Table 2.

Biostatistical methods to define PPV and Typhim Vi cut-off levels.

Criterion	AUC (95% CI)	Se	Sp	PosPV	NegPV	P-value	Youden index cut-off	Union index cut-off	Closest-topleft cut-off
PRE anti-PPV Ab	0.65 (0.51-0.80)	0.5476190	0.78	0.82	0.48	0.034	4.61	6.95	5.11
POST anti-PPV Ab	0.79 (0.69-0.90)	0.8095238	0.75	0.85	0.69	0.054	20.15	19.6	20.15
POST/PRE anti-PPV Ratio	0.56 (0.41-0.72)	0.7380952	0.47	0.72	0.51	0.369	3.31	1.14	3.31
PRE anti-Typhi Ab	0.68 (0.54-0.83)	0.6428571	0.69	0.79	0.51	0.013	6.30	6.30	6.30
POST anti-Typhi Ab	0.93 (0.87-0.99)	0.9047619	0.95	0.97	0.85	<0.001	28.55	44.4	28.55
POST/PRE anti-Typhi ratio	0.93 (0.87-0.99)	0.9047619	1.00	1.00	0.85	<0.001	5.11	5.94	5.11

AUC: area under the curve; Se: sensitivity; Sp: specificity; PosPV: positive predictive value; NegPV: negative predictive value.