To identify optimal threshold values for predicting malnutrition, receiver-operating characteristic (ROC) curve analysis was performed for MNA scores. The area under the ROC curve (AUC) was also evaluated. An AUC value of 0.5 indicates that the variable performs no better than chance, whereas a value of 1.0 indicates perfect discrimination. A larger AUC represents a greater reliability and discrimination of the scoring system. Cut-off values can be set depending on the purpose for which the scales are used. For screening purposes, a high sensitivity and a high negative-predictive value are required, whereas diagnosis requires a high specificity and a high-positive predictive value. The best Youden index (sensitivity + specificity - 1) was used to determine the best cut-off point. The Youden index is used to compare the proportion of cases correctly classified. The higher the Youden index, the more accurate the prediction (higher true positives and true negatives, and fewer false positives and false negatives) at the cut-off point.