Factors associated with severe health outcomes among community-dwelling older adults hospitalized with respiratory syncytial virus

Objectives — We describe the burden of respiratory syncytial virus (RSV)-related hospitalization among community-dwelling older adults in the pre-vaccine era and identify factors associated with adverse hospital outcomes.

Methods — We conducted a population-based retrospective cohort study among adults aged ≥50 years hospitalized with RSV, using linked laboratory and health administrative data in Ontario, Canada during 2017–2020. We used modified Poisson regression models to assess associations between 25 individual factors and four hospital-related outcomes (30-day mortality, intensive care unit [ICU] utilization, hospital length of stay [LOS], and 30-day readmission).

Results — Of 3221 adults hospitalized with RSV, 314 (9.7%) died within 30 days, 560 (17.4%) required ICU care, and the median (interquartile range) LOS was 6 (3–11) days. Of 2913 adults discharged alive, 343 (11.8%) were readmitted within 30 days. Frailty strongly predicted all outcomes: mortality (adjusted risk ratio [aRR]=1.36; 95%CI, 1.05–1.76), ICU (aRR=1.45; 95%CI, 1.22–1.73), LOS (adjusted incidence rate ratio [IRR]=1.96; 95%CI, 1.81–2.12), and readmission (aRR=1.46; 95%CI, 1.14–1.87). Adults aged ≥90 years (aRR=2.37; 95%CI, 1.32–4.24), those with active cancer (aRR=1.63; 95%CI, 1.17–2.27) or other immunodeficiencies (aRR=1.54; 95%CI, 1.21–1.95), and chronic home care recipients (aRR=1.32; 95%CI, 1.03–1.67) had a higher risk of mortality, with similar trends observed for readmission.

Conclusions — RSV causes substantial morbidity and mortality among hospitalized older adults. These findings help identify high-risk groups for vaccine prioritization.