In-hospital mortality significantly higher with COVID-19 than flu
Patients hospitalized with COVID-19 had a mortality risk that was nearly 3.5 times higher than those hospitalized with influenza, according to a study published in the Canadian Medical Association Journal.
“We can now say definitively that COVID-19 is much more severe than seasonal influenza,” Amol A. Verma, MD, MPhil, BSc, a general internal medicine resident at St. Michael’s Hospital, Unity Health Toronto, and the University of Toronto, said in a press release. “Patients admitted to hospital in Ontario with COVID-19 had a 3.5 times greater risk of death, 1.5 times greater use of the ICU and 1.5 times longer hospital stays than patients admitted with influenza.”
Verma and colleagues conducted a retrospective cohort study using information from seven hospitals in Toronto and Ontario. They evaluated adults admitted to the ICU between November 1, 2019, and June 30, 2020.
A total of 783 admissions for influenza and 1,027 admissions for COVID-19 were included in the study. The researchers noted that these admissions made up 23.5% of all COVID-19 hospital admissions in Ontario during the study period.
Patients aged younger than 50 years accounted for 21.2% of all COVID-19 admissions and 24% of ICU admissions for COVID-19.
The researchers determined that patients admitted with COVID-19 had significantly greater in-hospital mortality compared with those hospitalized with influenza (19.9% vs. 6.1%; adjusted RR [aRR] = 3.46; 95% CI, 2.56-4.68).
They also found that patients with COVID-19 had significantly greater ICU use compared with those with influenza (26.4% vs. 18%; aRR = 1.5; 95% CI, 1.25-1.80).
Additionally, patients with COVID-19 had longer length of stay in the hospital, with a median of 8.7 days compared with 4.8 days among patients with influenza (aRR = 1.45; 95% CI, 1.25-1.69).
According to the researchers, patients with COVID-19 were more likely than those with influenza to undergo invasive mechanical ventilation (18.5% vs. 9.3%; P = 0.001) but were less likely to undergo a bronchoscopy (2% vs. 5.6%; P = 0.005).
The rate of readmission at 30 days was not significantly different between patients admitted with COVID-19 and those with influenza (aRR = 0.98; 95% CI, 0.70-1.39).
“These differences may be magnified by low levels of immunity to the novel coronavirus compared with seasonal influenza, which results from past infections and vaccination,” Verma said in the press release. “Hopefully, the severity of COVID-19 will decrease over time as people are vaccinated against the virus and more effective treatments are identified. There is, unfortunately, also the possibility that variants of the virus could be even more severe.”