3.3. Nomogram Creation and Evaluation
REGRESSION
We used the final results from the multivariate Cox regression to construct a nomogram (The next step was to evaluate the nomogram. The C-index in both the training (0.688) and validation (0.691) cohorts was better than that of the AJCC staging system (0.617 and 0.611). The AUC values for the 3-, 5-, and 8-year OS probabilities were 0.709, 0.723, and 0.742 in the training cohort and 0.716, 0.725, and 0.741 in the validation cohorts; the corresponding values for the AJCC staging system were 0.653, 0.644, 0.632 and 0.646, 0.621, 0.620, respectively. These findings indicated that the new model had better predictive power than the AJCC staging system (The NRI values for evaluating OS probability in the training cohort were 39.6% (95% CI = 34.04–49.16%) at 3 years, 47.0% (95% CI = 41.59–55.63%) at 5 years, and 56.3% (95% CI = 50.42–68.21%) at 8 years, and for the validation cohort were 45.17% (95% CI = 29.40–58.72%), 53.30% (95% CI = 40.93–63.84%), and 60.18% (95% CI = 48.54–72.97%), respectively. The IDI values for OS in the training and validation cohorts were 10.5% and 10.6%, respectively, at 3 years (
