Predictive factors of functional independence after optimal reperfusion in anterior circulation ischaemic stroke with indication for intravenous thrombolysis plus mechanical thrombectomy

Background and purpose: Intravenous thrombolysis plus mechanical thrombectomy (IVT + MT) is the best current management of acute stroke due to large-vessel occlusion and results in optimal reperfusion for most patients. Nevertheless, some of these patients do not subsequently achieve functional independence. The aim was to identify baseline factors associated with 3-month independence after optimal reperfusion and to validate a prediction model.

Methods: All consecutive patients with intracranial anterior large-vessel occlusion, with indication for IVT + MT and achieving optimal reperfusion (defined as modified Treatment in Cerebral Ischaemia score 2b-3), from the THRACE trial and the ETIS registry, were included in order to identify a prediction model. The primary outcome was 3-month independence [modified Rankin Scale (mRS) score ≤ 2]. Multivariate inferences invoked forward logistic regression, multiple imputation and bootstrap resampling. Predictive performance was assessed by c-statistic. Model validation was conducted on patients from the ASTER trial.

Results: Amongst 139 patients (mean age 65.5 years; 54.3% female), predictors of 3-month mRS ≤ 2 (n = 82) were younger age [odds ratio 0.62 per 10-year increase; 95% confidence interval (CI) 0.53-0.72] and higher Alberta Stroke Program Early Computed Tomography Score (ASPECTS) (odds ratio 1.65 per 1-point increase; 95% CI 1.47-1.86) with c-statistic 0.77. Model validation (n = 104/181 patients with 3-month mRS ≤ 2) demonstrated a moderate discrimination (c-statistic 0.74; 95% CI 0.66-0.81) combining age and ASPECTS. The validation model was improved by the adjunction of three candidate variables that were found to be predictors. Addition of baseline National Institutes of Health Stroke Scale (NIHSS) score, history of vascular risk factor and onset-to-reperfusion time significantly improved discrimination (c-statistic 0.85; 95% CI 0.83-0.87).

Conclusions: After optimal reperfusion, younger age, higher ASPECTS, lower NIHSS score, shorter onset-to-reperfusion time and absence of vascular risk factor were predictive of independence and could help to guide patient management.