CONCLUSIONS
We found that 19% of patients with RSV-associated hospitalization experienced severe outcomes, including 6.7% who died during hospitalization. The proportion of deaths associated with RSV infection is consistent with previous studies of similar populations (8%1, 5.6%4). ICU admission and/or mechanical ventilation have been shown to be associated with increased morbidity and mortality, longer lengths of hospital stay as well as hospital-associated infections.9 Furthermore, ICU admissions were found to be three to four times more costly than admissions to non-ICU units.10
Previous studies have compared morbidity and mortality in adult patients with RSV-related and influenza-related hospitalizations.11,12 Hospitalized adults in Hong Kong with RSV infection had comparable 30- and 60-day mortality compared to those with influenza, but significantly higher rates of mechanical ventilation (11.1% vs. 6.2%, p=0.003), and extended care in subacute hospitals following discharge (25.2% vs. 19.7%, p=0.027).11 Analysis of Medicaid data in Tennessee found that RSV infection and influenza accounted for a similar estimated number of hospitalizations.12
We found that nearly half of the patients admitted from assisted living, a skilled nursing or long-term care facility, rehabilitation facility, or hospice had severe RSV outcomes. While age and specific comorbidities were not associated with severe disease, those living in a facility prior to admission had 4.43 times the odds of severe disease compared to those living independently or with assistance in the community. Similarly, when controlling for age and comorbidities, those who lived in a facility had 6.64 times the odds of severe RSV infection compared to those living independently or with assistance. These findings suggest that living situation may be a proxy measure of frailty and, in turn, a risk for severe disease.13 Chronic disease, multiple comorbidities, and functional disability are associated with frailty, and frailty has been shown to contribute to older adults’ vulnerability to adverse outcomes from influenza.14,15 Other studies have shown that those in assisted living have higher rates of frailty,16 although it should be noted that there are inconsistent measures of frailty. Future interventions for RSV such as vaccines or antiviral therapy should target this vulnerable high-risk population.
Furthermore, we found that 15.1% of adults who survived hospitalization required an increased level of care as reflected in their living situation at discharge when compared with that on admission. Overall, 36 patients (9.7%) went from living in the community to living in a facility. Other studies have shown that hospitalization is an independent risk factor for declines in functional status among older adults which can be associated with a need for increased level of care.17 The yearly median cost of assisted living was estimated to be $48,612 in 2019.18 Thus, studies of healthcare costs associated with RSV hospitalizations should include those incurred after discharge as the need for an increased level of support after discharge will add RSV-related healthcare costs to those already incurred from hospitalization.
This study had limitations. This study was performed in an urban, academically affiliated medical center and the findings may not be generalizable. Although patients had laboratory-confirmed RSV infection and at least two symptoms of ARI, their outcomes, including severe outcomes, may have been secondary to exacerbations of their comorbid conditions. Assessment of comorbidities were collected as reported in the admission notes, but were not verified by treatment, did not account for disease severity, or management during hospitalization. Living situation was self-reported or reported by a family member and not otherwise verified. Living situation might not be due to health-related issues, e.g., patients could be living with a family member due to financial constraints or to assist with childcare.
There are currently no specific therapies or approved vaccines for prevention of RSV infection in adults. These data further highlight the need for prevention strategies for RSV infection in older populations, especially those living in residential living facilities. While frail, older adults may have a diminished capacity to respond to vaccines, prevention of RSV transmission in congregate settings is highly desirable and feasible. Infection prevention strategies combined with vaccination could reduce morbidity and mortality as well as healthcare costs. Future studies should further assess the association of living situation and adverse outcomes as well as the association of RSV-related hospitalizations and longer-term deterioration in functional status.