Table 1:

Demographic data

	Responders	Nonresponders	P Value
Age (mean) (yr)	61.5 (11.4)	59.3 (8.4)	.65^{^a}
Sex (No.) (%)			.34^{^b}
Male	21 (36)	1 (17)
Female	37 (64)	5 (83)
Presenting symptoms (No.) (%)			.58^{^b}
Radiculopathy	27 (47)	2 (33)
Axial back pain	4 (6)	0 (0)
Both	27 (47)	4 (67)

↵a P value based on the 2-sample t test of the difference between means.
↵b P value based on a χ² test of the difference in proportions.