Burden of Respiratory Syncytial Virus Disease Among Adults in the United States From 1997 to 2012

Abstract

Objectives: The burden of illness caused by respiratory syncytial virus (RSV) in adults has not been well-studied. Methods: Annual hospitalization rates for RSV in adults 20 years and older were estimated using weighted counts from the National Inpatient Sample (NIS), a nationally representative database, and US Census data for denominators. RSV disease was identified by ICD9 coding. Patients were classified as immunocompromised or not based on an existing AHRQ algorithm (AHRQ 2006). Hospitalizations were characterized by diagnostic categories, in-patient mortality, length of stay (LOS), mechanical ventilation use and total cost (2015$). Poisson and linear regression were used to test statistical significance of trends. Results: 28,237 RSV patients were identified, with 34% classified as immunocompromised. RSV hospitalizations occurred more often in those 60 and older (58%), female (57%), and non-Hispanic white (61%). Most adult RSV hospitalizations occur between December and April. The rate of RSV hospitalizations increased from 0.27 to 1.93 per 100,000 per year over the 15-year period. The largest increase in rates was for non-immunocompromised women age 60 and older. A higher proportion of immunocompromised patients died in hospital than non-immunocompromised patients (7.6% vs. 5.6%, p= 0.01), but use of mechanical ventilation was not increased (15% vs. 18%, p= 0.02). The mean LOS for immunocompromised individuals vs. not immunocompromised was 7.4 days vs. 5.5 days (p< 0.01), with a mean cost of $66,476 vs. $29,316 (p< 0.01). Conclusions: RSV-coded hospitalization rates in adults increased between 1997 and 2012. It is not possible to determine from the data if this represents a change in epidemiology or a change in testing practice leading to greater specificity of viral diagnoses. RSV disease was more severe in immunocompromised patients with higher mortality, longer LOS, and higher total cost. Adult RSV merits further research, and immunocompromised populations would benefit from interventions to prevent or treat disease.