Associations of impulsivity, hyperactivity, and inattention with nonsuicidal self-injury and suicidal behavior: longitudinal cohort study following children at risk for neurodevelopmental disorders into mid-adolescence

Table 1 Participant characteristics including demographic and clinical information

	No NSSI or SB (n = 348)		NSSI and/or SB (n = 43)		Total (n = 391)
	n	%	n	%	n	%
Age at interview
9	16	4.6	3	7.0	19	4.9
12	332	95.4	40	93.0	372	95.1
Birthyear
1993	183	52.6	26	60.5	209	53.5
1994	125	35.9	12	27.9	137	35.0
1995	40	11.5	5	11.6	45	11.5
Sex
Female	136	39.1	30	69.8	166	42.5
Male	212	60.9	13	30.2	225	57.5
Screen status^a
Screen-positive NDD	168	48.3	24	55.8	192	49.1
Screen-positive comorbidity only^b	42	12.1	6	14.0	48	12.3
Screen-negative co- twin	138	39.7	13	30.2	151	38.6
Screen-positive disorder^a,c
ADHD	75	21.6	14	32.6	89	22.8
Learning disorder	66	19.0	8	18.6	74	18.9
ODD	35	10.1	10	23.3	45	11.5
DCD	32	9.2	5	11.6	37	9.5
OCD	34	9.8	3	7.0	37	9.5
Tic disorder	31	8.9	4	9.3	35	9.0
Autism spectrum disorder	23	6.7	3	7.0	26	6.7
Childhood self-harm^a,d	9	2.6	4	9.3	13	3.3
	Mean	SD	Mean	SD	Mean	SD
Other NDD factor^e	-0.02	1.01	0.2	0.91	0	1.0

Note. ADHD = Attention-Deficit/Hyperactivity Disorder; DCD = Developmental coordination disorder; NSSI = Nonsuicidal self-injury; NDD = Neurodevelopmental disorder; OCD = obsessive-compulsive disorder; ODD = Oppositional defiant disorder; SB = Suicidal behavior; SD = Standard deviation
^aAt age 9 or 12
^bOppositional defiant disorder, conduct disorder, obsessive-compulsive disorder, and/or eating disorder
^cMultiple screen-positive disorders were possible. In addition, 13 participants (3.3%) were screen-positive for eating disorders and 4 (1.0%) participants for conduct disorder
^dSelf-harm measured with a caregiver as respondent in the A-TAC through the item “Has he/she ever deliberately hurt him/herself?”. Both ‘yes, to some extent’ (0.5) and ‘yes’ (1) were considered presence of self-harm. In total, 36 (9.2%) participants had missing values on this item
^eStandardized factor score generated through factor analysis with the other neurodevelopmental disorder items as described in Methods section

ISSN: 1471-244X