Table 1.

Demographics and clinical characteristics of cases affected with a chronic tic disorder and of age- and sex- propensity matched controls

Variable	Cases (N=236)			Controls (N=518)
	Mean	SD	Range	Mean	SD	Range	df	t	p
Age in years	39.2	16.7	3–79	41.2	14.7	9–83	406	−1.56	0.12
SESa	4.46	1.49	1–7	4.39	1.49	1–7	703	0.62	0.55
Worst ever total YGTSS ratingb	12.4	7.88	1–30	0	0
Worst ever total Y-BOCS ratingc	11.1	10.5	0–36	4.05	7.5	0–40	599	9.36	<0.001
Total ADHD SNAP-IV symptom countd	3.87	4.98	0–18	1.43	3.16	0–18	752	8.11	<0.001
	N	%		N	%	OR	95% CI OR	χ2	Pe
Participants <18 years old	35	14.8		53	10.2	1.53	0.98–2.41	3.33	0.07
Male	110	46.6		257	49.6	1.13	0.83–1.53	0.59	0.48
Race white	222	94.1		498	96.2	0.64	0.32–1.28	1.61	0.14
Tourette’s disorderf	145	61.4		0	0
Chronic motor or vocal tic disorderf	91	38.6		0	0
OCD diagnosisf	88	37.3		68	13.2	4.02	2.78–5.80	59.3	<0.001
ADHD diagnosisf	44	18.6		20	4.0	6.04	3.46–10.5	48.8	<0.001

df, degrees of freedom; SES, socioeconomic status; YGTSS, Yale Global Tic Severity Scale (Leckman et al., 1989; Storch et al., 2005); OCD, obsessive-compulsive disorder; Y-BOCS, Yale–Brown Obsessive–Compulsive Scale (Goodman et al., 1989a, 1989b; Scahill et al., 1997); ADHD, attention–deficit/hyperactivity disorder; SNAP-IV, Swanson, Nolan and Pelham-IV rating scale (Bussing et al., 2008; Swanson, 1992; Swanson et al., 2001).

^aBased on parents’ education level (1= less than 7 years of schooling to 7= graduate/professional degree)

^bSum score of worst ever motor and phonic tics (range 0–30)

^cSum score of worst ever obsessions and compulsions (range 0–40)

^dNumber of items scored as “2=quite a bit” or ”3=very much” on the SNAP-IV (range 0–18)

^eComparisons were done using Pearson’s chi-square test with one degree of freedom

^fLife-time diagnosis based on the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV-TR (American Psychiatric Association, 2000)