Combination of 24-Hour and 7-Day Relative Neurological Improvement Strongly Predicts 90-Day Functional Outcome of Endovascular Stroke Therapy

Background and Purpose Early judgment of long-term prognosis is the key to making medical decisions in acute anterior circulation large-vessel occlusion stroke (LVOS) after endovascular treatment (EVT). We aimed to investigate the relationship between the combination of 24-hour and 7-day relative neurological improvement (RNI) and 90-day functional outcome. Methods We selected the target population from a multicenter ischemic stroke registry. The National Institutes of Health Stroke Scale (NIHSS) scores at baseline, 24 hours, and 7 days were collected. RNI was calculated by the following equation: (baseline NIHSS − 24-hour/7-day NIHSS)/baseline NIHSS × 100%. A modified Rankin Scale score of 0-2 at 90 days was defined as a favorable outcome. Multivariable logistic regression analysis was used to evaluate the relationship between RNI and 90-day outcome. Receiver operator characteristic curve analysis was performed to identify the predictive power and cutoff point of RNI for functional outcome. Findings A total of 568 patients were enrolled. Both 24-hour and 7-day RNI were independent predictors of 90-day outcome. The best cutoff points of 24-hour and 7-day RNI were 28% and 42%, respectively. Compared with those with 24-hour RNI of less than 28% and 7-day RNI of less than 42%, patients with 24-hour RNI of 28% or greater and 7-day RNI of 42% or greater had a 39.595-fold (95% confidence interval 22.388-70.026) increased probability of achieving 90-day favorable outcome. Conclusions The combination of 24-hour and 7-day RNI very strongly predicts 90-day functional outcome in patients with acute anterior circulation LVOS who received EVT, and it can be used as an early accurate surrogate of long-term outcome.