Table 4.
Discrimination and Calibration of Models in Derivation and Validation Cohorts (Primary Outcome)
| Model and risk score performance metrics | Derivation cohort | Validation cohort |
|---|---|---|
| Model based performance | ||
| Brier scorea | 0.293 | 0.294 |
| Nam–D’Agostino testb | χ2 = 7.5930, P = 0.3031 | χ2 = 7.6178, P = 0.3407 |
| Harrell’s C statistic (95% CI)c | 0.810 (0.805-0.816) | 0.812 (0.804-0.820) |
| Sensitivity (95% CI) | 0.442 (0.439-0.446) | 0.443 (0.438-0.447) |
| Specificity (95% CI) | 0.954 (0.953-0.955) | 0.954 (0.953-0.956) |
| Positive predictive value (95% CI) | 0.825 (0.822-0.828) | 0.825 (0.821-0.830) |
| Negative predictive value (95% CI) | 0.777 (0.776-0.778) | 0.777 (0.776-0.779) |
| Accuracy (95% CI) | 0.786 (0.784-0.787) | 0.786 (0.784-0.788) |
| Risk score performance | ||
| Sensitivity (95% CI) | 0.209 (0.207-0.212) | 0.211 (0.207-0.215) |
| Specificity (95% CI) | 0.928 (0.927-0.929) | 0.929 (0.928-0.931) |
| Positive predictive value (95% CI) | 0.590 (0.585-0.595) | 0.597 (0.590-0.604) |
| Negative predictive value (95% CI) | 0.705 (0.704-0.705) | 0.705 (0.704-0.706) |
| Accuracy (95% CI) | 0.692 (0.690-0.693) | 0.693 (0.690-0.695) |
CI: confidence interval.
a
Measures both discrimination and calibration; lower values indicate higher accuracy. bA modification of Hosmer–Lemeshow test suited for survival data; measure of calibration that is specific to censored survival data (lower χ2 and higher P values) indicate better calibration. cA measure of discrimination for which higher values indicate better discrimination.