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Evidence suggested that COVID-19 infection may induce a hypercoagulable state resulting in arterial thromboembolism (ATE) or venous thromboembolism (VTE). However, studies examining thrombotic complications from COVID-19 to date had included small samples, rarely included a comparator group, and had not evaluated characteristics associated with these outcomes. FDA initiated this study in the Sentinel System to determine the 90-day incidence of hospitalized ATE and VTE in patients with COVID-19 and subsequent 30-day mortality, identify risk factors for ATE and VTE events, and compare the incidence of ATE and VTE among patients with COVID-19 vs. patients with influenza. Patients were evaluated separately based on the setting (outpatient vs. inpatient) and timing (before vs. during COVID-19 vaccination availability) of their COVID-19 diagnosis.
Among patients hospitalized with COVID-19, the 90-day absolute risks of ATE and VTE were 15.8%-16.3% and 9.5%-10.9%, respectively (range represents periods before and during vaccine availability). Compared with patients with influenza, the risk of ATE was not significantly higher among patients with COVID-19 either before or during vaccine availability; however, risk of VTE was significantly higher among patients with COVID-19 before (HR 1.60; 95% CI: 1.43-1.79) and during vaccine availability (HR 1.89; 95% CI: 1.68-2.12). Among those with an ATE or VTE event, 30-day mortality was significantly higher in patients with inpatient-diagnosed COVID-19 versus influenza both before vaccine availability [(ATE: HR 3.45; 95% CI: 2.68-4.45) (VTE: HR 2.96; 95% CI: 1.84-4.76)] and during vaccine availability [(ATE: HR 3.45; 95% CI: 2.69-4.44) (VTE: HR 3.80; 95% CI: 2.41-6.00)].
Among patients with ambulatory-diagnosed COVID-19, the 90-day absolute risks of hospitalized ATE and VTE were 1.01%-1.06% and 0.73%-0.88%, respectively. Compared with patients with influenza, the risk of ATE was higher among patients with COVID-19 both before (HR 1.53; 95% CI: 1.38-1.69) and during vaccine availability (HR 1.69; 95% CI: 1.53-1.86). Risk of VTE also was higher among patients with COVID-19 before (HR 2.86; 95% CI: 2.46-3.32) and during vaccine availability (HR 3.56; 95% CI: 3.08-4.12). Among those with an ATE or VTE event, 30-day mortality was significantly higher in patients with ambulatory-diagnosed COVID-19 versus influenza both before vaccine availability [(ATE: HR 2.65; 95% CI: 1.88-3.73) (VTE: HR 2.36; 95% CI: 1.34-4.18)] and during vaccine availability [(ATE: HR 2.53; 95% CI: 1.82-3.51) (VTE: HR 2.58; 95% CI: 1.48-4.50)]. The results from this study informed FDA’s public health response during the COVID-19 pandemic.