Hospital Admissions for Respiratory Syncytial Virus (RSV) Among Elderly: A Retrospective Study From an Italian Southern Region During Years 2018-2023.

INTRODUCTION: Respiratory syncytial virus (RSV) is one of the most common causes of acute respiratory infections in both children and adults over 60. RSV can cause severe lower respiratory tract infections in older adults, leading to an increase of morbidity and mortality. The aim of this study was to assess the incidence of hospitalizations due to RSV infections in the Abruzzo region of Italy among patients aged over 60 years. METHODS: A retrospective study was performed in the Abruzzo region, evaluating all hospitalizations performed during years 2018-2023. Age- and gender-standardized hospitalization rates for RSV were calculated. Patients' comorbidities and hospitalization-related outcomes were also assessed. RESULTS: During 2018-2023, 42 RSV-coded hospitalizations were identified among adults aged ≥ 60 years. An additional RSV-attributable burden was estimated by applying a literature-derived attributable fraction to hospitalizations for unspecified viral bronchiolitis and pneumonia, resulting in an estimated total of 67 RSV-attributable admissions. Annual age- and sex-standardized RSV-coded hospitalization rates showed substantial year-to-year variability. Poisson regression with correction for overdispersion identified no statistically significant temporal trend during the study period (IRR per calendar year 1.08, 95% CI 0.86-1.34; p = 0.516). Among patients with RSV-coded admissions, the median length of stay was 11 days (IQR 6-18), and four patients (9.52%) died during hospitalization. CONCLUSIONS: RSV was associated with a measurable burden of hospitalization among older adults in Abruzzo. However, substantial year-to-year variability and the small number of RSV-coded admissions warrant cautious interpretation of temporal patterns. No statistically significant temporal trend was identified during the study period.