. Author manuscript; available in PMC: 2012 Mar 15.

Published in final edited form as: Spine (Phila Pa 1976). 2011 Mar 15;36(6):474–480. doi: 10.1097/BRS.0b013e3181d41632

Table 1.

Demographic variables for the patients that met inclusion criteria and included in analyses and those meeting inclusion criteria but excluded (due to missing data) from analyses.

	Included	Excluded	t-test or χ² p value
N	701	656
Age (mean±SD)	45.91±9.58	45.72±9.86	.80
Gender (n, % male)	367 (52.4)	331 (51.3)	.60
Race (n, %)			<.001
Caucasian	390 (55.6)	290 (45.0)
Black	179 (25.5)	138 (21.4)
Hispanic	117 (16.7)	201 (31.2)
Other	15 (2.1)	16 (2.5)
LOD¹ (mean±SD)	17.72±16.68	17.89±20.15	.80

LOD is Length of Disability in Months