Table 3.

Internal Validity of Predictive Models for the Pittsburgh Sleep Quality Index ≥6 by Various Combinations of Predictors

Number of Predictors	Subgroups	SEN (%)	SPE (%)	PPV (%)	NPV (%)
Full model
8	Predictors: sleep quality, hypnotics use, sleep onset, lacking enthusiasm, sleep disruption, pain, sleepy activities, nightmare
	Low insomnia	62.7	90.7	65.3	89.7
	High insomnia	64.4	98.8	81.5	97.2
	High hypnotics	58.9	95.9	59.7	95.7
Reduced models
5	Predictors: sleep quality, hypnotics use, sleep onset, lacking enthusiasm, sleep disruption
	Low insomnia	63.9	90.0	64.2	89.9
	High insomnia	62.3	98.9	82.1	97.1
	High hypnotics	49.6	96.4	59.0	94.9
4	Predictors: sleep quality, hypnotics use, sleep onset, lacking enthusiasm
	Low insomnia	61.3	89.4	61.8	89.2
	High insomnia	55.5	99.3	86.2	96.6
	High hypnotics	60.6	94.6	53.8	95.9
3	Predictors: sleep quality, hypnotics use, sleep onset
	Low insomnia	49.8	92.1	64.0	86.8
	High insomnia	51.8	99.5	90.0	96.3
	High hypnotics	77.2	91.4	48.2	97.5

Abbreviations: SEN, sensitivity; SPE, specificity; PPV, positive predictive value; NPV, negative predictive value.