P95 Elevated D-dimers in COVID-19 patients predict PE but caution is needed with higher thresholds

Introduction and ObjectivesCOVID-19 is associated with a pro-inflammatory, hypercoagulable state, increasing the likelihood of developing pulmonary embolism (PE). Higher D-dimer levels have been noted in COVID-19 patients compared to the general population, which may lead to over-investigation by computed tomography pulmonary angiography (CTPA) if traditional thresholds (positive ≥0.5mg/L) are used. We aimed to investigate whether a higher D-dimer threshold could be used.MethodsA retrospective observational study was performed at Barking Havering and Redbridge University Hospitals NHS Trust from April 2020 - March 2021. The study included a cohort of confirmed/suspected cases of COVID-19 requiring hospital admission. D-dimer level on admission, CTPA outcome and requirement for intensive care unit (ICU) admission were analysed to assess D-dimer as a predictor of PE and clinical outcome in COVID-19.ResultsIn 404 patients included, mean D-dimer was 3.03mg/L. 186 (46%) underwent CTPA, 32 (17%) of which detected PE. In those with PE, mean D-dimer was (8.62mg/L), significantly higher than those without PE (2.55mg/L) (P = <0.0001). Patients admitted to ICU had a significantly higher D-dimer (4.35mg/L) than those who were not (2.69mg/L) (P = 0.049). Applying the traditional threshold of 0.5mg/L resulted in a sensitivity of 97% and specificity of 10% for detecting PE. Using higher thresholds of 1.0mg/L and 2.0ml/L resulted in sensitivity of 87% and 71%, and specificity of 37% and 69%, respectively.ConclusionsOur data strongly suggests that higher D-dimer levels are associated with disease severity e.g. complication with PE and requirement for ICU admission. Caution is needed as higher thresholds of 2.0ml/L or greater, as suggested in previous studies,1 would have resulted in an unacceptably low sensitivity in this cohort. Our study highlights the need for further work evaluating use of adjusted D-dimer thresholds in patients with acute COVID-19 to aid decision making and help balance the risks of radiation associated with CTPA and consequences associated with missed diagnosis of PE.ReferenceVentura-Diaz S, et al. A higher D-dimer threshold for predicting pulmonary embolism in patients with COVID-19: a retrospective study. Emerg Radiol. 2020;27(6):679-689. doi:10.1007/s10140-020-01859-1