Table 2. Internal validation by cross-validation.

	Sensitivity	Specificity	PPV	NPV	Accuracy
CV1	0.81	0.87	0.96	0.56	0.82
CV2	0.89	0.27	0.78	0.46	0.73
CV3	0.89	0.38	0.81	0.54	0.77
average	0.86	0.51	0.85	0.52	0.77

PPV; Positive Predictive Value, NPV; Negative Predictive Value, CV; Cross-Validation