Kaplan-Meier curves for 90-day recurrence-free survival and 90-day survival for Causative Classification of Stroke (CCS) (A and D), Trial of Org 10172 in Acute Stroke Treatment (TOAST) (B and E), and ASCO (A for atherosclerosis, S for small-vessel disease, C for cardiac source, and O for other cause) (C and F), showing that both outcomes vary by etiologic subtypes (log-rank test; P < .001 for all systems). The CCS system demonstrates better separation in Kaplan-Meier curves for recurrence-free survival compared with TOAST and ASCO (χ2, 53.2 for CCS, 25.1 for TOAST, and 32.7 for ASCO). CE indicates cardiac embolism; LAA, large-artery atherosclerosis; and SAO, small-artery occlusion.