. Author manuscript; available in PMC: 2016 Nov 1.

Published in final edited form as: Anesth Analg. 2015 Nov;121(5):1336–1343. doi: 10.1213/ANE.0000000000000576

Table 3.

Initial multivariate model using Cox regression (χ² = 83.7, p < 0.001).^b

Variable^a	Hazard Ratio	95% Confidence Interval	P
Age (Years)	1.03	1.01, 1.05	<0.001*
Male	1.12	0.87, 1.45	0.38
Cognitive Impairment	0.98	0.75, 1.27	0.87
ASA Score	1.63	1.31, 2.02	<0.001*
Erythrocytes Transfused (units)	0.97	0.91, 1.04	0.38
Length of Stay in ICU (days)	1.08	1.04, 1.12	<0.001*
Delirium	1.20	0.93, 1.54	0.16

ASA = American Society of Anesthesiologists physical status score; ICU = intensive care unit.

Significant differences are indicated by an asterisk.

Since they were more informative, the duration of ICU stay and number of units of erythrocytes transfused were used rather than the corresponding categorical variables indicating ICU admission or erythrocyte transfusion.

Likelihood ratio tests were performed comparing the current model with one where the eliminated variables from Table 2 were incorporated one at a time in the model of the current table without achieving significance (depression, p = 0.95; time until surgery, p = 0.18; use of regional anesthesia, p = 0.40).