Prediction of long-term outcome by percent improvement after the first day of thrombolytic treatment in stroke patients

Background: We investigated a method for assessing early improvement and predictive factors of early and late outcomes in patients receiving thrombolytic therapy. Methods: A total of 160 consecutive patients who received thrombolytic therapy were included in the study. Using National Institutes of Health Stroke Scale (NIHSS) scores, percent improvement [(baseline NIHSS score - 24-hour NIHSS score) / baseline NIHSS score × 100] was calculated and compared with delta (baseline NIHSS score - 24-hour NIHSS score) and with major neurological improvement (MNI, NIHSS score of 0-1 or ≥ 8 point improvement at 24 h) by receiver operating characteristic (ROC) curve analysis. Finally, we investigated the independent predictors of improvement at 24 h after the thrombolytic therapy and of favorable 3-month outcome (modified Rankin scale score 0-2). Results: By pairwise comparison of ROC curves, percent improvement was stronger than delta (p = 0.004) and MNI (p < 0.001) in predicting long-term outcome. First day improvement (FDI), defined as greater than 20% improvement, was a strong predictor of favorable 3-month outcome (OR 12.55, 95% CI 5.41-29.10). Recanalization (OR 3.30, 95% CI 1.28-8.45), absence of carotid T occlusion (OR 0.09, 95% CI 0.02-0.42) and hemorrhagic transformation (OR 0.25, 95% CI 0.09-0.73) were independent predictors of FDI. Independent predictors of favorable 3-month outcome were FDI, current smoking, absence of carotid T occlusion and hemorrhagic transformation. Conclusions: Percent improvement at 24 h after thrombolytic therapy is a useful surrogate marker for predicting the long-term outcome. Our findings highlight the importance of early stroke management.