COVID-19, influenza, and vascular thrombotic events
The association of COVID-19 with thrombotic events was initially inferred from case series. Now, investigators have analysed U.S. claims and medical records data to evaluate incidence of inpatient arterial and venous thrombotic events among adults hospitalised with COVID-19 between April 1, 2020, and May 31, 2021 (41,443 before vaccine availability and 44,194 after). Controls comprised 8,269 adults hospitalised with influenza during the 2018–2019 season.
The adjusted 90-day risk for developing arterial thrombosis was no different between patients with COVID-19 or influenza, both before and after COVID-19 vaccine availability (hazard ratio [HR], 1.04–1.07). In patients who experienced an arterial thrombotic event, subsequent 30-day mortality risk was higher among those with COVID-19 compared with influenza (HR, 3.45 whether before or after vaccine availability).
Adjusted risk for developing venous thrombosis was higher among patients with COVID-19 than influenza (HR, 1.60 [before vaccine] and 1.89 [after vaccine]). Following a venous thrombotic event, 30-day mortality risk was higher in patients with COVID-19 compared with influenza (HR, 2.96 [before vaccine] and 3.80 [after vaccine]). These data support an increased risk for venous, but not arterial, thrombotic events with COVID-19 hospitalisation relative to influenza hospitalisation.
The authors stratify the observation period by COVID-19 vaccine availability dates — however, prior to the emergence of the Delta variant (summer of 2021), patients admitted with severe COVID-19 were largely unimmunised. Because these data largely reflect the prevaccine era, examining this question in the current setting of relatively high population immunity is warranted.
Source: Journal Watch
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