Predictors of all-cause mortality among patients hospitalized with influenza, respiratory syncytial virus or SARS-CoV-2

This paper is published in Influenza and Other Respiratory Viruses.

Why did we conduct this study?

When a new virus emerges (e.g., SARS-CoV-2, the virus that causes COVID-19), we know little about how the infection may cause disease, and who is at greatest risk of severe illness or death.  It can be helpful to use our knowledge and experience with other similar viruses to inform early clinical and public health responses to the new virus.

What did we do?

We used population-based data on individuals living in Ontario, Canada who were cared for within the publicly funded healthcare system.  We assessed whether predictors of mortality among patients hospitalized with SARS-CoV-2 were similar (i.e., shared predictors) or different (i.e., divergent predictors) to predictors of death among patients hospitalized with two other clinically important respiratory viruses: influenza, and respiratory syncytial virus (RSV). The outcome we measured was risk of death within 30 days of hospital admission with influenza, RSV, or SARS-CoV-2.  We compared all potential predictors including demographic characteristics (e.g., age, sex), underlying health conditions (e.g., asthma, heart disease), and neighborhood-level social determinants of health (e.g., median income, percent racialized).

What did we find?

The following were shared predictors of mortality among patients hospitalized with any of the three respiratory viruses studied: older age, male sex, residence in a long-term care home, and chronic kidney disease.

What does this mean for health systems?

First, when patients are admitted to the hospital with a respiratory virus, and we do not know much about the virus (e.g., when a new respiratory virus emerges), these shared predictors of mortality can help us identify patients who are more likely to be at risk of severe illness or death in early stages of their illness. Second, if we know how common shared predictors of mortality are in communities, then health systems can efficiently allocate and ensure there are enough resources (e.g., vaccines, therapeutics, hospital beds, support for health care workers) to meet the needs of each community.

The study was led by Mackenzie Hamilton, conducted at ICES, and supported by the Canadian Institutes of Health Research Rapid COVID Grant and St. Michael’s Foundation.

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