Validation of the Hospital Frailty Risk Score among older adults receiving mechanical ventilation

Abstract Background:Older adults are increasingly being admitted to intensive care units, with frailty recognized as a risk factor for worse outcomes. The Hospital Frailty Risk Score (HFRS) was developed for use in administrative databases of older adults, but it has not yet been well-validated for critically ill patients. The objective of this study was to validate the HFRS to predict prolonged hospitalization, in-hospital mortality, and 30-day emergency hospital readmissions in critically ill patients.Methods:We selected index hospitalizations of older adults (≥75 years old) receiving mechanical ventilation, using the United States Nationwide Readmissions Database from January 1, 2016 to November 30, 2018. Frailty risk was determined by the HFRS using International Classification of Diseases, Tenth Revision Clinical Modification (ICD-10-CM) codes, and further subcategorized into low (score <5), intermediate (score 5-15), and high (score >15) risk for frailty. We evaluated the HFRS to predict prolonged hospitalization, in-hospital mortality, and 30-day emergency hospital readmissions, using multivariable logistic regression after adjustment for patient and hospital characteristics. Model performance was assessed using the c-statistic, Brier score, and calibration plots.Results:Among the 649,330 weighted index hospitalizations in the cohort, 50.0% were female, the median (interquartile range [IQR]) age was 81 (78-86) years old, and the median (IQR) HFRS was 10.8 (7.7-14.5). Among the cohort, 9.5%, 68.3%, and 22.2% were subcategorized as low, intermediate, and high risk for frailty, respectively. After adjustment, patient hospitalizations with high frailty risk were associated with increased risks of prolonged hospitalization (adjusted odds ratio [aOR] 5.59 [95% confidence interval [CI] 5.24-5.97], c-statistic 0.694, Brier score 0.216) and 30-day emergency hospital readmissions (aOR 1.20 [95% CI 1.13-1.27], c-statistic 0.595, Brier score 0.162), compared to low frailty risks. Conversely, high frailty risk using the HFRS was inversely associated with in-hospital mortality (aOR 0.46 [95% CI 0.45-0.48], c-statistic 0.712, Brier score 0.214). Calibration plots demonstrated good calibration for the adjusted analyses.Conclusions:The HFRS is associated with prolonged hospitalization and 30-day readmission in older adults receiving mechanical ventilation. Further research is necessary to develop frailty scores that accurately and intuitively predict mortality in critically ill patients.