Table 3.

Characteristics of infected patients classified as instrumented and non-instrumented cases

	Instrumented cases (n = 6)	Non-instrumented cases (n = 2)	p value
Gender (n, %)
Male	2 (33)	2 (100)	0.214
Female	4 (67)	0 (0)
Age at surgery (years) (range)	68.5 (66–83)	57.5 (52–63)	0.067
Body mass index (kg/m2) (range)	24.0 (20.4–28.1)	21.4 (16.6–26.1)	0.617
Serum albumin (g/dl) (range)	4.4 (4.1–4.7)	3.9 (3.5–4.3)	0.309
Red blood cells (×104 μl) (range)	457 (414–496)	400 (397–403)	0.067
Smoking (n, %)	0 (0)	0 (0)	N/A
Steroid use (n, %)	0 (0)	0 (0)	N/A
Hypertension (n, %)	2 (33)	1 (50)	0.893
Diabetes mellitus (n, %)	4 (67)	0 (0)	0.214
Malignant tumor (n, %)	1 (17)	0 (0)	0.750
Rheumatoid arthritis (n, %)	0 (0)	0 (0)
Obstructive lung disease (n, %)	0 (0)	1 (50)	0.250
Coronary artery disease (n, %)	1 (17)	0 (0)	0.750
Diagnosis (n, %)
Degenerative disease	5 (83)	2 (100)	0.750
Spine injury	0 (0)	0 (0)
Spinal tumor	1 (17)	0 (0)
Region (n, %)
Cervical	0 (0)	0 (0)	0.536
Thoracic	2 (33)	0 (0)
Lumbar, ilium	4 (67)	2 (100)
Surgical approach (n, %)
Anterior	0 (0)	0 (0)	N/A
Posterior	6 (100)	2 (100)
Revision (n, %)	0 (0)	1 (50)	0.250
Number of decompression or fusion levels (n, %)
1–2	1 (17)	2 (100)	0.108
3	2 (33)	0 (0)
4–6	3 (50)	0 (0)
≥7	0 (0)	0 (0)
Estimated blood loss (g) (range)	235 (50–1014)	250.5 (5–496)	0.868
Duration of operation (min) (range)	230 (150–335)	251.5 (78–425)	0.888
Transfusion (n, %)	5 (83)	1 (50)	0.464
Packed red blood cells (n, %)	3 (50)	1 (50)	0.786
Autologous blood (n, %)	2 (33)	0 (0)	0.536

Data are presented as n (%) or median (range)