Table 7. Sensitivity, specificity, and likelihood ratio of the Pittsburgh Sleep Quality Index (PSQI) at each cut-off score.

Cut-off score	Sensitivity (%)	Specificity (%)	+LR	-LR
≥1	100.0	0.0	1.00
>1	100.0	3.7	1.04	0.00
>2	100.0	14.8	1.17	0.00
>3	95.0	18.5	1.17	0.27
>4	90.0	33.3	1.35	0.30
>5	80.0	74.1	3.09	0.27
>6	75.0	88.9	6.75	0.28
>7	55.0	92.6	7.43	0.49
>9	45.0	92.6	6.08	0.59
>10	40.0	100.0		0.60
>11	30.0	100.0		0.70
>12	25.0	100.0		0.75
>13	10.0	100.0		0.90
>14	5.0	100.0		0.95
>15	0.0	100.0		1.00

+LR: likelihood ratio for a positive result; -LR: likelihood ratio for a negative result