Severe Morbidity and Mortality Associated With Respiratory Syncytial Virus Versus Influenza Infection in Hospitalized Older Adults

Background. Respiratory syncytial virus (RSV) is an important cause of serious respiratory illness in older adults. Comparison of RSV and influenza infection in hospitalized older adults may increase awareness of adult RSV disease burden. Methods. Hospitalized adults aged >= 60 years who tested positive for RSV or influenza between 1 January 2011 and 30 June 2015 were identified from Kaiser Permanente Southern California electronic medical records. Baseline characteristics, comorbidities, utilization, and outcomes were compared. Results. The study included 645 RSV- and 1878 influenza-infected hospitalized adults. Patients with RSV were older than those with influenza (mean, 78.5 vs 77.4 years; P =.035) and more likely to have congestive heart failure (35.3% vs 24.5%; P <.001) and chronic obstructive pulmonary disease (COPD) (29.8% vs 24.3%; P =.006) at baseline. In adjusted analyses, RSV infection was associated with greater odds of length of stay >= 7 days (odds ratio [OR] = 1.5; 95% confidence interval [CI], 1.2-1.8; P <.001); pneumonia (OR = 2.7; 95% CI, 2.2-3.2; P <.001); intensive care unit admission (OR = 1.3; 95% CI, 1.0-1.7; P =.023); exacerbation of COPD (OR = 1.7; 95% CI, 1.3-2.4; P =.001); and greater mortality within 1 year of admission (OR = 1.3; 95% CI, 1.0-1.6; P =.019). Conclusions. RSV infection may result in greater morbidity and mortality among older hospitalized adults than influenza. Increased recognition of adult RSV disease burden will be important in the evaluation and use of new RSV vaccines and antivirals.