Table 4.

ROC Analyses for a Subset of Questionnaire and Demographic Data

Number of Items	Threshold	Sensitivity	Specificity	PPV %	NPV %	LR+	AUC	SE	95% CI	P
12	5	0.80	0.57	46	86	1.86	0.73	0.028	0.67–0.78	<.001
11	4	0.84	0.51	45	77	1.71	0.72	0.03	0.65–0.77	<.001
10	4	0.81	0.57	54	77	1.88	0.71	0.028	0.65–0.76	<.001

Note: PPV is the positive predictive—true positive/(true positive+ false positives); NPV is the negative predictive value—true negative/(true negative +false negative). The NPV is very high for all these measures, ie, a negative score really is likely to be negative. The PPV is relatively low (above threshold is 1/3 chance of being a genuine positive).