Study Outcomes and Risk Factors Associated with Severe RSV Infection
The primary outcome was the proportion of patients with severe RSV outcomes, defined as being admitted to an ICU, receiving mechanical ventilation, and/or dying during the RSV-associated hospitalization. The Centers for Disease Control and Prevention National Notifiable Diseases Surveillance System case definition for RSV-related death was used.14
Potential factors associated with severe RSV infection were assessed and included demographic characteristics, comorbid conditions, study hospital, study year, and living situation at the time of admission as described in the EMR. The baseline living situations of patients were stratified by implied level of functional independence. Level 1 included patients living without assistance in the community; Level 2 included those living in the community with the assistance of friends, family, and/or a home health aide; and Level 3 included those living in a facility such as assisted living, a skilled nursing or long-term care facility, rehabilitation facility, or hospice. Patients who reported being homeless on admission or were transferred from another acute care facility were excluded from this analysis.
Among the patients who survived and were discharged from the hospital, we explored changes in living situation from admission to discharge that implied the need for a higher level of care at discharge. For example, living with assistance on admission (Level 2) and discharge to a skilled nursing home (Level 3) represented the need for a higher level of care. Patients who were discharged to another acute care facility were excluded from this analysis.