Two-Hour Improvement of Patients in the National Institute of Neurological Disorders and Stroke Trials and Prediction of Final Outcome

BACKGROUND AND PURPOSE: Ongoing clinical trials are using early response to intravenous tissue-type plasminogen activator (tPA) to stratify patients into endovascular therapies. Little is known about the likelihood of early recovery and its correlation with final stroke outcome. METHODS: We analyzed the National Institute of Neurological Disorders and Stroke tPA dataset for patients with early improvement (EI), a change of ≥4, or score 0 on the 2-hour National Institutes of Health Stroke Scale (NIHSS) to predict good 90-day outcome. We adjusted for multiple confounders and divided the patients by baseline NIHSS score 0 to 10, 11 to 20, >20, and stroke type to analyze if EI predicted good outcome across stroke severities and types. We analyzed different EI thresholds to identify the best level of NIHSS change to predict good 90-day outcome using a receiver-operator characteristic curve. RESULTS: In total, 183 of 624 (29.3%) patients had EI, 112 of 312 (35.9%) in the tPA group had EI, and 71 of 312 (22.7%) in the placebo group had EI (P<0.0001). Smokers (P=0.012) and patients treated in <90 minutes (P=0.008) were more likely to have EI; diabetic patients (P=0.023) were less likely to show EI. The baseline NIHSS (mean±SD) of patients with EI was 16.1±6.5 versus 14.3±7.4 (P=0.001). A 90-day modified Rankin Scale score of 0 to 1 was achieved in 68 of 112 (60.7%) tPA-treated patient with EI and 65 of 200 (32.5%) without (placebo groups 30 of 71 42.3% versus 53/241 22.0%). The adjusted odds ratio for good outcome was 1.71 (95% confidence interval CI, 1.1-2.6; P=0.011) for tPA treatment and 7.69 (95% CI, 4.63-12.76; P<0.0001) for early improvement. EI predicted good outcome in patients with cardioembolic (13.6; 95% CI, 3.6-51.5) and small vessel (6.98; 95% CI, 2.86-17.03), but not large vessel stroke (1.82; 95% CI, 0.38-8.59). The receiver-operator characteristic curve showed that a threshold of 4 on the NIHSS for prediction of good outcome had a sensitivity of 84% and 36% specificity. CONCLUSIONS: Early improvement was more common in tPA-treated patients and was associated with good 90-day outcome. Whereas 32.5% of nonresponders after tPA had a good 90-day outcome, the use of EI to predict stroke outcome shows value.