P-715. Chronic Conditions as Risk Factors for Respiratory Syncytial Virus-Associated Hospitalization among Community-Dwelling Adults Aged ≥50 Years, 2017 to 2018
Authors: Woodruff Rebecca C , Hamid Sarah , Pham Huong , Derado Gordana , Taylor Christopher , Sekkarie Ahlia , Loustalot Fleetwood , Lundeen Elizabeth , Kirley Pam Daily , Austin Elizabeth , Witt Lucy S , Ryan Patricia A , Reeg Libby , Lynfield Ruth , Pacheco Francesca , Keating Fiona , St George Katherine , Thomas Ann , Talbot Keipp , Hill Mary , Havers Fiona P , Melgar Michael 
Published: January 2025

Abstract

Background
In 2023, CDC recommended respiratory syncytial virus (RSV) vaccination for adults aged ≥ 60 years using shared clinical decision-making. Clinical trials of RSV vaccines in younger age groups are ongoing. Identifying chronic conditions associated with increased RSV hospitalization risk can inform vaccination policy.Figure 1.Prevalence of chronic medical conditions among community-dwelling adults aged ≥50 years hospitalized with respiratory syncytial virus (RSV),1 in RSV-NET states,2 and in 50 US states and the District of Columbia2Abbreviations: BMI: body mass index (kg/m2), COPD: chronic obstructive pulmonary disease
1 Prevalence of chronic conditions indicated in the medical record among community-dwelling adults aged ≥50 years hospitalized with laboratory-confirmed RSV infection identified by the RSV Hospitalization Surveillance Network (RSV-NET) from October 2017 to April 2018.
2 Weighted prevalence of community-dwelling adults aged ≥50 years in RSV-NET states (CA, GA, MD, MN, NM, NY, OR, TN) or 50 states and the District of Columbia who self-reported history of chronic medical conditions on the 2018 Behavioral Risk Factor Surveillance System.

Methods
We compared RSV hospitalization rates among community-dwelling adults aged ≥ 50 years with and without 9 chronic medical conditions in a 38-county catchment area across 8 states. Rate numerators included hospitalizations in adults with and without medical record documentation of each chronic condition, with laboratory-confirmed RSV infection from October 2017 to April 2018 identified by the RSV Hospitalization Surveillance Network (RSV-NET). Rate denominators were catchment area population counts of adults with and without each chronic condition estimated from the 2018 Behavioral Risk Factor Surveillance System, which relies on self-report, and the US Census. Poisson regression using Monte Carlo simulation generated adjusted rate ratios (aRR) and 95% Monte Carlo confidence intervals (CI), adjusted for age, sex, and race and ethnicity group.Table 1.Adjusted models comparing respiratory syncytial virus (RSV) hospitalization rates among community-dwelling adults aged ≥50 years by number of chronic medical conditions— RSV Hospitalization Surveillance Network (RSV-NET), October 2017–April 2018Abbreviations: aRR: adjusted rate ratio; CI: Monte Carlo confidence interval1 aRR and 95% Monte Carlo CI were estimated using Poisson regression and Monte Carlo simulation after adjusting for age group (50-59 years, 60-74 years, ≥75 years), sex, and race and ethnicity group (non-Hispanic White, non-Hispanic Black, and other).2 Includes asthma, chronic obstructive pulmonary disease, chronic kidney disease, coronary artery disease, diabetes, history of stroke, obesity (body mass index 30-39 kg/m2), severe obesity (body mass index ≥40 kg/m2), and current smoking.

Results
Among 1,692 adults aged ≥ 50 years hospitalized with laboratory-confirmed RSV infection, 86.9% had ≥1 chronic condition (Figure 1). RSV hospitalization rates were higher among adults with 1 (aRR=2.7, CI: 1.8, 3.9) or ≥2 chronic conditions (aRR=9.0, CI: 6.3-12.6) vs. none and among adults aged 60-74 years (aRR=1.8, CI: 1.3, 2.6) or ≥ 75 years (aRR=5.4, CI: 3.8-7.8) vs. 50-59 years (Table 1). Adults aged ≥ 50 years with the following individual chronic conditions had higher RSV hospitalization rates compared to those without the conditions: chronic kidney disease (aRR=6.1), COPD (aRR=4.9), severe obesity (aRR=4.0), asthma (aRR=3.2), diabetes (aRR=2.5), current smoking (aRR=2.1), and non-severe obesity (aRR=1.6; Figure 2). RSV hospitalization rates among adults aged ≥ 50 years with each chronic condition were highest in the oldest age groups (Figure 3).Figure 2.Adjusted rate ratios1 comparing respiratory syncytial virus (RSV) hospitalization rates among community-dwelling adults aged ≥50 years with and without chronic medical conditions—RSV Hospitalization Surveillance Network (RSV-NET), October 2017–April 2018Abbreviations: aRR: adjusted rate ratio; BMI: body mass index (kg/m2), COPD: chronic obstructive pulmonary disease; SI: simulation interval
1 aRR and 95% Monte Carlo CIs were estimated using Poisson regression and Monte Carlo simulation, after adjusting for age group (50-59 years, 60-74 years, ≥75 years), sex, and race and ethnicity group (non-Hispanic White, non-Hispanic Black, and other).

Conclusion
In community-dwelling adults aged ≥50 years, RSV hospitalization rates were higher among older adults and those with a history of select chronic conditions. These populations might benefit most from RSV vaccination when recommended for use.Figure 3.Respiratory syncytial virus (RSV) hospitalization rates1 among community-dwelling adults aged ≥50 years with chronic medical condition by age group—RSV Hospitalization Surveillance Network (RSV-NET), October 2017–April 2018Abbreviations: BMI: body mass index, COPD: chronic obstructive pulmonary disease
1 Rates of laboratory-confirmed RSV hospitalization account for under-detection of RSV infection among hospitalized adults and sensitivity of diagnostic tests. Rates are of community-dwelling adults and exclude residents of nursing homes and long-term care facilities. Rates are not adjusted for sex or race and ethnicity group.

Disclosures
All Authors: No reported disclosures