Treatment strategy, stroke severity, and functional outcomes in acute ischemic stroke: evidence of effect modification in a real-world cohort.

Objectives

To explore the association between treatment strategy and functional outcomes in acute ischemic stroke (AIS) and assess whether this association is modified by stroke severity and imaging findings.

Methods

We conducted a retrospective single-center cohort study of adults with AIS treated between March 2023 and September 2025 at a tertiary stroke center in Central Asia. Patients were categorized into intravenous thrombolysis, selective intra-arterial thrombolysis, or angiography without thrombolysis. The primary outcome was poor functional outcome, defined as modified Rankin Scale (mRS) score ≥ 3 at discharge. Multivariable logistic regression and interaction analyses were performed.

Results

A total of 247 patients were included, of whom 60.3% had poor functional outcomes. Outcomes differed significantly between treatment groups (p = 0.024), with favorable outcomes more common after intravenous thrombolysis than after selective intra-arterial thrombolysis or angiography without thrombolysis. In multivariable analysis, both selective intra-arterial thrombolysis (OR 2.23, 95% CI 1.04-4.78) and angiography without thrombolysis (OR 2.70, 95% CI 1.23-5.92) were associated with higher odds of poor outcome than intravenous thrombolysis. A significant interaction was observed between treatment strategy and admission NIHSS (Pinteraction < 0.001), whereas the interaction with MRI-confirmed ischemia was not significant (Pinteraction = 0.066). Admission NIHSS demonstrated modest predictive performance (AUC 0.65, 95% CI 0.56-0.74).

Discussion

In this exploratory observational cohort, treatment strategy was associated with functional outcome at discharge, and this association varied according to baseline stroke severity. Because treatment allocation was non-random and residual confounding cannot be excluded, these findings should be considered hypothesis-generating rather than causal evidence of treatment effectiveness.