Table 3.

Factors associated with aggressive behaviours among all samples: results of a multivariate binary Firth logistic regression model

Variables	Model 1	Model 2	Model 3	Model 4
	OR (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
Age (years)
11–13	Reference	Reference	Reference	Reference
14–16	0.54 (0.34 to 0.88)	0.54 (0.33 to 0.87)	0.51 (0.31 to 0.83)	0.54 (0.34 to 0.88)
Gender
Boys	Reference	Reference	Reference	Reference
Girls	0.43 (0.27 to 0.70)	0.48 (0.29 to 0.77)	0.45 (0.28 to 0.73)	0.43 (0.27 to 0.70)
No of close friends
0–3	Reference	Reference	Reference	Reference
4–6	1.09 (0.62 to 1.90)	1.08 (0.62 to 1.90)	1.10 (0.63 to 1.94)	1.12 (0.64 to 1.95)
≥7	1.56 (0.90 to 2.68)	1.42 (0.83 to 2.44)	1.46 (0.85 to 2.52)	1.57 (0.91 to 2.71)
Perceived care from the primary caregiver
Lower	Reference	Reference	Reference	Reference
Higher	0.58 (0.35 to 0.94)	0.57 (0.35 to 0.93)	0.58 (0.35 to 0.95)	0.56 (0.35 to 0.92)
Only child
Yes	Reference	Reference	Reference	Reference
No	1.62 (0.99 to 2.68)	1.62 (0.98 to 2.65)	1.66 (1.01 to 2.75)	1.56 (0.95 to 2.57)
Neighbours caring for each other
Never or seldom	Reference	Reference	Reference	Reference
Sometimes	0.65 (0.38 to 1.11)	0.69 (0.41 to 1.18)	0.66 (0.39 to 1.12)	0.66 (0.39 to 1.12)
Always	0.46 (0.25 to 0.83)	0.45 (0.25 to 0.82)	0.43 (0.23 to 0.78)	0.45 (0.25 to 0.82)
Being bullied within 6 months
No	Reference	Reference	Reference	Reference
Yes	7.83 (4.44 to 13.80)	8.23 (4.67 to 14.50)	8.15 (4.62 to 14.39)	8.46 (4.81 to 14.88)
Impulsivity
Lowest tertile	Reference	Reference	Reference	Reference
Middle tertile	2.02 (0.99 to 4.11)	1.04 (0.55 to 1.99)	1.26 (0.67 to 2.37)	1.29 (0.68 to 2.45)
Highest tertile	3.23 (1.70 to 6.16)	1.99 (1.12 to 3.54)	3.07 (1.72 to 5.50)	2.04 (1.11 to 3.72)

The impulsivity in the models 1, 2, 3 and 4 refers to the total, attentional, motor and non-planning impulsivity, respectively.