Development and validation of the nomogram
REGRESSION
All patients obtained between 2010 and 2018 were randomized to training set (70%) and validation set (30%) for nomogram development and internal validation. Independent risk factors for patients in the training set were identified using both univariate and multivariate Cox proportional regression models. A nomogram was established based on the results of the multivariate Cox regression analysis to predict CSS at 3-, 5-, and 8-years in non-surgical treated elderly PC patients. In addition, we calibrated the nomogram for 3-, 5-, and 8-years using 1000 autonomous samples. The consistency index (c-index) and the area under the subject operating characteristic curve (AUC) were used to test the accuracy and discrimination of the model.