Abstract
Objectives In patients with suspected venous thromboembolism (VTE), the D-dimer assay is commonly utilized as part of the workup. The assay is primarily used to determine whether to proceed with radiographic imaging. We compared D-dimer levels in patients suspected of having VTE. We hypothesized that higher D-dimer values predict a higher likelihood of subsequent VTE diagnosis. Methods We conducted a secondary analysis of a multinational, prospective observational study of low- to intermediate-risk adult patients presenting to the emergency department with suspicion of VTE. Demographic and clinical data were collected in a structured manner. Advanced imaging including ultrasound, computed tomography (CT) pulmonary angiography, and ventilation/perfusion scanning was obtained at the discretion of the treating physicians. Imaging was evaluated by board-certified radiologists in real time. D-dimer values' bins were evaluated using a logistic regression model. Results We evaluated 1,752 patients for suspected deep vein thrombosis (DVT), with 191 (10.4%) DVT positive. We evaluated 1,834 patients for suspected pulmonary embolism (PE), with 108 (5.9%) PE positive. Higher D-dimer values in both groups were associated with higher likelihood of subsequent VTE diagnosis, with D-dimer values > 3,999 ng/mL in both groups having the highest incidence of VTE. More than 50% of those patients were VTE positive. Conclusions Increasing D-dimer values predict increased likelihood of being found VTE positive in this patient population. Among those in the highest D-dimer category, > 3,999 ng/mL, over half of patients were VTE positive. Further research could determine additional nuance in D-dimer as a tool to work up suspected VTE.
Highlights
D-dimer testing in the workup of patients with potential venous thromboembolism (VTE) is commonplace.[1,2,3,4,5,6,7] When used appropriately, D-dimer testing has demonstrated a reduction in radiographic imaging, decreased emergency department (ED) length of stay, and decreased total health care costs in appropriately risk-stratified groups.[8]
Further research could determine additional nuance in D-dimer as a tool to work up suspected VTE
Some studies have demonstrated an increase in workups and radiographic imaging for VTE with the introduction of the Ddimer assay without an associated increase in diagnosis.[9]
Summary
The D-dimer has been utilized as a dichotomous test When used in this manner, the Ddimer has a specificity at or below 50%.1,10. There have been several studies demonstrating that D-dimer values can be used as continuous variables to predict likelihood of pulmonary embolism (PE) These studies have shown that a patient’s chance of having PE increases with rising D-dimer concentration.[14,15,16] there have not been any studies to date evaluating use of continuous D-dimer values in patients with suspected deep vein thrombosis (DVT). One study found a D-dimer value greater than 3.6 μg/mL increased the likelihood of subsequent DVT diagnosis.[17] To date, there have not been any studies examining the upper value D-dimer concentrations in the risk stratification of patients with suspected DVT
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