Background Whereas accumulating studies on COVID‐19 patients report high incidences of thrombotic complications, large studies on clinically relevant thrombosis in patients with other respiratory tract infections are lacking. How this high risk in COVID‐19 patients compares to those observed in hospitalized patients with other viral pneumonias such as influenza is unknown. Objectives To assess the incidence of venous and arterial thrombotic complications in hospitalized influenza patients as opposed to that observed in hospitalized COVID‐19 patients. Methods Retrospective cohort study; we used data from Statistics Netherlands (study period: 2018) on thrombotic complications in hospitalized influenza patients. In parallel, we assessed the cumulative incidence of thrombotic complications – adjusted for competing risk of death ‐ in patients with COVID‐19 in three Dutch hospitals (February 24th ‐ April 26th 2020). Results Of the 13.217 hospitalized influenza patients, 437 (3.3%) were diagnosed with thrombotic complications, versus 66 (11%) of the 579 hospitalized COVID‐19 patients. The 30‐day cumulative incidence of any thrombotic complication in influenza was 11% (95%CI 9.4‐12) versus 25% (95%CI 18‐32) in COVID‐19. For venous thrombotic complications (VTE) and arterial thrombotic complications alone, these numbers were respectively 3.6% (95%CI 2.7‐4.6) and 7.5% (95%CI 6.3‐8.8) in influenza versus 23% (95%CI 16‐29) and 4.4% (95%CI 1.9‐8.8) in COVID‐19. Conclusions The incidence of thrombotic complications in hospitalized influenza patients was lower than in hospitalized COVID‐19 patients. This difference was mainly driven by a high risk of VTE complications in the COVID‐19 patients admitted to ICU. Remarkably, influenza patients were more often diagnosed with arterial thrombotic complications.

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Background Diagnostic strategies for suspected pulmonary embolism (PE) have not been prospectively evaluated in COVID-19 patients. Methods Prospective, multicenter, outcome study in 707 patients with both (suspected) COVID-19 and suspected PE in 14 hospitals. Patients on chronic anticoagulant therapy were excluded. Informed consent was obtained by opt-out approach. Patients were managed by validated diagnostic strategies for suspected PE. We evaluated the safety (3-month failure rate) and efficiency (number of computed tomography pulmonary angiographies [CTPAs] avoided) of the applied strategies. Results Overall PE prevalence was 28%. YEARS was applied in 36%, Wells rule in 4.2%, and “CTPA only” in 52%; 7.4% was not tested because of hemodynamic or respiratory instability. Within YEARS, PE was considered excluded without CTPA in 29%, of which one patient developed nonfatal PE during follow-up (failure rate 1.4%, 95% CI 0.04–7.8). One-hundred seventeen patients (46%) managed according to YEARS had a negative CTPA, of whom 10 were diagnosed with nonfatal venous thromboembolism (VTE) during follow-up (failure rate 8.8%, 95% CI 4.3–16). In patients managed by CTPA only, 66% had an initial negative CTPA, of whom eight patients were diagnosed with a nonfatal VTE during follow-up (failure rate 3.6%, 95% CI 1.6–7.0). Conclusion Our results underline the applicability of YEARS in (suspected) COVID-19 patients with suspected PE. CTPA could be avoided in 29% of patients managed by YEARS, with a low failure rate. The failure rate after a negative CTPA, used as a sole test or within YEARS, was non-negligible and reflects the high thrombotic risk in these patients, warranting ongoing vigilance.

BackgroundWhereas accumulating studies on COVID-19 patients report high incidences of thrombotic complications, large studies on clinically relevant thrombosis in patients with other respiratory tract infections are lacking. How this high risk in COVID-19 patients compares to those observed in hospitalized patients with other viral pneumonias such as influenza is unknown.ObjectivesTo assess the incidence of venous and arterial thrombotic complications in hospitalized influenza patients as opposed to that observed in hospitalized COVID-19 patients.MethodsRetrospective cohort study; we used data from Statistics Netherlands (study period: 2018) on thrombotic complications in hospitalized influenza patients. In parallel, we assessed the cumulative incidence of thrombotic complications – adjusted for competing risk of death - in patients with COVID-19 in three Dutch hospitals (February 24th - April 26th 2020).ResultsOf the 13.217 hospitalized influenza patients, 437 (3.3%) were diagnosed with thrombotic complications, versus 66 (11%) of the 579 hospitalized COVID-19 patients. The 30-day cumulative incidence of any thrombotic complication in influenza was 11% (95%CI 9.4-12) versus 25% (95%CI 18-32) in COVID-19. For venous thrombotic complications (VTE) and arterial thrombotic complications alone, these numbers were respectively 3.6% (95%CI 2.7-4.6) and 7.5% (95%CI 6.3-8.8) in influenza versus 23% (95%CI 16-29) and 4.4% (95%CI 1.9-8.8) in COVID-19.ConclusionsThe incidence of thrombotic complications in hospitalized influenza patients was lower than in hospitalized COVID-19 patients. This difference was mainly driven by a high risk of VTE complications in the COVID-19 patients admitted to ICU. Remarkably, influenza patients were more often diagnosed with arterial thrombotic complications.EssentialsIt is unknown how COVID-19 compares to patients with other virus infections regarding thrombosis.Hospitalized patients with influenza and COVID-19 were evaluated and compared to each other.30-day cumulative incidence of thrombosis was lower in influenza (11%) than in COVID-19 (25%).Difference was mainly driven by a high risk of VTE in COVID-19 patients admitted to the ICU.