Association Between Premorbid Frailty Status and Functional Independence in Acute Ischemic Stroke Patients Following Endovascular Treatment in the Late Window.

Purpose: Although the predictive role of cerebral tissue impairment has been extensively investigated in acute ischemic stroke (AIS) patients undergoing endovascular treatment (EVT) in the late window, the impact of peripheral organs on clinical outcomes in these patients remains largely unknown. Therefore, we aimed to explore whether frailty, a reflection of the patient's physical status based on peripheral organ health at admission, could be associated with outcomes among AIS patients treated by EVT in the late window of 6-24 hours from stroke onset.

Patients and methods: This was a post-hoc analysis of our RESCUE-BT trial, with findings validated in an external cohort. The 5-factor modified frailty index (mFI-5), a scale of five factors that could reflect premorbid physical conditions, was applied to estimate frailty status. The primary outcome was functional independence, defined as a 90-day modified Rankin Scale (mRS) score of 0-2.

Results: There were 755 patients included in this study. After identifying the cut-off value of mFI-5 by the marginal effects approach, patients were divided into the frail group (mFI-5≥2) and the non-frail group (mFI-5<2). In multivariable analysis, frailty significantly reduced the likelihood of functional independence (aOR 0.37, 95% CI 0.21-0.65, P<0.001). Similar results were detected in the novel cohort constructed with propensity score matching (aOR 0.44, 95% CI 0.22-0.85, P=0.015) and in the external validation cohort (aOR 0.38, 95% CI 0.16-0.89, P=0.028). Moreover, frailty significantly improved the predictive performance of traditional predictors with an AUC of 0.77 (P=0.036 by DeLong's test).

Conclusion: This study demonstrated that frailty according to the mFI-5 index was inversely associated with functional independence among AIS patients receiving EVT in the late window.