Adjusting D-dimer cutoffs: Brief literature summary and issues in clinical use

D-dimer Testing in Pulmonary Embolism with a Focus on Potential Pitfalls: A Narrative Review

D-dimer is a multifaceted biomarker of concomitant activation of coagulation and fibrinolysis, which is routinely used for ruling out pulmonary embolism (PE) and/or deep vein thrombosis (DVT) combined with a clinical pretest probability assessment. The intended use of the tests depends largely on the assay used, and local guidance should be applied. D-dimer testing may suffer from diagnostic errors occurring throughout the pre-analytical, analytical, and post-analytical phases of the testing process. This review aims to provide an overview of D-dimer testing and its value in diagnosing PE and discusses the variables that may impact the quality of its laboratory assessment.

Performance of C-Reactive Protein, Procalcitonin, TAT Complex, and Factor VIII in Addition to D-Dimer in the Exclusion of Venous Thromboembolism in Primary Care Patients

BACKGROUND

In primary care, D-dimer-combined with a clinical assessment-is recommended for ruling-out venous thromboembolism (VTE). However, D-dimer testing frequently yields false-positive results, notably in the elderly, and the search for novel biomarkers thus continues. We assessed the added diagnostic value of 4 promising laboratory tests.

METHODS

Plasma samples from 256 primary care patients suspected of VTE were collected. We explored added value (beyond D-dimer) of C-reactive protein (CRP), procalcitonin (PCT), thrombin-antithrombin III complex (TAT-c), and factor VIII (FVIII). Diagnostic performance of these biomarkers was assessed univariably and by estimating their area under the receiver operating curve (AUC). Added diagnostic potential beyond D-dimer testing was assessed using multivariable logistic regression.

RESULTS

Plasma samples of 237 VTE-suspected patients were available for analysis-36 patients (25%) confirmed deep vein thrombosis, 11 patients (12%) pulmonary embolism. Apart from D-dimer, only CRP, and FVIII levels appeared to be higher in patients with VTE compared to patients without VTE. The AUCs for these 3 markers were 0.76 (95% CI: 0.69-0.84) and 0.75 (95% CI: 0.68-0.83), respectively, whereas the AUC for D-dimer was 0.90 (95% CI: 0.86-0.94). Combining these biomarkers in a multivariable logistic model with D-dimer did not improve these AUCs meaningfully.

CONCLUSIONS

In our dataset, we were unable to demonstrate any added diagnostic performance beyond D-dimer testing of novel biomarkers in patients suspected of VTE in primary care. As such, D-dimer testing appears to remain the best choice in the exclusion of clinically suspected VTE in this setting.

TRIAL REGISTRATION

Netherlands Trial Register NL5974. (METC protocol number: 16-356/M; NL56475.041.16.).

Pulmonary Embolism at CT Pulmonary Angiography in Patients with COVID-19

PURPOSE

To evaluate pulmonary embolism (PE) prevalence at CT pulmonary angiography in patients testing positive for coronavirus disease 2019 (COVID-19) and factors associated with PE severity.

MATERIALS AND METHODS

A retrospective, single-center study evaluated 62 patients who tested positive for COVID-19 who underwent CT pulmonary angiography between March 13 and April 5, 2020. Another 62-patient cohort who underwent CT pulmonary angiography before the first reported local COVID-19 case was retrospectively selected. The relative rate of CT pulmonary angiography positivity was recorded. For the COVID-19 positive cohort, comorbidities, laboratory values, clinical outcome, and venous thrombosis of the patients were recorded. Two thoracic radiologists assessed embolic severity using the Mastora system and evaluated right heart strain. Factors associated with PE and arterial obstruction severity were evaluated by using statistical analysis. A P value < .05 was considered significant.

RESULTS

Of the patients testing positive for COVID-19, 37.1% had PE, higher than 14.5% of pre-COVID-19 patients (P = .007). d-dimer levels closest to CT pulmonary angiography date correlated with the Mastora obstruction score. Receiver operating characteristic analysis identified optimal sensitivity (95%) and specificity (71%) for PE diagnosis at 1394 ng/mL d-dimer units. The mean d-dimer level was 1774 ng/mL and 6432 ng/mL d-dimer units in CT pulmonary angiography-negative and CT pulmonary angiography-positive subgroups, respectively (P < .001). One additional patient with negative results at CT pulmonary angiography had deep venous thrombosis, thus resulting in 38.7% with PE or deep venous thrombosis, despite 40% receiving prophylactic anticoagulation. Other factors did not demonstrate significant PE association.

CONCLUSION

A total of 37.1% of COVID-19 patients underwent CT pulmonary angiographic examinations diagnosing PE. PE can be a cause of decompensation in patients testing positive for COVID-19, and d-dimer can be used to stratify patients in terms of PE risk and severity.Supplemental material is available for this article.© RSNA, 2020.

D-dimer: Preanalytical, analytical, postanalytical variables, and clinical applications

D-dimer is a soluble fibrin degradation product deriving from the plasmin-mediated degradation of cross-linked fibrin. D-dimer can hence be considered a biomarker of activation of coagulation and fibrinolysis, and it is routinely used for ruling out venous thromboembolism (VTE). D-dimer is increasingly used to assess the risk of VTE recurrence and to help define the optimal duration of anticoagulation treatment in patients with VTE, for diagnosing disseminated intravascular coagulation, and for screening medical patients at increased risk of VTE. This review is aimed at (1) revising the definition of D-dimer; (2) discussing preanalytical variables affecting the measurement of D-dimer; (3) reviewing and comparing assay performance and some postanalytical variables (e.g. different units and age-adjusted cutoffs); and (4) discussing the use of D-dimer measurement across different clinical settings.

Comorbidity burden conditions the prognostic performance of D-dimer in elderly patients with acute pulmonary embolism

INTRODUCTION

The prognostic accuracy of D-dimer for risk assessment in acute Pulmonary Embolism (APE) patients may be hampered by comorbidities. We investigated the impact of comorbidity burden (CB) by using the Charlson Comorbidity Index (CCI), on the prognostic ability of D-dimer to predict 30 and 90-day mortality in hemodynamically stable elderly patients with APE.

METHODS

All patients aged >65 years with normotensive APE, consecutively evaluated in the Emergency Department since 2010 through 2014 were included in this retrospective cohort study. Area under the curve (AUC) and ½ Net Reclassification Improvement (NRI) were calculated.

RESULTS

Study population: 162 patients, median age: 79.2 years. The optimal cut-off value of CCI score for predicting mortality was ≤1 (Low CB) and >1 (High CB), AUC = 0.786. Higher levels of D-dimer were associated with an increased risk death at 30 (HR = 1.039, 95%CI:1.000-1.080, p = 0.049) and 90 days (HR = 1.039, 95%CI:1.009-1.070, p = 0.012). When added to simplified Pulmonary Embolism Severity Index (sPESI) score, D-dimer increased significantly the AUC for predicting 30-day mortality in Low CB (AUC = 0.778, 95%CI:0.620-0.937, ½NRI = 0.535, p = 0.015), but not in High CB patients (AUC = 0.634, 95%CI:0.460-0.807, ½ NRI = 0.248, p = 0.294). Similarly, for 90-day mortality D-dimer increased significantly the AUC in Low CB (AUC = 0.786, 95%CI:0.643-0.929, ½NRI = 0.424, p-value = 0.025), but not in High CB patients (AUC = 0.659, 95%CI:0.541-0.778, ½NRI = 0.354, p-value = 0.165).

CONCLUSION

In elderly patients with normotensive APE, comorbidities condition the prognostic performance of D-dimer, which was found to be a better predictor of death in subjects with low CB. These results support multimarker strategies for risk assessment in this population.