D-dimer testing and venous thromboembolism: four view points

Follow-up of guidelines and impact on the management of suspected deep vein thrombosis in emergency departments

AIMS

To evaluate the implementation of the European Society of Cardiology (ESC) guidelines concerning the diagnostic management of deep vein thrombosis (DVT) in emergency departments (ED); and to estimate the additional financial cost and the increase in the time spent in the ED if the guidelines are not followed.

PATIENTS AND METHODS

Retrospective, bi-centric study including all patients directly admitted or referred to the ED for a suspected isolated DVT, between April 1, 2019, and July 30, 2019. The diagnostic management was compared to the 2017 ESC's guidelines.

RESULTS

107 patients were included, 13 had DVT (12%) and three had superficial venous thrombosis (3%). A total of 26 patients (24%) had a diagnostic management according to guidelines. In 72 patients (67%), no assessment of clinical probability score was found. Among the 35 patients in whom a clinical probability score was calculated, 5 patients had an unnecessary D-dimer assay and 2 patients had unjustified imaging. The median time spent in the ED was 185minutes when the recommendations were followed, and 250minutes when they were not (P=0.317). The total estimated additional cost was €232.20.

CONCLUSION

The rate of adherence to the guidelines is low, mainly due to the absence of calculation of a clinical probability. This leads, in addition to the risk of diagnostic error, to an increase in the time spent in the EDs and inappropriate use of the technical platform, resulting in additional costs of care.

Qualitative point-of-care D-dimer testing compared with quantitative D-dimer testing in excluding pulmonary embolism in primary care

BACKGROUND

General practitioners can safely exclude pulmonary embolism (PE) by using the Wells PE rule combined with D-dimer testing.

OBJECTIVE

To compare the accuracy of a strategy using the Wells rule combined with either a qualitative point-of-care (POC) D-dimer test performed in primary care or a quantitative laboratory-based D-dimer test.

METHODS

We used data from a prospective cohort study including 598 adults suspected of PE in primary care in the Netherlands. General practitioners scored the Wells rule and carried out a qualitative POC test. All patients were referred to hospital for reference testing. We obtained quantitative D-dimer test results as performed in hospital laboratories. The primary outcome was the prevalence of venous thromboembolism in low-risk patients.

RESULTS

Prevalence of PE was 12.2%. POC D-dimer test results were available in 582 patients (97%). Quantitative test results were available in 401 patients (67%). We imputed results in 197 patients. The quantitative test and POC test missed one (0.4%) and four patients (1.5%), respectively, with a negative strategy (Wells ≤ 4 points and D-dimer test negative) (P = 0.20). The POC test could exclude 23 more patients (4%) (P = 0.05). The sensitivity and specificity of the Wells rule combined with a POC test were 94.5% and 51.0% and, combined with a quantitative test, 98.6% and 47.2%, respectively.

CONCLUSIONS

Combined with the Wells PE rule, both tests are safe to use in excluding PE. The quantitative test seemed to be safer than the POC test, albeit not statistically significant. The specificity of the POC test was higher, resulting in more patients in whom PE could be excluded.

Utilization and yield of chest computed tomographic angiography associated with low positive D-dimer levels

BACKGROUND

It is unclear to what degree broadly applied D-dimer testing combined with a low threshold for imaging with even minimally positive results may be contributing to the utilization of chest computed tomographic angiography (CTA).

STUDY OBJECTIVES

To determine what proportion of chest CTAs for suspected pulmonary embolism (PE) were performed in the setting of minimally elevated D-dimer levels, and to determine the prevalence of PE in those patients when stratified by clinical risk.

METHODS

Retrospective chart review of all patients who had chest CTA for the evaluation of suspected PE during the years 2002-2006 in a suburban community teaching hospital emergency department.

RESULTS

There were 1136 eligible patient visits, of which 353 (31.1%) were found to have D-dimer levels in the low positive range (0.5-0.99 μg/mL). Of these 353 patients, 9 (2.6%; 95% confidence interval [CI] 0.9-4.2%) were diagnosed with PE. There were also 109 patients (9.6%) who had normal D-dimer levels (<0.5 μg/mL). Two of these 109 (1.8%; 95% CI 0-4.2%) were diagnosed with PE. When stratified by the Pulmonary Embolism Rule-out Criteria, 99 of 353 patients with low positive D-dimer levels (28.0%; 95% CI 23.4-32.7%), and 14 of 109 with normal D-dimer levels (12.8%; 95% CI 6.6-19.1%) were classified as low risk, none of whom had PE.

CONCLUSIONS

Nearly one-third of all chest CTAs were done for patients with minimally elevated D-dimer levels, and another 9.6% for patients with normal D-dimer levels with very low yield. Further research to define clinical criteria identifying patients with minimal risk of PE despite low positive D-dimer levels represents an opportunity to improve both patient safety and utilization efficiency of chest CTA.

Diagnostic value of D-dimer in patients with suspected pulmonary embolism: results from a multicentre outcome study

BACKGROUND

D-dimer tests are used in various diagnostic strategies to exclude pulmonary embolism (PE). However, their role as an exclusionary first-line test is still uncertain, mainly because accuracy of the test varies according to the assay and the studied population.

METHODS

The aim of this multicentre study was to evaluate the accuracy of D-dimer testing in patients with suspected PE. Diagnosis of PE was based on pre-test clinical probability (PCP) evaluation and both single-detector spiral CT (CT) and lower limbs compression ultrasonography (CUS). Lung scanning and/or pulmonary angiography was mandatory when CT or CUS was inconclusive and when both CT and CUS were normal in a patient with a high PCP. All patients were followed-up for 3 months, looking for VTE recurrence. D-dimers were collected within 24 h of inclusion and stored in each local hematology unit, to be analyzed at the end of all inclusions; physicians in charge of the patient were blinded to D-dimer results.

RESULTS

Three hundred and fifty two patients were included in 4 centres. Prevalence of PE was 38.6%. PCP was low in 82 (23.3%), intermediate in 176 (50%) and high in 94 (26.7%) patients. Sensitivity of D-dimer was 96.3% (95% CI: 93-99) and negative predictive value reached 94.4% (95% CI: 90-99). Five patients with a confirmed PE had a D-dimer level below 500 ng/ml (two patients with a high PCP). Among 258 patients with low or intermediate PCP, 80 (31%) had a negative D-dimer test result; three of them had a false negative result and the number needed to test was 3.3. Among 94 patients with a high PCP, 9 had a negative D-dimer test result; two of them had a false negative result and the number needed to test was 13.5.

CONCLUSION

These results confirm that rapid assays used in this study can safely exclude PE in first-line testing only in non-high CP patients.