RSV Epidemiology and Clinical Outcomes in Adults ≥60 Years of Age Seeking Outpatient Care for Respiratory Illness

Abstract

Background. Knowledge of RSV epidemiology in adults is needed to estimate the potential impact on burden of illness when a vaccine is licensed. We evaluated clinical features and outcomes among older adults with outpatient RSV illness over 12 seasons. Methods. Adults ≥ 60 years old in a community cohort were enrolled in seasonal studies of influenza vaccine effectiveness from 2004-05 through 2015-16. Individuals seeking outpatient care for acute respiratory illness completed a symptom interview and relevant clinical data were extracted from electronic medical records. Multiplex RT-PCR testing was later performed on archived respiratory swabs to identify RSV A and B. RSV outcomes within 28 days were classified as serious (hospital admission, ED visit, or x-ray confirmed pneumonia), moderate (new antimicrobial, antiviral, bronchodilator, or systemic corticosteroid treatment) or mild (all others). Incidence of medically attended RSV in the community cohort was estimated by extrapolating results from enrolled patients to non-enrolled patients seeking outpatient care with acute respiratory illness. Results. 243 (11%) of 2257 samples were RSV positive. The mean age of RSV cases was 72 years, 158 (65%) were female, and 81 (33%) had a chronic cardiopulmonary disease (COPD, asthma, and/or CHF). The RSV clinical outcome was serious in 45 (19%), moderate in 157 (65%), and mild in 41 (17%) patients. Among those with serious RSV outcomes, 28 (62%) were hospitalized, 23 (51%) had pneumonia, and 11 (24%) had an ED visit. Serious RSV outcomes were more common among those with chronic cardiopulmonary disease than those without (30% vs. 17%, P = 0.005). Hospitalized RSV patients spent a median of 3.0 days (range 0-12 days) in the hospital. The seasonal incidence of medically attended RSV was 139 cases per 10,000. The incidence was similar for RSV A and B. Individuals with COPD compared with those without COPD, had an approximately two fold higher incidence of RSV (incidence rate ratio 1.9, 95% CI 1.4?2.5). Conclusion. The majority of adults ≥ 60 years old with outpatient RSV have moderate or serious clinical outcome. Those with chronic cardiopulmonary disease had higher incidence of RSV and experienced serious clinical outcomes more frequently.