Simple clinical predictors of stroke outcome based on National Institutes of Health Stroke Scale score during 1-h recombinant tissue-type plasminogen activator infusion

Background and purpose An index for predictors of stroke outcome was determined based on the National Institutes of Health Stroke Scale (NIHSS) scores during 1-h intravenous administration of recombinant tissue-type plasminogen activator (rt-PA). Methods Stroke patients with baseline NIHSS score ≥8 and occlusion at the internal carotid or middle cerebral arteries (ICA, MCA) were retrospectively studied from a prospective single-center registry. NIHSS scores and inverse change from baseline scores (ΔNIHSS) were assessed at 30 min and 1 h after rt-PA infusion. Patients were divided into two groups according to arterial occlusion sites: group P, ICA or proximal M1; and group D, distal M1 or M2. A modified Rankin Scale score of 2–6 at 3 months was defined as an unfavorable outcome. Results In all 108 patients, the cutoff NIHSS score predicting unfavorable outcome was ≥12 and cutoff ΔNIHSS scores were ≤2 at both 30 min and 1 h. In group P (n = 36), the cutoff NIHSS score was ≥14 at both 30 min and 1 h and cutoff ΔNIHSS scores were ≤1 at 30 min and ≤2 at 1 h. Unfavorable outcome was seen in all patients with NIHSS1 h ≥ 14, ΔNIHSS30 min ≤ 1 and ΔNIHSS1 h ≤ 2. In group D (n = 72), the cutoff NIHSS scores were ≥12 at both 30 min and 1 h, and cutoff ΔNIHSS scores were ≤2 at 30 min and ≤7 at 1 h; 90% of patients with unfavorable outcome showed ΔNIHSS1 h ≤ 7. Conclusion NIHSS and ΔNIHSS during 1-h rt-PA infusion seemed predictive of 3-month outcome when the site of arterial occlusion was identified prior to rt-PA.