2.3. Statistical Analysis
NRI
REGRESSION
Categorical variables were expressed as percentages, and differences among the variables were evaluated. Continuous variables were expressed using median and interquartile values. A prognostic nomogram for KTSCC was then established according to the variables screened using Cox regression. The concordance index (C-index) and time-dependent area under the receiver operating characteristic curve (AUC) were used to test the discrimination performance between the predicted value from this model and the actual value. Quantitative evaluation indicators such as net reclassification improvement (NRI) and integrated discrimination improvement (IDI) index were also used to evaluate whether the predictive ability of the model was improved over that of previous models in a more comprehensive and multilevel manner [SPSS Statistics software (version 27.0, Chicago, IL, USA) and R software (version 4.0.1; 