Functional Outcomes in Basilar Artery Occlusion Stroke

Basilar artery occlusion (BAO) accounts for 6% to 10% of ischemic strokes and is associated with a higher mortality and morbidity than ischemic stroke in the anterior circulation. Intravenous thrombolysis is the mainstay of acute treatment, and intra-arterial therapy is currently being investigated in the BASICS trial (Basilar Artery International Cooperation Study). Despite intravenous thrombolysis and intra-arterial treatment, disability ensues in the majority of patients. Because medical decisions to pursue or withdraw ventilator support, tracheostomy, gastrostomy, long-term rehabilitation, and placement in skilled nursing facilities are often made in the first few days after BAO, early accurate prognostication tools can be clinically meaningful and can guide physicians and family members during decision making. Fairly good prognostic accuracy (area under the curve [AUC], 0.79–0.80) for long-term outcome in BAO patients can be achieved by incorporating clinical variables (admission National Institutes of Health stroke scale [NIHSS], age, hyperlipidemia, prodromal minor stroke, and time to treatment) and computed tomography imaging data available at the time of presentation. Severity of neurological deficits can be measured by the NIHSS at admission and has previously been identified to independently predict clinical outcomes in stroke patients. NIHSS often changes during the first 24 hours, and the relationship between the neurological examination and long-term functional outcome strengthens after the first few hours and then begins to plateau. Early neurological improvement may reflect recanalization of BAO, whereas failure of improvement or clinical decline may reflect persistent occlusion, substantial Background and Purpose—Accurate long-term outcome prognostication in basilar artery occlusion strokes may guide clinical management in the subacute stage. We determine the prognostic value of the follow-up neurological examination using the National Institutes of Health stroke scale (NIHSS) and identify 24to 48-hour NIHSS risk categories in basilar artery occlusion patients. Methods—Participants of an observational registry of radiologically confirmed acute basilar artery occlusion (BASICS [Basilar Artery International Cooperation Study]) with prospectively collected 24to 48-hour NIHSS and 1-month modified Rankin scale scores were included. Uniand multivariable modeling were performed to identify independent predictors of poor outcome. Predictive powers of baseline and 24to 48-hour NIHSS for poor outcome (modified Rankin scale, 4–6) and 1-month mortality were determined by receiver operating characteristic analyses. Classification and regression tree analysis was performed to identify risk groups. Results—Three hundred seventy-six of 619 BASICS participants were included, of whom 65.4% had poor outcome. In multivariable analyses, 24to 48-hour NIHSS (odds ratio=1.28 [1.21–1.35]), history of minor stroke (odds ratio=2.64 [1.04–6.74], time to treatment >6 hours (odds ratio=3.07 [1.35–6.99]), and age (odds ratio=1.02 [0.99–1.04]) were retained in the final model as predictors of poor outcome. Prognostic power of 24to 48-hour NIHSS was higher than baseline NIHSS for 1-month poor outcome (area under the curve, 0.92 versus 0.75) and mortality (area under the curve, 0.85 versus 0.72). Classification and regression tree analysis identified five 24to 48-hour NIHSS risk categories with poor outcome rates of 9.4% (NIHSS 0–4), 36% (NIHSS 5–11), 84.3% (NIHSS 12–22), 96.1% (NIHSS 23–27), and 100% (NIHSS≥28). Conclusions—Twenty-fourto 48-hour NIHSS accurately predicts 1-month poor outcome and mortality and represents a clinically valuable prognostic tool for the care of basilar artery occlusion patients. (Stroke. 2016;47:2534-2540. DOI: 10.1161/STROKEAHA.116.014567.)