Clinical burden of disease and demographics in older adults hospitalised with RSV infection in England: A retrospective cohort study

Introduction: Respiratory syncytial virus (RSV) causes significant disease in older and comorbid adults. Current UK vaccination recommendations restrict eligibility to adults ≥75-years, 65-74-years with chronic respiratory disease or immunosuppression, and those in care homes, but evidence on clinical burden in adults <75-years with comorbidities is limited. This study assessed patient characteristics, healthcare resource utilisation (HCRU), and mortality in adults hospitalised with RSV in England. Methods: Population-based retrospective cohort study using linked Clinical Practice Research Datalink Aurum and Hospital Episode Statistics. Adults ≥60-years hospitalised with RSV between October 2014-March 2019 were included. RSV episodes defined as 90-days post diagnosis. Case definitions were created using diagnosis codes related to confirmed RSV (RSV-specific) or acute lower respiratory tract infection where other causative pathogens were excluded (RSV-possible). All-cause HCRU (hospitalisations, critical care admissions, outpatient attendance, primary care consultations, and prescriptions) and case fatality rates were assessed. Results were stratified by age (60-74 and ≥75-years), case definitions (RSV-specific, RSV-possible) and comorbidity profiles (chronic respiratory disease, immunocompromised, cardiovascular disease). Results: A total of 97,712 hospitalised episodes in those aged ≥60-years were included in the analysis, where 785 (0.8%) were RSV-specific cases (n=338 aged 60-74-years, n=447 aged ≥75-years). In RSV-specific cases, median (IQR) cumulative length of stay (LoS) for those ≥75-years was 10.00 (6.00-22.00) days which was equivalent to or lower than each comorbidity sub-group in those aged 60-74-years, with longest LoS in those immunocompromised (11.50 [7.00-26.00] days). Critical care admissions were more often observed across comorbidity stratifications (13.85%-22.34%) compared to those ≥75-years (5.03%). All-cause and RSV-related case fatality rates for RSV-specific cases were highest among those ≥75-years (all-cause: 19.3%; RSV-related: 10.3%). Conclusion: HCRU within RSV episodes in those aged 60-74-years across comorbidity profiles was equal to or greater compared to those aged ≥75-years. These findings highlight the need to prioritise consideration of comorbidity groups that could benefit from RSV vaccination. Key words: Respiratory syncytial virus; vaccine; chronic obstructive pulmonary disease; diabetes mellitus; immunocompromised; asthma; chronic kidney disease; cardiovascular disease; healthcare resource utilisation.