Frailty Assessed by Administrative Tools and Mortality in Patients With Pneumonia Admitted to the Hospital and ICU: a Population-based Data-linkage Study

Background: The ideal method of identifying frailty is uncertain, and data on long-term outcomes is relatively limited. We examined frailty indices derived from population-scale linked data on Intensive Care Unit (ICU) and hospitalised non-ICU patients with pneumonia to elucidate the influence of frailty on mortality. Methods: Longitudinal cohort study between 2010-2018 using population-scale anonymised data linkage of healthcare records for adults admitted to hospital with pneumonia in Wales. Primary outcome was in-patient mortality. Age, hospital frailty risk score (HFRS), electronic frailty index (eFI), Charlson comorbidity index (CCI), and social deprivation index were entered in the multivariate regression models. Results: Of the 107,188 patients, mean (SD) age was 72.6 (16.6) years, 50% were men. The two frailty indices and the comorbidity index had an increased risk of mortality for individuals with an ICU admission. Advancing age, increased frailty and comorbidity affected short- and long-term mortality. For predicting inpatient deaths, the CCI and HFRS based models were similar, however for longer term outcomes the CCI based model was superior. Discussion: Frailty and comorbidity are significant risk factors for patients admitted to hospital with pneumonia. Frailty and comorbidity scores based on administrative data have only moderate ability to predict outcome.