Functional Outcomes and Symptomatic Intracranial Hemorrhage After Endovascular Treatment in Acute Vertebrobasilar Artery Occlusions: External Validation of Prediction Models

Background Vertebrobasilar artery occlusion (VBAO) is a severe type of stroke. Multiple prediction models for outcome and symptomatic intracranial hemorrhage (sICH) of patients with acute ischemic stroke treated with endovascular treatment have been developed to improve patient management, but few are based on VBAO. This study aimed to provide an overview of published models to predict functional outcome and sICH as well as to validate their ability in patients with acute VBAO treated with endovascular treatment. Methods We performed a systematic search to identify models either developed or validated to predict functional outcomes or sICH after endovascular treatment. Models were externally validated in the Posterior Circulation Ischemic Stroke Registry (PERSIST) study (n = 2422). Outcome measures included the modified Rankin Scale (mRS) score at 90 days and sICH. Model performance was evaluated with discrimination (c‐statistic) and calibration (slope and intercept). Results A total of 65 models were included in overview. The most frequently used predictors were baseline National Institutes of Health Stroke Scale score (n = 57), age (n = 45), and glucose (n = 32). In the external validation cohort, 777 of 2353 patients (33.0%) achieved mRS score 0–2 at 90 days, 1061 of 2353 patients (45.1%) patients achieved mRS score 0–3 at 90 days, and sICH occurred in 170 of 2422 patients (7.0%). Finally, 27 models were included in external validation. For functional outcome models focusing on mRS score 0–2/3–6, discrimination ranged from 0.63 to 0.66 and best calibrated model was SC (Stroke Checkerboard) (intercept, −0.13 95% CI, −0.27 to 0.01; slope, 0.92 95% CI, 0.67–1.17). For functional outcome models focusing on mRS score 0–3/4–6, discrimination ranged from 0.64 to 0.74 and best calibrated model was modified Houston Intra‐Arterial Therapy 2 (mHIAT2) (intercept, −0.12 95% CI, −0.31 to 0.07; slope, 0.85 95% CI, 0.65–1.04). For sICH models, discrimination ranged from 0.53 to 0.83 and best calibrated model was Thrombolysis in Cerebral Infarction score, Alberta Stroke Program Early CT Score, and glucose (TAG) (intercept, 0.13 95% CI, −0.25 to 0.51; slope, 0.93 95% CI, 0.63–1.23). Conclusions The currently published models are inadequate for predicting functional outcomes and sICH in patients with acute VBAO undergoing endovascular treatment and, therefore, there is a need for more effective models specifically developed for VBAO conditions.