Fig. 3From: Surrogate biomarkers of outcome for wake-up ischemic strokea Distribution of serum vitamin D levels quartiles for both IS patient groups. b ROC curve analysis to establish the sensitivity and specificity of serum vitamin D levels to predict wake-up IS risk. The cut-off point of vitamin D that optimally predicted a wake-up stroke was 9 ng/ml (area under curve 0.908, sensitivity 88%, specificity 75%, p < 0.0001)Back to article page