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.