NIHSS-time score easily predicts outcomes in rt-PA patients: The SAMURAI rt-PA registry
BACKGROUND
We aimed to devise a scale comprising a simple multiplication of initial National Institutes of Health Stroke Scale (NIHSS) score and onset-to-treatment time (OTT) as a scale for predicting outcomes after recombinant tissue plasminogen activator (rt-PA) therapy.


METHODS
Data from rt-PA patients in 10 stroke centers in Japan were investigated. NIHSS-time score was calculated as initial NIHSS score×OTT.


RESULTS
Subjects comprised 526 patients. Median NIHSS score was 12 (7-18), and median OTT was 2.42 h (2.00-2.75 h). Median NIHSS-time score was 27.7 (16.9-41.7). Good (modified Rankin Scale [mRS] 0-1) and poor (mRS 4-6) outcome rates at 3months for patients with NIHSS-time scores ≤ 10 were 71.1% and 7.8%, compared to 54.7% and 16.5% for scores >10 and ≤ 20, 38.9% and 31.9% for scores >20 and ≤ 30, 25.0% and 44.6% for scores >30 and ≤ 40, and 17.4% and 61.8% for scores >40, respectively. Cut-off NIHSS-time scores to predict good and poor outcomes with 50% probability were defined as 20 and 40, respectively. Multivariate logistic regression analysis revealed NIHSS-time score as an independent predictor of good (odds ratio [OR], 0.587; 95% confidence interval [CI], 0.422-0.818, p=0.002) and poor (OR, 1.756; 95%CI, 1.227-2.514, p=0.002) outcomes after adjusting for age, sex, NIHSS score, OTT, Alberta Stroke Program Early CT Score, internal carotid artery occlusion, and glucose level.


CONCLUSIONS
NIHSS-time score predicts clinical outcomes in rt-PA patients.