Tommaso Morelli, Martha Purcell, J Panaguiton, Rachel Patel, Sharon Weinberg, George Hulston, Hans Siy-yap, Emma A Davies, Anluan Keating, Ida Saidy, Anna Freeman, Karl J. Staples, Pedro Rodrigues, Abigail Jones, Alex Allen, Aruna T Bansal, Stefan J. Marciniak, Neil J Greening, Michael G Crooks, Philip Mitchelmore, Salman H Siddiqui, James Myerson, Matthew Pavitt, Cyrus Daneshvar, James D. Chalmers, Paul Hong Lee, Tom Lewis, TW Clark, Sarah Denny, Dexter Wiseman, Huw Ellis, Tom Wilkinson
BACKGROUND: Respiratory syncytial virus (RSV) causes substantial winter pressure on adult services. In the UK, RSV vaccination currently targets adults aged ≥75 years and care home residents; it remains uncertain whether this age criterion alone meaningfully discriminates risk of poor outcome among adults hospitalised with RSV. METHODS: We pooled three UK hospital cohorts (one prospective, two retrospective) of adults admitted with acute respiratory infection (ARI) and PCR-confirmed RSV. The primary outcome was intensive care unit/high dependency unit (ICU/HDU) admission or all-cause mortality within 60 days. Prespecified predictors (age, sex and comorbidities) entered a least absolute shrinkage and selection operator (LASSO) penalised logistic regression; selected variables were refitted using standard logistic regression. Discrimination, calibration and decision-analytic performance were assessed using 1000-bootstrap internal validation and decision-curve analysis. RESULTS: Among 334 adults, 37 (11.1%) experienced the primary outcome. An age-only rule mirroring current UK vaccine age-eligibility (≥75 years) demonstrated only modest discrimination (optimism-adjusted area under the receiver operating characteristic curve (AUC) 0.58, 95% CI 0.48 to 0.65) and a compressed distribution of predicted risks. A four-predictor model-including age, COPD, active/previous cancer and dementia-achieved higher discrimination AUC (0.77 (0.69 to 0.85)), a wider spread of predicted risks and the greatest net benefit across clinically plausible escalation thresholds (5-20%). CONCLUSIONS: In adults hospitalised with RSV-associated ARI, simple age-based heuristics-including the UK ≥75-year threshold-showed only modest ability to discriminate risk of ICU/HDU admission/60-day mortality once hospitalised. Comorbidity-inclusive approaches may provide more informative hospital-level risk stratification and warrant evaluation in future RSV vaccine-effectiveness and outcome studies. Any application requires external validation, more systematic RSV testing and comparison with physiology-based scores in larger, vaccinated cohorts.