The predictive value of the hospital frailty risk score for 28-day mortality in older critically ill patients with acute ischemic stroke

OBJECTIVE: This study aimed to validate the predictive value of the Hospital Frailty Risk Score (HFRS) for 28-day mortality risk in older patients with acute ischemic stroke (AIS) admitted to the intensive care unit (ICU). METHODS: A retrospective cohort analysis was conducted using the Medical Information Mart for Intensive Care IV database (MIMIC-IV v3.1), including 1,702 older patients (aged ≥ 65 years) with AIS admitted to ICU. Restricted cubic spline (RCS) and piecewise Cox regression analyses were employed to explore the association between HFRS and 28-day mortality in older critically ill AIS patients. The predictive performance of HFRS was compared with the Sequential Organ Failure Assessment (SOFA) score, Charlson Comorbidity Index (CCI), and Glasgow Coma Scale (GCS) using receiver operating characteristic (ROC) curves. Based on the frailty risk stratification assessed by the HFRS, patients were divided into low-risk, intermediate-risk, and high-risk groups, and Kaplan-Meier survival curves with log-rank tests were generated to assess mortality trends. Multivariable Cox regression models were utilized to evaluate the independent association between HFRS and 28-day mortality. Subgroup analyses were performed to assess heterogeneity in outcomes by age, sex, and comorbidities. RESULTS: A nonlinear relationship was observed between HFRS and 28-day mortality in older critically ill patients with AIS, characterized by a threshold effect with an inflection point at 10.5. Below this threshold, each 1-unit increase in HFRS was associated with a 19% higher mortality risk (adjusted hazard ratio [HR] = 1.19, 95% confidence interval [CI]:1.13-1.26). Above the threshold, the incremental risk increase attenuated significantly (adjusted HR = 1.08, 95% CI:1.06-1.10). HFRS demonstrated superior predictive accuracy compared to other clinical scores, as evidenced by a higher area under the receiver operating characteristic curve (AUC = 70.6% vs. Sequential Organ Failure Assessment [SOFA]: 65.5%, Charlson Comorbidity Index [CCI]: 60.4%, Glasgow Coma Scale [GCS]: 68.6%). After adjusting for multiple covariates, multivariable Cox regression analysis demonstrated that individuals in the high risk group had an approximately 4.3-fold higher mortality risk compared to those in the low risk group (adjusted HR = 4.28, 95% CI:2.62-7.00; P < 0.001). CONCLUSION: HFRS shows a nonlinear correlation with short-term mortality in older critically ill AIS patients, outperforming SOFA, GCS, and CCI in predictive utility. As a reliable tool for assessing 28-day mortality risk, HFRS highlights the need for tailored intervention strategies based on frailty severity thresholds.