Table 3.
Performance indices for the clinical prediction rule
| Performance index | Derivation cohort (n=9838) |
Validation cohort (n=5091) |
Internal validation* | |
| Mean (SD) | 95% CI | |||
| R2 | 0.024 | 0.018 | 0.025 (0.002) | 0.024 to 0.025 |
| Brier scores | 0.026 | 0.026 | 0.026 (0.001) | 0.025 to 0.026 |
| AUC | 0.76 (0.73 to 0.79)† | 0.73 (0.68 to 0.77)† | 0.76 (0.01) | 0.71 to 0.80 |
| Discrimination slope | 0.033 | 0.029 | 0.034 (0.004) | 0.033 to 0.035 |
| Calibration (p value) | 0.605 | 0.311 | 0.224 (0.208) | 0.100 to 0.995 |
| Calibration in the large (p value) | <0.001 | <0.001 | 0.028 (0.005) | 0.024 to 0.032 |
| Sensitivity (%) | 70.8 | 69.6 | 70.7 (2.7) | 65.5 to 76.1 |
| Specificity (%) | 67.8 | 66.8 | 67.8 (0.5) | 66.9 to 68.8 |
| Accuracy rate (%) | 67.9 | 66.9 | 67.8 (0.5) | 67.0 to 68.8 |
| Positive predictive value (%) | 5.8 | 5.5 | 5.8 (0.4) | 5.0 to 6.7 |
| Negative predictive value (%) | 98.8 | 98.7 | 98.8 (0.1) | 98.6 to 99.1 |
| Positive likelihood ratio | 2.20 | 2.10 | 2.19 (0.09) | 2.02 to 2.37 |
| Negative likelihood ratio | 0.43 | 0.46 | 0.43 (0.04) | 0.35 to 0.51 |
*1000bootstrap samples were generated by using resampling with replacement, and averages of these samples were presented to demonstrate the validity of the prediction rule.
†AUC (95% CI).
AUC, area under the receiver operating characteristic curve.