Redefining Early Neurological Improvement After Reperfusion Therapy in Stroke

Abstract Background and Purpose: Early neurologic improvement (ENI) in patients treated with alteplase has been shown to correlate with functional outcome. However, the definition of ENI remains controversial and has varied across studies. We hypothesized that ENI defined as a percentage change in the National Institute of Health Stroke Scale (NIHSS) score (percent change NIHSS score) at 24-hours would better correlate with favorable outcomes at 3 months than ENI defined as the change in NIHSS score (delta NIHSS score) at 24 hours. Methods: Retrospective analysis of prospectively collected single-center quality improvement data was performed of all acute ischemic stroke (AIS) patients treated with alteplase. We examined delta NIHSS score and percent change NIHSS score in unadjusted and adjusted logistic regression models as predictors of a favorable outcome at 3 months (defined as mRS 0-1). Results: Among 586 patients who met the inclusion criteria, 194 (33.1%) had a favorable outcome at 3 months. In fully adjusted models, both delta NIHSS score (OR per point decrease 1.27; 95% confidence interval [CI] 1.19-1.36) and percent change NIHSS score (OR per 10 percent decrease 1.17; 95% CI 1.12-1.22) were associated with favorable functional outcome at 3 months. Receiver operating characteristic (ROC) curve comparison showed that the area under the ROC curve for percent change NIHSS score (.755) was greater than delta NIHSS score (.613) or admission NIHSS (.694). Conclusions: Percentage change in NIHSS score may be a better surrogate marker of ENI and functional outcome in AIS patients after receiving acute thrombolytic therapy. More studies are needed to confirm our findings.