimpliRED test and the clinical probability estimate attains a higher sensitivity than either test alone. However, there remains a risk of false negatives and the exclusion efficiency is limited.

We prospectively evaluated the diagnostic performance of a new soluble fibrin assay in 303 consecutive patients with suspected pulmonary embolism and examined potentially useful cut-off levels at which this disease can be safely excluded. In addition, the diagnostic accuracy was calculated in the subgroups of in- and outpatients. The ROC curve of the assay in the total study cohort had an area under the curve of 0.69. The cut-off level associated with a sensitivity and negative predictive value of 100% was 20 ng/ml, but the specificity was only 4%. The cut-off level with a sensitivity of 90% was 30 ng/ml, which corresponded with a specificity and negative predictive value of 27% and 86%. respectively. The diagnostic performance was comparable in the subgroups of in- and outpatients. We conclude that the soluble fibrin assay has a low diagnostic accuracy and seems unsuitable as a screening test for the exclusion of pulmonary embolism.

We prospectively evaluated the diagnostic accuracy of the Fibrinostika FbDP assay in 304 consecutive patients with suspected pulmonary embolism and examined potentially useful cut-off points at which the disease can be excluded. The prevalence of pulmonary embolism was 31%. The assay generated an area under the Receiver Operating Characteristic curve of 0.79 (95% CI 0.73-0.84). A cut-off point of 0.05 microg/ml yielded a sensitivity, specificity, negative predictive value and an exclusion efficiency of 100% (95% CI 96-100), 5% (95% CI 2-9), 100% (95% CI 69-100) and 3% (95% CI 2-6), respectively. A clinically useful cut-off point seems to be 0.11 microg/ml which corresponded with a sensitivity, specificity, negative predictive value and an exclusion efficiency of 96% (95% CI 90-99), 27% (95% CI 24-28), 93% (95% CI 84-98) and 20% (95% CI 16-25), respectively. We conclude that the assay has potential clinical utility for the exclusion of pulmonary embolism, but it cannot be used as a sole test.

Recent studies have suggested that both the subjective judgement of a physician and standardized clinical models can be helpful in the estimation of the probability of the disease in patients with suspected pulmonary embolism (PE). We performed a multi-center study in consecutive in- and outpatients with suspected PE to compare the potential diagnostic utility of these methods. Of the 517 study patients, 160 (31%) were classified as having PE. Of these patients, 14% had a low probability as estimated by the treating physician, while 25 to 36% were categorized as having a low clinical probability with the use of two previously described clinical models. The objectively confirmed prevalence of PE in these three low probability categories was 19%, 28% and 28%, respectively. The three methods yielded comparable predictive values for PE in the other probability categories. We conclude that a physician's clinical judgement alone and two standardized clinical models, although comparable, perform disappointingly in categorizing the pre-test probability in patients with suspected PE.