Utility of D-dimer in predicting pulmonary embolism in patients with COVID-19 presenting to the emergency department.

Objectives: While our understanding of coronavirus disease 2019 (COVID-19) has evolved, uncertainty remains regarding utility of previously established pulmonary embolism (PE) screening guidelines in patients with COVID-19. Many studies have investigated the efficacy of D-dimer (DD) screenings for patients with COVID-19 admitted to inpatient services, but few have evaluated patients in the emergency department (ED). The purpose of this study was to investigate utility of DD threshold for PE screening in patients with COVID-19 presenting to the ED.

Methods: This was a retrospective, multicenter cohort including patients presenting to three EDs between March 1, 2020 and February 1, 2021 who tested positive for COVID-19 during ED visit or in 60 days prior to presentation and had DD ordered in ED. Patients were grouped by those who underwent computed tomography pulmonary angiogram (CTPA) to evaluate for PE and those who did not, and descriptive statistics were performed. Those who underwent CTPA were further divided into PE-positive and PE-negative groups. The discriminative ability of DD in predicting PE in patients with COVID-19 was analyzed using the receiver operating characteristic (ROC) curve.

Results: A total of 570 patients with COVID-19 were included in the study, of which 107 underwent CTPA to evaluate for PE. History of diabetes, elevated glucose, elevated lactate dehydrogenase, elevated white blood cell count, elevated platelets, elevated respiratory rate, and lower temperature were associated with increased risk for PE. Compared to those without PE, patients with PE were significantly more likely to be hospitalized (100% vs. 82%,  = 0.020) and admitted to the ICU (64% vs. 24%,  = 0.002). Those with PE had a significantly higher median DD value (21,177 ng/mL) compared to PE-negative group (952 ng/mL,  < 0.001). The ROC curve for DD in predicting PE had an area under the curve of 0.91 (95% confidence interval [0.84, 0.98]). In our study population, the optimal DD threshold for predicting PE was 1815 ng/mL (sensitivity 93% and specificity 80%). A conservative threshold of 1089 ng/mL could be used with sensitivity 100% and specificity 58%.

Conclusion: DD is often elevated in patients with COVID-19, regardless of PE. While the classically used DD cutoff is 500 ng/mL, our study demonstrated a threshold of 1089 ng/mL safely predicted PE in patients with COVID-19 .