Table 6. Sensitivity and specificity for SASE-CHI with ESCA as a criterion (n = 1152).

Cut-off points	Sensitivity (%)	Specificity (%)	Youden's index	PPV (%)	NPV (%)
56.5	100	34.8	0.348	82.15	100
57.5	97.9	38.3	0.362	82.64	85.87
58.5	97.9	42.8	0.407	83.70	87.17
59.5	97.9	48.7	0.466	85.13	88.55
60.5	97.9	55.6	0.535	86.87	89.82
61.5	97.5	61.1	0.586	88.26	96.07
62.5	97.5	67.8	0.653	90.08	96.44
63.5	96.8	74.8	0.716	92.01	88.63
64.5	94.3	79.3	0.736	93.18	82.26
65.5	91.5	83.4	0.749	94.30	76.58
66.5	88.0	86.8	0.748	95.24	70.68
67.5	83.0	91.0	0.740	96.51	64.08
68.5	78.8	93.1	0.719	86.59	59.41
69.5	62.2	93.8	0.560	96.78	71.28
70.5	45.2	95.2	0.404	96.58	36.67
71.5	34.3	95.9	0.302	96.16	59.34
72.5	18.0	98.2	0.162	96.77	39.92
73.5	11.7	98.6	0.103	96.16	27.13
74.5	4.9	99.2	0.041	96.05	25.80
75.5	2.8	99.5	0.023	94.38	25.44
76.5	2.1	99.5	0.016	96.25	25.31
78.0	2.1	100	0.021	100	25.40

SASE-CHI: the Chinese version of Self-care Ability Scale for the Elderly.

ESCA: the Exercise of Self-care Agency scale