Hospital outcomes of community-acquired COVID-19 versus influenza: Insights from the Swiss hospital-based surveillance of influenza and COVID-19

  1. Georg Marcus Fröhlich
  2. Marlieke E. A. De Kraker
  3. Mohamed Abbas
  4. Olivia Keiser
  5. Amaury Thiabaud
  6. Maroussia Roelens
  7. Alexia Cusini
  8. Domenica Flury
  9. Peter W. Schreiber
  10. Michael Buettcher
  11. Natascia Corti
  12. Danielle Vuichard-Gysin
  13. Nicolas Troillet
  14. Julien Sauser
  15. Roman Gaudenz
  16. Lauro Damonti
  17. Carlo Balmelli
  18. Anne Iten
  19. Andreas Widmer
  20. Stephan Harbarth
  21. Rami Sommerstein

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Abstract

Since the onset of the COVID-19 pandemic, the disease has frequently been compared with seasonal influenza, but this comparison is based on little empirical data.

Aim

This study compares in-hospital outcomes for patients with community-acquired COVID-19 and patients with community-acquired influenza in Switzerland.

Methods

This retrospective multi-centre cohort study includes patients > 18 years admitted for COVID-19 or influenza A/B infection determined by RT-PCR. Primary and secondary outcomes were in-hospital mortality and intensive care unit (ICU) admission for patients with COVID-19 or influenza. We used Cox regression (cause-specific and Fine-Gray subdistribution hazard models) to account for time-dependency and competing events with inverse probability weighting to adjust for confounders.

Results

In 2020, 2,843 patients with COVID-19 from 14 centres were included. Between 2018 and 2020, 1,381 patients with influenza from seven centres were included; 1,722 (61%) of the patients with COVID-19 and 666 (48%) of the patients with influenza were male (p < 0.001). The patients with COVID-19 were younger (median 67 years; interquartile range (IQR): 54–78) than the patients with influenza (median 74 years; IQR: 61–84) (p < 0.001). A larger percentage of patients with COVID-19 (12.8%) than patients with influenza (4.4%) died in hospital (p < 0.001). The final adjusted subdistribution hazard ratio for mortality was 3.01 (95% CI: 2.22–4.09; p < 0.001) for COVID-19 compared with influenza and 2.44 (95% CI: 2.00–3.00, p < 0.001) for ICU admission.

Conclusion

Community-acquired COVID-19 was associated with worse outcomes compared with community-acquired influenza, as the hazards of ICU admission and in-hospital death were about two-fold to three-fold higher.

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  1. Version published to 10.2807/1560-7917.es.2022.27.1.2001848
  2. ScreenIT

    SciScore for 10.1101/2020.11.17.20233080: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: The study was approved by the Ethics Committee of the Canton of Geneva, Switzerland. (CCER 2018-00577, 2020-00827).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    The present study has several limitations. The impact of various treatment strategies could not be analyzed in the presented Swiss cohort. It can be assumed that mortality for the included COVID-19 patients was relatively high, since the majority of the presented cases occurred early during the COVID-19 pandemic, and knowledge about the best supportive treatment strategies has slowly increased over time. For influenza treatment strategies have been more clearly defined, so the current findings may not apply to future COVID-19 cases.Of note, ∼1/3 of comorbidity data was missing, because it was not mandatory for the surveillance. As it was missing at random, specific centers did not report this data, we carried out a complete cases analysis for the primary outcome. The point-estimate of the complete case analysis fell within the 95% CI of the main analysis, indicating that absence of this data did not introduce a major bias. Post-discharge follow-up was not available neither for influenza nor for COVID-19 patients, as such differences in long-term morbidity could not be discerned while it is assumed that these may have a higher incidence among COVID-19 cases. Finally, since no data was available for co-infection with influenza and SARS-CoV 2 this could not be considered. However, a study from Wuhan found that only 4% of COVID-19 patients had a co-infection with influenza, 25 and no difference in the course of disease was noted in comparison to COVID-19 alone25.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  3. Version published to 10.1101/2020.11.17.20233080 on medRxiv