Introduction: Predicting outcomes of acute stroke patients initially presenting with mild neurologic deficits is important in making decision for thrombolytic therapy. Previous researches with a small sample size have failed to find specific items of NIH Stroke Scale or clinical syndromes to be predictive of functional outcome.
Hypothesis: We hypothesized that certain items of the NIH Stroke Scale or their combinations would be independently associated with unfavorable functional outcome after mild stroke
Methods: Using a multicenter stroke registry database, we identified patients with acute ischemic stroke who presented within 4.5 hours of symptom onset and had initial NIH Stroke Scale scores ≤ 5. Functional outcomes at three months after the stroke were classified as favorable (modified Rankin Scale score [mRS] 0 to 1) or unfavorable (mRS 2-6). The individual NIH Stroke Scale items were dichotomized as absent (0) or present (≥1) for the analysis. The NIH Stroke Scale items and the total score were tested for predicting the outcomes in multivariable models adjusting for demographics and clinical characteristics. Area under the ROC curve (AUC) was used to assess the performance of multivariable models.
Results: Among 2,209 patients who met the eligible criteria, 588 patients (26.6%) exhibited unfavorable functional outcome (mRS 2-6) at three months. The most frequently present items were item 10 (dysarthria, 37.5%), item 4 (facial palsy, 21.1%), item 8 (sensory, 15.0%), and items indicating limb paralysis. Among 15 items of NIH Stroke Scale, all items except for item 8 (sensory) and item 11 (extinction) were significantly associated with unfavorable functional outcomes in bivariate analysis (P <0.05), and many of them remained significant in multivariable analyses. In multivariable analyses, the model including the total NIH Stroke Scale scores exhibited similar AUC (0.759; 95% CI, 0.740 -0.776; P=0.75 for pairwise comparison) compared to the model with all NIH Stroke Scale items (0.758; 0.739 - 0.775) in predicting functional outcomes after the stroke.
Conclusions: Simply using the total score was as effective as using all NIH Stroke Scale items in predicting outcomes of patients presented with mild stroke symptom.