Burden of Respiratory Syncytial Virus Infection in Children and Older Patients Hospitalized with Asthma: A Seven-Year Longitudinal Population-Based Study in Spain

(1) Background: To describe hospitalizations due to respiratory syncytial virus (RSV) infection among children and elderly patients with asthma. (2) Methods: We used a nationwide discharge database to select patients with asthma aged 0 to 15 years and ≥65 years admitted to Spanish hospitals from 2016 to 2022. (3) Results: We identified 49,086 children and 471,947 elderly patients hospitalized with asthma (3.52% and 0.51%, respectively, with RSV). The proportion of RSV increased over time in children with asthma (from 1.44% to 7.4%, <i>p</i> < 0.001) and in elderly individuals (from 0.17% to 1.01%, <i>p</i> < 0.001). Among children with RSV infection, the presence of influenza (OR 3.65; 95% CI 1.46-9.1) and pneumonia (OR 1.85; 95% CI 1.02-3.55) increased the risk of poor outcome. The presence of RSV was associated with severity in these patients, defined by use of mechanical ventilation and/or admission to the intensive care unit (OR 1.44; 95% CI 1.11-1.86). In elderly patients with RSV infection, older age, congestive heart failure, COVID-19, and pneumonia increased the risk of in-hospital mortality (IHM). However, RSV infection was not associated with IHM (OR 0.88; 95% CI 0.68-1.15) in these patients. (4) Conclusion: Our results highlight the impact of RSV infection in children and elderly patients hospitalized with asthma. Strategies to improve surveillance, prophylaxis, and management of RSV infection should be evaluated.