Table 1. Characteristics of Study Cohorts of Children with and without ASD.

Characteristic	ASD	no ASD	p-value
	N=7,901	N=79,010
Age -- in January 2010 (%)
1-2 years	0.5	0.5	--
3-4 years	10.2	10.2
5-7 years	22.6	22.6
8-11 years	29.1	29.1
12-14 years	21.1	21.1
15-17 years	16.6	16.6
Male sex (%)	82.3	82.3	--
Neighborhood SES: adults with any college (%)
0% - 43%	22.8	26.1	<0.0001
44% - 58%	23.5	24.4
59% - 72%	26.8	25.5
73% +	26.4	23.5
Neighborhood SES: median household income (%)
$0 - $44,000	21.3	24.5	<0.0001
$45,000 - $59,000	24.6	25.5
$60,000 - $77,000	26.3	25.1
$78,000 +	27.2	24.3
Other psychiatric diagnosis -- in 2009-10 (%)
ADD/ADHD	31.8	6.9	<0.0001
anxiety	16.7	3.1	<0.0001
disruptive disorders	13.4	2.4	<0.0001
depression	7.6	3.1	<0.0001
intellectual disabilities	5.6	0.1	<0.0001
other psychiatric signs/symptoms*	3.3	0.5	<0.0001
bipolar disorder	2.7	0.2	<0.0001
schizophrenia/psychoses	1.3	0.1	<0.0001
any non-ASD psychiatric dx	73.2	17.2	<0.0001
Service utilization -- in 2010
outpatient visits, any (%)	95.7	87.8	<0.0001
(mean no. of outpt visits)	(9.2)	(3.5)	<0 .0001
MH outpatient visits, any (%)	51.6	8.7	<0.0001
(mean no. of MH outpt visits)	(3.7)	(0.48)	<0 .0001
ED visits, any (%)	13.4	11.8	<0.001
Hospitalizations, any (%)	2.6	0.9	<0.0001
Non-psychiatric Rx, any (%)	63.7	58.7	<0.0001

Notes: Other psychiatric signs/symptoms included tics, Tourette's, enuresis, encopresis, and trichotillomania. Hospitalizations included both medical and psychiatric hospitalizations. P-values presented are from Chi-squared tests for percentage differences and Student's T tests for differences in means.