Clinical phenotypes and outcomes associated with respiratory syncytial virus infection in critically ill patients: a retrospective multicentre cohort study in Great Paris area hospitals, 2017-2023.

Background: Respiratory syncytial virus (RSV) is one of the deadliest respiratory viruses. There is a need to better identify prognostic factors in RSV-infected patients, particularly those requiring intensive care unit (ICU) admission, with a focus on immunosuppressed patients.

Methods: Multicenter, retrospective cohort study of RSV-infected adults hospitalized in 17 ICUs in the Great Paris area between 08/01/2017 and 05/01/2023. The primary endpoint was all cause day 30 mortality. Supervised and unsupervised analyses were performed.

Results: During the study period, 474 patients with RSV infection were admitted. Patients were predominantly male (56%), were 65±17-years old, had frequent cardiovascular and respiratory comorbidities and 34% were immunosuppressed. Day 30 mortality was 14%. Besides age >65 years and acute respiratory failure, immunosuppression was associated with day 30 mortality in multivariable logistic regression analysis (adjusted odds ratio=2.10 95% confidence interval [1.14;3.80]; p=0.035). Unsupervised cluster analysis identified three groups of patients: one cluster (17%) included only immunosuppressed patients and had the highest day 30 mortality rate (21%); the second cluster (43%) included older patients (median age 71 years) with a high prevalence of cardiovascular and respiratory comorbidities and an intermediate mortality rate (14%); the last cluster (37%) included younger patients (median age 57 years) with the lowest mortality rate (9%).

Conclusion: One third of patients admitted to the ICU with RSV infection were immunosuppressed. Both supervised and unsupervised methods identified immunosuppression as being associated with day 30 mortality. The effect of anti-RSV therapies aimed at preventing ICU admission should be evaluated in this subgroup of patients.