Table 1.

Comparison between the groups

	Total	Non-smokers	Smokers	P
Number of cases	58,304	45,952 (78.8%)	12,352 (21.2%)
Age (years)		62.0	53.6	<0.001*
Male (%)	46.2	45.4	49.3	<0.001*
Anemia (%)	18.2	19.4	13.8	<0.001*
Hypoalbuminemia (%)	2.0	1.9	2.2	0.022
Dependent functional status (%)	2.3	2.3	2.0
Comorbidities
Diabetes (%)	17.9	19.0	13.8	<0.001*
Hypertension (%)	57.2	59.7	47.8	<0.001*
COPD (%)	4.9	3.4	10.4	<0.001*
Heart failure (%)	0.2	0.2	0.3	0.661
Chronic steroid use (%)	4.1	4.4	3.1	<0.001*
Hemodialysis (%)	0.2	0.2	0.3	0.338
BMI	30.9	29.7	<0.001*
Operative time (mean hours)		3.6	3.5	<0.001*
ASA category of 3 or higher (%)	50.7	50.7	50.4	0.442
Average number of levels		1.6	1.5	<0.001*
Transfusions (%)	13.7	14.5	10.8	<0.001*
Complications (%)	6.7	6.9	6.0	<0.001*
Severe complications (%)	1.9	2.0	1.6	0.014*
Discharge to SNIF (%)	10.4	11.5	6.3	<0.001*
Length of stay (days)		3.8	3.5	<0.001*
Mortality (%)	0.2	0.2	0.2	0.809

*shows the P value is significant at p=.05