Fig. 4

Calibration plots of the predictive model. A Calibration plot in the development set. B Calibration plot in the validation set. The x-axis is the predicted probability of hyperkalemia. The y-axis is the observed hyperkalemia. The diagonal dotted line represents a perfect prediction by an ideal model. The solid line represents the performance of the nomogram. It represents a better prediction that a solid line is close to a diagonal dotted line. The figure shows that the prediction model has a good predictive ability