A laboratory-based frailty index predicts mortality in ischemic stroke with carotid artery stenosis: a retrospective analysis from the MIMIC-IV database.

Ischemic stroke (IS), particularly due to carotid artery stenosis (CAS), is a major global contributor to mortality and disability. Frailty, characterized by systemic physiological decline and reduced homeostatic reserves, has emerged as a powerful prognostic marker across a wide range of diseases. We aimed to evaluate the prognostic utility of a laboratory-based frailty index (FI-Lab) in patients with IS secondary to CAS (IS-CAS), focusing on short- and long-term mortality. Data were extracted from the MIMIC-IV database. FI-Lab was calculated using 33 routine tests within 24 h of ICU admission. Patients were stratified into quartiles based on FI-Lab scores. Cox proportional hazards models, restricted cubic splines, Kaplan-Meier curves, and subgroup analyses were applied. Among 1,869 IS-CAS patients, higher FI-Lab scores were independently associated with increased 30-day and 1-year mortality (p for trend < 0.001). The highest quartile had a significantly elevated hazard ratio compared to the lowest. Survival curves and RCS analyses supported a linear association. Subgroup analysis showed consistent trends, especially in patients not receiving mechanical ventilation. FI-Lab is a robust predictor of both short- and long-term mortality in IS-CAS. It holds promise for individualized risk stratification and could aid clinical decision-making in stroke management.