Risk factors associated with hospital admission, clinical progression and 90-day mortality in adults with respiratory syncytial virus infection

BACKGROUND: Respiratory syncytial virus has traditionally been associated with childhood illness, but it is increasingly recognised as a cause of severe disease in adults, particularly older people and those with chronic comorbidities. Despite its growing clinical relevance, evidence describing outcomes and predictors of disease severity in adults remains relatively limited. AIM: To identify factors associated with hospital admission, clinical severity and 90-day mortality in adults with respiratory syncytial virus infection. METHODS: A single-centre observational cohort study was conducted including 340 adults with polymerase chain reaction-confirmed respiratory syncytial virus infection between October 2023 and September 2024. Clinical, demographic and care-related variables were analysed using multivariable logistic regression and ordinal regression models. Clinical severity was assessed using an ordinal composite outcome including non-hospitalisation, hospital admission, intensive care unit admission and death. RESULTS: Of the 340 patients, 172 (50.6%) required hospital admission and 39 (11.5%) died within 90 days. Age 65 years or older, diabetes mellitus, immunosuppression, institutionalisation and chronic heart disease were independently associated with hospital admission. Age 65 years or older and chronic kidney disease were the strongest predictors of 90-day mortality. Ordinal regression analysis showed that these factors were consistently associated with increasing clinical severity. CONCLUSION: Adults with respiratory syncytial virus infection experience substantial morbidity and mortality, particularly those who are older, have chronic comorbidities or are socially vulnerable. These findings support early risk stratification and may assist critical care and interprofessional teams in identifying patients who require closer monitoring and timely escalation of care.