Estimation of Admission D-dimer Cut-off Value to Predict Venous Thrombotic Events in Hospitalized COVID-19 Patients: Analysis of the SEMI-COVID-19 Registry.

Background: Venous thrombotic events (VTE) are frequent in COVID-19, and elevated plasma D-dimer (pDd) and dyspnea are common in both entities.

Objective: To determine the admission pDd cut-off value associated with in-hospital VTE in patients with COVID-19.

Methods: Multicenter, retrospective study analyzing the at-admission pDd cut-off value to predict VTE and anticoagulation intensity along hospitalization due to COVID-19.

Results: Among 9386 patients, 2.2% had VTE: 1.6% pulmonary embolism (PE), 0.4% deep vein thrombosis (DVT), and 0.2% both. Those with VTE had a higher prevalence of tachypnea (42.9% vs. 31.1%; p = 0.0005), basal O2 saturation <93% (45.4% vs. 33.1%; p = 0.0003), higher at admission pDd (median [IQR]: 1.4 [0.6-5.5] vs. 0.6 [0.4-1.2] μg/ml; p < 0.0001) and platelet count (median [IQR]: 208 [158-289] vs. 189 [148-245] platelets × 10/L; p = 0.0013). A pDd cut-off of 1.1 μg/ml showed specificity 72%, sensitivity 49%, positive predictive value (PPV) 4%, and negative predictive value (NPV) 99% for in-hospital VTE. A cut-off value of 4.7 μg/ml showed specificity of 95%, sensitivity of 27%, PPV of 9%, and NPV of 98%. Overall mortality was proportional to pDd value, with the lowest incidence for each pDd category depending on anticoagulation intensity: 26.3% for those with pDd >1.0 μg/ml treated with prophylactic dose (p < 0.0001), 28.8% for pDd for patients with pDd >2.0 μg/ml treated with intermediate dose (p = 0.0001), and 31.3% for those with pDd >3.0 μg/ml and full anticoagulation (p = 0.0183).

Conclusions: In hospitalized patients with COVID-19, a pDd value greater than 3.0 μg/ml can be considered to screen VTE and to consider full-dose anticoagulation.