Table 4.

Logistic regression to determine the additional predictive value of postoperative pain and opioid use with respect to incident delirium on the second postoperative day.

Variables in addition to ICU Admission and Dementia	Overall χ2	Overall Area under ROC. curve**	P (Overall)	Dementia*	P Dementia	ICU Admission*	P ICU Admission	Additional variable*	P (Additional Variable)
None	37.9	0.74	<0.001	5.86 (3.04,11.31)	<0.001	2.71 (1.33,5.53)	0.006	NA	NA
Pain-POD1	25.2	0.73	<0.001	4.34 (2.03, 9.28)	<0.001	2.78 (1.26, 6.11)	0.011	0.90 (0.77, 1.06)	0.203
Pain-POD2	25.0	0.75	<0.001	4.25 (1.98, 9.12)	<0.001	2.19 (0.98, 4.93)	0.056	0.89 (0.74, 1.07)	0.220
Opioid-POD1	38.0	0.74	<0.001	6.00 (3.07, 11.74)	<0.001	2.76 (1.34, 5.68)	0.006	1.27 (0.35, 4.68)	0.711
Opioid-POD2	37.8	0.75	<0.001	5.70 (2.92, 11.15)	<0.001	2.58 (1.26, 5.27)	0.009	0.63 (0.11, 3.49)	0.591

^*Odds ratio (95% confidence interval)

^**Area under receiver operating characteristic (ROC) curve (range 0.5–1.0, equivalent to the C-statistic) for predictions of logistic model.

NA = not applicable; POD = postoperative day.