Is In-Hospital Mortality Risk from Health Care-Associated COVID-19 Comparable to Influenza?

A recent retrospective cohort study comparing the in-hospital mortality and intensive care unit (ICU) admission rates of hospitalized patients with symptomatic health care-associated COVID-19 and influenza found similar mortality rates between the two groups, suggesting that both COVID-19 and influenza continue to cause significant disease in hospitalized patients.

With COVID-19 becoming a more common part of the infectious disease landscape, it is crucial to compare its clinical outcomes with other respiratory diseases such as influenza. Understanding the comparative risks of in-hospital death and ICU admission can help health care systems better manage and allocate resources for these illnesses.

The researchers analyzed data from nine Swiss hospitals, focusing on adults hospitalized for at least 3 days between February 2022 and April 2023 (for COVID-19) and between November 2018 and April 2023 (for influenza). The cohort included 2901 patients with symptomatic health care-associated COVID-19 and 868 patients with symptomatic health care-associated influenza. The primary outcome was 30-day in-hospital mortality, and the secondary outcome was admission to the ICU. The study utilized Cox regression models and inverse probability weighting to account for confounding variables.

The results indicated that the case fatality ratios for health care-associated COVID-19 and influenza were similar, at 6.2% and 6.1%, respectively. After adjusting for confounding factors, the subdistribution hazard ratio for 30-day in-hospital mortality was 0.91 (95% CI, 0.67-1.24), indicating no significant difference in mortality risk between the two groups. The proportion of patients admitted to the ICU was also comparable, at 2.4% for COVID-19 and 2.6% for influenza.

“COVID-19 and influenza continue to cause severe disease among hospitalized patients,” the study authors concluded. “Our results suggest that in-hospital mortality risk of healthcare-associated COVID-19 (Omicron) and healthcare-associated influenza are comparable.”

Reference

Grant R, de Kraker MEA, Buetti N, et al. In-hospital outcomes of healthcare-associated COVID-19 (Omicron) versus healthcare-associated influenza. Clin Infect Dis. Published online November 13, 2024. https://doi.org/10.1093/cid/ciae558