A 10-fold and greater increase in D-dimer at admission in COVID-19 patients is highly predictive of pulmonary embolism in a retrospective cohort study

BACKGROUND: COVID-19 patients present with both elevated D-dimer and a higher incidence of pulmonary embolism (PE). This single-centre retrospective observational study investigated the prevalence of early PE in COVID-19 patients and its relation to D-dimer at presentation. METHODS: The study included 1038 COVID-19-positive patients, with 1222 emergency department (ED) attendances over 11 weeks (16 March to 31 May 2020). Computed tomography pulmonary angiogram (CTPA) for PE was performed in 123 patients within 48 h of ED presentation, of whom 118 had D-dimer results. The remaining 875 attendances had D-dimer performed. RESULTS: CTPA performed in 11.8% of patients within 48 h of ED presentation confirmed PE in 37.4% (46/123). Thrombosis was observed at all levels of pulmonary vasculature with and without right ventricular strain. In the CTPA cohort, patients with PE had significantly higher D-dimer, prothrombin time, C-reactive protein, troponin, total bilirubin, neutrophils, white cell count and lower albumin compared with non-PE patients. However, there was no difference in the median duration of inpatient stay or mortality. A receiver operator curve analysis demonstrated that D-dimer could discriminate between PE and non-PE COVID-19 patients (area under the curve of 0.79, p < 0.0001). Furthermore, 43% (n = 62/145) of patients with D-dimer >5000 ng/ml had CTPA with PE confirmed in 61% (n = 38/62), that is, 26% of >5000 ng/ml cohort. The sensitivity and specificity were related to D-dimer level; cutoffs of 2000, 3000, 4000, and 5000 ng/ml, respectively, had a sensitivity of 93%, 90%, 90% and 86%, and a specificity of 38%, 54%, 59% and 68%, and if implemented, an additional 229, 141, 106 and 83 CTPAs would be required. CONCLUSION: Our data suggested an increased PE prevalence in COVID-19 patients attending ED with an elevated D-dimer, and patients with levels >5000 ng/ml might benefit from CTPA to exclude concomitant PE.