Table I.

Study sample and source population demographics

Characteristic	Study sample		Population
	N = 616		N = 6782
	n	%	n	%
Sex (female)	406	65.9	5048	74.4
Race
White	547	88.8	5765	85.0
Hispanic	41	6.7	632	9.3
Native American	16	2.6	154	2.3
African-American	10	1.6	182	2.7
Other	2	0.3	49	0.7
Diagnoses
Epilepsy	255	41.4	1188	17.5
Bipolar disorder	196	31.8	4401	64.9
Depression	99	16.1	1916	28.3
Migraine	112	18.2	1406	20.7
Neuropathic pain	17	2.8	137	2.0
Other pain	182	29.5	2303	34.0
Age (mean [SD], years)	35.6 [15.5]		34.37 [14.27]
Treatment length (mean [SD], months)	32.8 [4.2]		10.93 [12.19]