Table 4.

Independent risk factors for major perioperative complications assessed by multivariable logistic regression. REF: control group for comparison.

(I) Independent risk factors for major perioperative complications:
Category	Variable	p value	Odds Ratio (OR)	95% Confidence Intervalfor OR (low, high)
Surgical procedure type	Anterior surgery only - 2–3 levels or fewer		(REF)
	Anterior surgery only - more than 3 levels	0.017	1.4	1.1	2.0
	Anterior and posterior together	<0.001	2.6	1.8	3.8
	Posterior only - up to 6 levels	<0.001	1.5	1.2	1.8
	Posterior only - greater than 6 levels	<0.001	2.3	1.8	3.0
Diagnosis group	Cervical Spondylosis/Stenosis/Disc		(REF)
	Disseminated tumor	0.037	1.6	1.0	2.5
	Solitary tumor (malignant or benign)	<0.001	4.0	2.6	6.0
	Cervical Fractures/Dislocations	<0.001	3.4	2.2	5.1
	Thoracolumbar Spondylosis/Stenosis/Disc	<0.001	1.4	1.2	1.8
	Spinal Fractures/Dislocations, Others, Unspecified	0.018	1.7	1.1	2.6
	Infection	<0.001	3.2	1.9	5.3
	Scoliosis	<0.001	1.8	1.4	2.5
	Others	0.014	1.4	1.1	1.9
	Thoracolumbar Fractures/Dislocations	0.059	1.7	1.0	2.8
	Spondylolisthesis	0.085	1.3	1.0	1.8
Age	18–40	0.85	1.0	0.7	1.5
	41–50		(REF)
	51–60	<0.001	1.7	1.3	2.3
	61–70	<0.001	2.0	1.5	2.6
	>70	<0.001	2.4	1.8	3.2
BMI	<18.5	0.44	0.8	0.4	1.4
	18.5–24.9		(REF)
	25.0–29.9	0.60	1.0	0.8	1.1
	30.0–34.9	0.18	0.9	0.7	1.1
	35.0–39.9	0.80	1.0	0.8	1.2
	≥40	0.019	1.4	1.1	1.8
Race	White		(REF)
	Black	<0.001	1.6	1.3	2.0
	Other or Unknown	0.49	0.9	0.7	1.2
Current smoker within one year	Yes vs. No	0.028	1.2	1.0	1.4
>10% body weight loss in last 6 months	Yes vs. No	0.002	2.3	1.4	3.9
Steroid use for chronic condition	Yes vs No	0.004	1.5	1.1	1.9
Currently on dialysis (preop)	Yes vs No	0.002	2.7	1.4	5.2
ASA class	1–2 (No/Mild Disturb)		(REF)
	3 (Severe Disturb)	<0.001	1.5	1.3	1.7
	4–5 (Life Threat/Moribund)	<0.001	2.6	2.0	3.5
	Unknown	0.64	0.6	0.1	4.6
Preoperative WBC count (/mL)	< 12,000		(REF)
	≥ 12,000	0.012	1.4	1.1	1.8
	Unknown	0.45	0.6	0.2	2.2
Preoperative hematocrit (%)	≤ 24	0.31	0.6	0.2	1.6
	> 24 to ≤ 35		(REF)
	> 35	0.007	0.8	0.6	0.9
	Unknown	0.59	0.8	0.3	1.9
Preoperative platelet count (/mL)	> 50,000		(REF)
	≤ 50,000	0.035	3.2	1.1	9.5
	Unknown	0.48	1.5	0.5	5.0

(II) Risk factors that were also adjusted for, but were considered “non-significant” with the p value less than 0.05:
Category	Variable	p value	Hazard Ratio (HR)	95% HR Confidence Interval (low, high)
Gender	Male vs. Female	0.17	1.1	1.0	1.3
Dyspnea	Yes vs. No	0.074	1.2	1.0	1.6
History of severe COPD	Yes vs. No	0.69	0.9	0.7	1.3
Congestive heart failure in 30 days before surgery	Yes vs. No	0.28	1.5	0.7	3.0
Hypertension requiring medication	Yes vs. No	0.91	1.0	0.8	1.2
Insulin-dependent Diabetes	Yes vs. No	0.68	1.1	0.8	1.4
Bleeding disorders	Yes vs. No	0.094	1.4	0.9	2.0
Preoperative serum sodium (mmol/L)	≤ 130	0.98	1.0	0.6	1.7
	> 130		(REF)
	Unknown	0.58	1.2	0.7	2.0
Preoperative BUN (mg/dL)	≤ 40		(REF)
	> 40	0.72	0.9	0.5	1.6
	Unknown	0.17	1.3	0.9	2.0
Preoperative serum creatinine (mg/dL)	< 1.5		(REF)
	≥ 1.5	0.17	1.3	0.9	1.8
	Unknown	0.20	0.7	0.4	1.2
Preoperative INR	< 1.5		(REF)
	≥ 1.5	0.14	1.6	0.9	2.8
	Unknown	0.37	0.9	0.8	1.1