Fig. 3.  Receiver operating characteristic (ROC) curve drawn using the simplified risk score. Development subsample, c-statistic for the area under the ROC curve (AUC) = 0.89 (95% confidence interval [CI], 0.83–0.93); validation subsample, c-statistic for the AUC = 0.84 (95% CI, 0.77–0.90). The simplified risk score was obtained by multiplying the logistic regression β coefficient by 10 and rounding off its value.