Thrombosis in hospitalized patients with viral respiratory infections versus COVID-19

We evaluated the incidence of thrombosis in patients hospitalized with non-COVID-19 acute viral respiratory illnesses nationwide from 2012 to 2014 and compared this to the incidence among patients hospitalized with COVID-19 at a large health system in New York. Non-COVID-19 viral respiratory illness was complicated by acute MI in 2.8% of hospitalizations, VTE in 1.6%, ischemic stroke in 0.7%, and other systemic embolism in 0.1%. The proportion of hospitalizations complicated by thrombosis was lower in patients with viral respiratory illness in 2002-2014 than in COVID-19 (5% vs 16%; P< .001). BACKGROUND: Thrombosis is a prominent feature of the novel Coronavirus disease 2019 (COVID-19). The incidence of thrombosis during hospitalization for non-COVID-19 viral respiratory infections is uncertain. We evaluated the incidence of thrombosis in patients hospitalized with non-COVID-19 acute viral respiratory illnesses compared to COVID-19. METHODS: Adults age >18 years hospitalized with a non-COVID-19 viral respiratory illness between 2002 and 2014 were identified. The primary study outcome was a composite of venous and arterial thrombotic events, including myocardial infarction (MI), acute ischemic stroke, and venous thromboembolism (VTE), as defined by ICD-9 codes. The incidence of thrombosis in non-COVID-19 viral respiratory illnesses was compared to the recently published incidence of thrombosis in COVID-19 from 3,334 patients hospitalized in New York in 2020. RESULTS: Among 954,521 hospitalizations with viral pneumonia from 2002 to 2014 (mean age 62.3 years, 57.1% female), the combined incidence of arterial and venous thrombosis was 5.0%. Acute MI occurred in 2.8% of hospitalizations, VTE in 1.6%, ischemic stroke in 0.7%, and other systemic embolism in 0.1%. Patients with thrombosis had higher in-hospital mortality (14.9% vs 3.3%, P< .001) than those without thrombosis. The proportion of hospitalizations complicated by thrombosis was lower in patients with viral respiratory illness in 2002-2014 than in COVID-19 (median age 64; 39.6% female) in 2020 (5% vs 16%; P< .001) CONCLUSION: In a nationwide analysis of hospitalizations for viral pneumonias, thrombosis risk was lower than that observed in patients with COVID-19. Investigations into mechanisms of thrombosis and risk reduction strategies in COVID-19 and other viral respiratory infections are necessary.