Can a State-of-the-Art d-Dimer Test Be Used to Determine the Need for CT Imaging in Patients Suspected of Having Pulmonary Embolism?

2002 ◽  
Vol 9 (9) ◽  
pp. 1013-1017 ◽  
Author(s):  
Gerald A.L Irwin ◽  
Jonathan S Luchs ◽  
Virginia Donovan ◽  
Douglas S Katz
CJEM ◽  
2016 ◽  
Vol 18 (S1) ◽  
pp. S117-S117
Author(s):  
K.D. Senior ◽  
K. Burles ◽  
D. Grigat ◽  
D. Wang ◽  
G. Innes ◽  
...  

Introduction: The D-dimer assay is a high sensitivity, low specificity test used to rule out pulmonary embolism (PE) in low risk ED patients. Patients with a positive D-dimer result will likely undergo CT imaging to confirm the diagnosis. Given the time, cost, and radiation exposure associated with CT, and the higher false-positive rate in older patients, an age-adjusted D-dimer threshold may be preferred. Our objective was to evaluate the sensitivity and specificity of an age-adjusted D-dimer and approximate the downstream effect on CT imaging utilization. Methods: This was a retrospective cohort study conducted using administrative data from Calgary emergency departments between July 2013 and January 2015. Eligible patients were individuals aged 50 and older who were undergoing PE workup including D-dimer testing. Outcomes were ascertained using CT imaging reports and by searching the regional administrative database for subsequent diagnosis of PE within 30 days of the index visit. These data were used to calculate the sensitivity, specificity, positive predictive value, and negative predictive value of the D-dimer test using the standard threshold (500 ng/mL) and an age-adjusted threshold (10 ng/mL x patient age as an integer). From this, the potential reduction in CT imaging use and missed PE diagnoses were modeled. Results: Of 6669 patients aged 50 or older who had D-dimer testing for possible PE, 1504 (22.6%) underwent a CT scan, and 217 (14.4% of CT) received a discharge diagnosis of pulmonary embolism, which was confirmed on chart review. When test results were re-interpreted using an age-adjusted threshold, D-dimer specificity increased from 63.9% to 75.4%, while sensitivity decreased from 96.5% to 89.9%. This translates to 888 new true negatives, representing CT scans potentially avoided (a 59% reduction in CT utilization), but with 18 new missed PE diagnoses. Conclusion: The age-adjusted threshold may reduce use of CT imaging among older patients suspected of PE, but at the cost of more missed PE diagnoses.


2008 ◽  
Vol 1 (2) ◽  
pp. 11
Author(s):  
DAMIAN MCNAMARA
Keyword(s):  
D Dimer ◽  

VASA ◽  
2014 ◽  
Vol 43 (6) ◽  
pp. 450-458 ◽  
Author(s):  
Julio Flores ◽  
Ángel García-Avello ◽  
Esther Alonso ◽  
Antonio Ruíz ◽  
Olga Navarrete ◽  
...  

Background: We evaluated the diagnostic efficacy of tissue plasminogen activator (tPA), using an enzyme-linked immunosorbent assay (ELISA) and compared it with an ELISA D-dimer (VIDAS D-dimer) in acute pulmonary embolism (PE). Patients and methods: We studied 127 consecutive outpatients with clinically suspected PE. The diagnosis of PE was based on a clinical probability pretest for PE and a strict protocol of imaging studies. A plasma sample to measure the levels of tPA and D-dimer was obtained at enrollment. Diagnostic accuracy for tPA and D-dimer was determined by the area under the receiver operating characteristic (ROC) curve. Sensitivity, specificity, predictive values, and the diagnostic utility of tPA with a cutoff of 8.5 ng/mL and D-dimer with a cutoff of 500 ng/mL, were calculated for PE diagnosis. Results: PE was confirmed in 41 patients (32 %). Areas under ROC curves were 0.86 for D-dimer and 0.71 for tPA. The sensitivity/negative predictive value for D-dimer using a cutoff of 500 ng/mL, and tPA using a cutoff of 8.5 ng/mL, were 95 % (95 % CI, 88–100 %)/95 % (95 % CI, 88–100 %) and 95 % (95 % CI, 88–100 %)/94 %), respectively. The diagnostic utility to exclude PE was 28.3 % (95 % CI, 21–37 %) for D-dimer and 24.4 % (95 % CI, 17–33 %) for tPA. Conclusions: The tPA with a cutoff of 8.5 ng/mL has a high sensitivity and negative predictive value for exclusion of PE, similar to those observed for the VIDAS D-dimer with a cutoff of 500 ng/mL, although the diagnostic utility was slightly higher for the D-dimer.


1993 ◽  
Vol 70 (03) ◽  
pp. 408-413 ◽  
Author(s):  
Edwin J R van Beek ◽  
Bram van den Ende ◽  
René J Berckmans ◽  
Yvonne T van der Heide ◽  
Dees P M Brandjes ◽  
...  

SummaryTo avoid angiography in patients with clinically suspected pulmonary embolism and non-diagnostic lung scan results, the use of D-dimer has been advocated. We assessed plasma samples of 151 consecutive patients with clinically suspected pulmonary embolism. Lung scan results were: normal (43), high probability (48) and non-diagnostic (60; angiography performed in 43; 12 pulmonary emboli). Reproducibility, cut-off values, specificity, and percentage of patients in whom angiography could be avoided (with sensitivity 100%) were determined for two latex and four ELISA assays.The latex methods (cut-off 500 μg/1) agreed with corresponding ELISA tests in 83% (15% normal latex, abnormal ELISA) and 81% (7% normal latex, abnormal ELISA). ELISA methods showed considerable within- (2–17%) and between-assay Variation (12–26%). Cut-off values were 25 μg/l (Behring), 50 μg/l (Agen), 300 μg/l (Stago) and 550 μg/l (Organon). Specificity was 14–38%; in 4–15% of patients angiography could be avoided.We conclude that latex D-dimer assays appear not useful, whereas ELISA methods may be of limited value in the exclusion of pulmonary embolism.


1994 ◽  
Vol 72 (01) ◽  
pp. 089-091 ◽  
Author(s):  
P de Moerloose ◽  
Ph Minazio ◽  
G Reber ◽  
A Perrier ◽  
H Bounameaux

SummaryD-dimer (DD), when measured by a quantitative enzyme-linked immunosorbent assay (ELISA), is a valuable test to exclude venous thromboembolism (VTE). However, DD ELISA technique is not appropriate for emergency use and the available agglutination latex assays are not sensitive enough to be used as an alternative to rule out the diagnosis of VTE. Latex assays could still be used as screening tests. We tested this hypothesis by comparing DD levels measured by ELISA and latex assays in 334 patients suspected of pulmonary embolism. All but one patient with a positive (DD ≥500 ng/ml) latex assay had DD levels higher than 500 ng/ml with the ELISA assay. Accordingly, ELISA technique could be restricted to patients with a negative result in latex assay. This two-step approach would have spared about 50% of ELISA in our cohort. In conclusion, our data indicate that a latex test can be used as a first diagnostic step to rule out pulmonary embolism provided a negative result is confirmed by ELISA and the performance of the latex assay used has been assessed properly.


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