**Figure 6.** **The machine learning models encompassing FN1 and POSTN to diagnose CRS.** (**A**) A nomogram was drawn to visualize the logistic regression model. (**B**) The confusion matrix showed the predictive performance of the logistic regression model. (**C**) The classification tree was established to diagnose CRS. (**D**) The confusion matrix of the classification tree model. (**E**) The mean decrease accuracy and mean decrease Gini of the features in the random forest model. (**F**) The confusion matrix exhibited that the random forest model could distinguish the CRS samples with high efficacy. Abbreviation: CRS: cardiorenal syndrome.