Table 1.

Baseline characteristics by young and older adults who had no prior substance use treatment history

	Unmatched (N=817)			Matched (N=282)
	Young adults	Older adults	p value	Young adults	Older adults	p value
	(N=146)	(N=671)		(N=141)	(N=141)
Demographics
Age at treatment entry, mean (SD)	20.9 (2.5)	39.4 (9.2)	<0.0001	20.9 (2.4)	36.6 (7.2)	<0.0001
Female (%)	43.2	38.5	0.2919	41.8	41.8	1.0000
Race/ethnicity (%)			0.0546			1.0000
White	72.2	73.6		73.8	73.8
African American	6.3	12.1		6.4	6.4
Hispanic	13.2	9.1		13.5	13.5
Other	8.3	5.3		6.4	6.4
Education (%)			<0.0001			0.1594
Less than high school	24.8	11.3		24.3	17.0
High school grad.	52.4	45.7		53.6	52.5
Some college or more	22.8	43.0		22.1	30.5
Married (%)	15.8	48.4	<0.0001	16.3	48.9	<0.0001
Employed (%)	50.7	65.9	0.0006	51.1	61.0	0.0930
Income>=40K (%)	33.8	38.5	0.2979	35.1	38.1	0.6005
Substance use severity
Type of dependence (%)			<0.0001			0.9769
Alcohol only	15.1	38.0		15.6	15.6
Drug only	53.4	30.6		53.2	51.1
Both	21.9	16.2		21.3	23.4
No dependence	9.6	15.2		9.9	9.9
Alcohol ASI, mean (SD)	0.3 (0.3)	0.4 (0.3)	<0.0001	0.3 (0.3)	0.3 (0.3)	0.4611
Drug ASI, mean (SD)	0.2 (0.1)	0.1 (0.1)	<0.0001	0.2 (0.1)	0.2 (0.1)	0.8446
Age of first substance use (%)			<0.0001			0.0359
Under 15	69.0	47.5		68.6	56.4
>15	31.0	52.5		31.4	43.6
Years till first treatment (%)			<0.0001			<0.0001
0–9	66.9	2.1		67.1	2.1
>10	33.1	97.9		32.9	97.9
Project (%)			0.0292			0.3392
DHS	54.8	44.9		56.7	51.1
ICS	45.2	55.1		43.3	48.9

Note: DHS = Day Hospital Study; ICS = Integrated Care Study. ASI= Addiction Severity Index. SD = Standard Deviation.