Table 1.

Preoperative Characteristics of All Patients

	Use of midazolam	No midazolam	p-value	Standardized Difference*
n (%)	909 (71.8%)	357 (28.2%)
Age (yr), mean ± SD	72.2 ± 5.6	74.5 ± 6.6	< 0.01	0.38
Female, n (%)	474 (52.2%)	169(47.3%)	0.12	−0.10
Charlson, mean ± SD	0.9 ± 1.5	1.2 ± 1.4	< 0.01	0.17
ASA Classification, n (%)
I – II	497 (54.7%)	191 (53.5%)	0.71	−0.02
III – V	412 (45.3%)	166 (46.5%)
TICS score, mean ± SD	33.8 ± 3.5	32.7 ± 4.2	< 0.01	−0.28
Preoperative use of benzodiazepine, n (%)	112 (12.3%)	30 (8.4%)	0.05	0.13
Surgical site, n (%)
Hip	221(24.3%)	77 (21.6%)	< 0.01	0.20
Knee	204 (22.4%)	55(15.4%)
Spine	324 (35.6%)	137(36.4%)
Other	160 (17.6%)	88 (24.7%)
Year, n (%)
< 2010	449 (66.9%)	222 (33.1%)	< 0.01	0.26
≥ 2010	460 (77.3%)	135 (22.7%)

Abbreviations: ASA, American Society of Anesthesiology; SD, standard deviation; TICS, Telephone Interview for Cognitive Status.

^*Standardized Difference: the difference in means or proportions divided by the pooled standard deviation