Premorbid frailty (mFI-5) and functional recovery after endovascular thrombectomy for acute ischemic stroke

Endovascular thrombectomy (EVT) is the standard treatment for acute ischemic stroke due to anterior-circulation large-vessel occlusion (LVO), yet outcomes remain heterogeneous. We evaluated whether premorbid frailty, measured by the modified Frailty Index-5 (mFI-5), predicts 90-day functional outcomes and whether its effect varies across treatment windows or anesthesia strategies.

In this retrospective cohort study, adults undergoing EVT (2015-2024) were included. Frailty was assessed using mFI-5. The primary outcome was functional independence at 90 days (mRS 0-2); the secondary outcome was in-hospital mortality. Multivariable logistic regression adjusted for age, sex, NIHSS, ASPECTS, reperfusion, anesthesia modality, and time to reperfusion. Sensitivity analyses included ordinal regression, subgroup analyses, interaction testing, and multiple imputation for missing outcomes.

Among 455 patients, 57.6% achieved functional independence at 90 days. Each 1-point increase in mFI-5 was associated with lower odds of functional independence (aOR 0.61, 95% CI 0.49-0.78) and higher in-hospital mortality (aOR 2.37, 95% CI 1.60-3.52). These associations were consistent across analytic approaches, anesthesia modalities, and reperfusion strata. Stratified analyses indicated a stronger association in the early EVT window (≤6 hours) compared with the late window (interaction p = 0.029). Intra-procedural hypotension was not independently associated with outcomes after adjustment.

Premorbid frailty was associated with poorer functional recovery and higher mortality after EVT. The association appeared stronger in the early treatment window and was not influenced by anesthesia or reperfusion status. Frailty assessment may complement existing prognostic factors in EVT.