Table 2.

Univariate regression analysis assessing factors associated with surgical site infection.

	Univariate
Variable	OR (95%CI)	P
Age	1.03 (0.98–1.09)	.23
Female gender	1.79 (0.42–7.71)	.43
Previous spine surgery	3.24 (0.61–17.25)	.17
Body mass index	0.98 (0.86–1.12)	.78
Smoking	1.44 (0.17–12.59)	.74
Diabetes mellites	1.56 (0.36–6.75)	.55
Hypertension	5.62 (1.29–24.47)	.02
Preoperative hemoglobin level	0.68 (0.48–0.98)	.04
Preoperative white blood cell count	0.99 (0.87–1.14)	.98
Preoperative partial thromboplastin time	1.07 (1.04–1.11)	<.001
Preoperative creatinine level	1.04 (1.02–1.06)	<.001
Preoperative urea level	1.24 (1.02–1.50)	<.03
ASA class
I	1 Ref
II–III	2.25 (0.26–19.09)	.50
IV–V	26.0 (1.16–583.46)	.04
Duration of the procedure (min)	1.01 (1.01–1.02)	.01
Length of hospital stay before surgery (d)	1.17 (1.05–1.31)	.004
Postoperative hospital stays (d)	1.05 (1.02–1.09)	.006
Blood transfusion	23.3 (4.43–122.73)	<.001
Prophylactic antibiotics	0.24 (0.05–1.23)	.09
Use of drain	4.16 (0.82–21.16)	.09

ASA = American Society of Anesthesia, CI = confidence interval, OR = odds ratio.