The Association of Anticoagulation Intensity with Outcomes in Hospitalized COVID-19 Patients

Venous thromboembolism (VTE) risk is increased in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A key question was whether increased intensity of anticoagulation would help prevent VTE and improve patient outcomes, including transfer to the intensive care unit (ICU) and mortality. At the start of the coronavirus disease-19 (COVID-19) pandemic, our institution, Boston Medical Center, instituted a VTE risk stratification protocol based on patients' initial D-dimer levels, medical history, and presence of thrombosis to determine whether they should receive standard-dose prophylaxis, high-dose prophylaxis, or therapeutic anticoagulation. We performed a retrospective observational cohort study examining the association of degree of anticoagulation with outcomes in 915 hospitalized COVID-19 patients hospitalized initially on the general inpatient wards between March 1,^, 2020, and June 1, 2020. Patients directly hospitalized in the ICU were excluded. Most, 813 patients (89%), in our cohort were on standard-dose prophylaxis; 32 patients (3.5%) received high-dose prophylaxis; 70 patients (7.7%), were treated with therapeutic anticoagulation. VTE occurred in 45 patients (4.9%), and the overall in-hospital mortality rate was 5.4% (49 deaths). On multivariable analysis of clinical outcomes in relation to type of anticoagulation, in the high-dose prophylaxis group, there was a trend towards increased in-hospital mortality (odds ratio 2.4 (0.8-7.5, 95% CI)) and increased ICU transfer (odds ratio 2.2 (0.9-5.7, 95% CI)). Our results suggest that patients receiving high-dose prophylaxis had more severe disease that was not mitigated by intermediate-dose anticoagulation.