Age, Sex, Kidney Disease Predict Mortality for Patients Hospitalized With Respiratory Diseases

Older age, male sex, residence in a long-term care home, and chronic kidney disease were found to be shared predictors of increased mortality for patients hospitalized with influenza, respiratory syncytial virus (RSV), or SARS-CoV-2, according to a recent study published in Influenza and Other Respiratory Viruses.

Researchers also found associations between mortality rates and comorbidities, immunization against influenza, and geographical location, although these associations varied in strength by disease.

“Knowing who is at highest risk of severe disease from respiratory viruses may support proactive clinical decision-making and help distribute resources to health care settings with high prevalence of risk factors,” wrote the authors. “This is particularly useful in the context of a new and emerging respiratory virus where information and resources are scarce.”

The researchers conducted a retrospective cohort study to identify predictors of 30-day all-cause mortality following hospitalization with influenza, RSV, or SARS-CoV-2. Population-based laboratory and administrative data were gathered from Ontario, Canada.

The investigators assessed associations between potential predictors and mortality by comparing direction, magnitude, and CIs of risk ratios among the 3 study cohorts.

They observed a total of 45,749 influenza hospitalizations, 24,345 RSV hospitalizations, and 8988 SARS-CoV-2 hospitalizations after applying both inclusion and exclusion criteria.

Patients with RSV were generally younger than those in the other cohorts and presented with fewer comorbidities.

The study found that 3186 patients with influenza, 697 patients with RSV, and 1880 patients with SARS-CoV-2 died within 30 days of hospital admission. Patients hospitalized with SARS-CoV-2 had the highest crude 30-day all-cause mortality rate at 20.9%, followed by those with influenza (7.0%) and RSV (2.9%).

Older age, male sex, residence in a long-term care home, and chronic kidney disease were found to be shared predictors of increased mortality.

Positive associations between age and mortality were highest for patients with SARS-CoV-2, supporting previous research. However, few comorbidities were associated with mortality among patients with SARS-CoV-2 compared with patients with influenza or RSV.

The authors suggest that further research is needed to compare the immunological and clinical disease progression of influenza, RSV, and SARS-CoV-2 to better explain observed differences in risk by comorbidity.

Rural residence was found to be associated with increase 30-day all-cause mortality among patients with RSV and SARS-CoV-2 (RSV: adjusted relative risk [RR], 1.52; 95% CI, 1.09-2.12; SARS-CoV-2: adjusted RR, 1.27; 95% CI, 1.01-1.61). Immunization against seasonal influenza was found to be associated with a decreased 30-day all-cause mortality rate among patients with influenza (adjusted RR, 0.89; 95% CI, 0.83-0.96).

For patients with influenza and RSV, cardiac ischemic disease, congestive heart failure, dementia/frailty, and immunosuppression were all associated with increased all-cause mortality.

Associations between area-level social determinants of health and 30-day all-cause mortality following hospitalization were not observed for any cohort, despite their association with transmission risk.

These results of have 3 important implications for clinical care and health care systems, according to the authors:

• Shared predictors of mortality could be used to identify, target, and prioritize hospitalized patients who are at the greatest risk of death for prevention, testing, and therapeutics in the context of a novel respiratory pathogen.
• The underlying prevalence of shared predictors in a given geography could help prepare health systems for and efficiently allocate resources during emergence of a novel respiratory pathogen.
• Differences in observed predictors of mortality across the 3 viruses signal the importance of sufficient virus-specific laboratory testing to identify at-risk individuals.

Therefore, the authors hope their findings may help identify patients at the greatest risk of illness, anticipate hospital resource needs, and prioritize local prevention and therapeutic strategies to communities with higher prevalence of risk factors.

The study had limitations. The data may have captured deaths attributable to the virus or deaths in the context of an incidental infection (ie, death with the virus). The authors estimated that about 3% of deaths for the SARS-CoV-2 outcome in their study may be attributed to death with the virus.

Additionally, the study period’s end date of December 1, 2020, excluded hospitalizations of patients vaccinated against SARS-CoV-2 or those with SARS-CoV-2 variants.

The authors also suggest that there is a lack of data on other predictors, encouraging future research.

Reference

Hamilton MA, Liu Y, Calzavara A, Sundaram ME, Djebli M, Darvin D, et al. Predictors of all-cause mortality among patients hospitalized with influenza, respiratory syncytial virus, or SARS-CoV-2. Influenza Other Respir Viruses. Published online May 24, 2022. doi:10.1111/irv.13004