Table 1.

Descriptive statistics of sample by smoking status (N = 158)

Variable	Entire cohort (N = 158)	Smoking (N1 = 41)	Nonsmoking (N2 = 117)	p Value*
Age (years), mean (SD)	61	55.3 (8.6)	63.1 (11.7)	< 0.0001
Length of followup (months), mean (SD)	14.5	10.7 (6.0)	15.8 (14.1)	0.002
Levels fused, mean (SD)	4.2	4.1 (0.87)	4.2 (1.0)	0.3
Gender, number (%)				0.29
Males	93	27 (65.8)	66 (56.4)
Females	65	14 (34.2)	51 (43.6)
Diagnosis, number (%)				0.91
Stenosis	138	36 (87.8)	102 (87.2)
Other	20	5 (12.2)	15 (12.8)

* p Value from t-test and chi square or Fisher’s exact test