Table 3. Performance Measures With 95% CI in Derivation Cohort (N = 781) and Validation Cohort (n = 3260)^a.

Measure	Ordinal mRS	Functional independence (mRS 0-2)	Survival (mRS 0-5)
Internal validation
C statistic	0.84 (0.84-0.85)	0.92 (0.91-0.92)	0.87 (0.85-0.88)
External validation
C statistic	0.84 (0.83 to 0.84)	0.91 (0.90 to 0.92)	0.89 (0.88 to 0.90)
Calibration intercept	NA	0.61 (0.50 to 0.74)	−0.25 (−0.37 to −0.13)
Calibration slope	NA	0.98 (0.92 to 1.05)	0.86 (0.80 to 0.94)

Abbreviations: mRS, modified Rankin Scale; NA, not applicable.

^a The C statistic is a measure for the ability to distinguish between patients with a low and high probability of good outcome. It can vary between 0.5 for a noninformative model and 1 for a perfectly discriminating model. The calibration intercept reflects the calibration-in-the-large, indicating whether predicted probabilities are systematically too low or too high, and should ideally be equal to 0. The calibration slope reflects the strength of the predictors and should ideally be equal to 1.