Table 2.

Associations between socio-demographic factors and IA^a,b

	Males		Females
	%	ORu (95 % CI)	%	ORu (95 % CI)
School grade
Secondary 1	12.23	1.00	9.30	1.00
Secondary 2	17.83	1.56 (1.25 ~ 1.95)	13.88	1.57 (1.20 ~ 2.07)
Secondary 3	19.69	1.76 (1.42 ~ 2.18)*	14.61	1.67 (1.28 ~ 2.18)
Secondary 4	20.75	1.88 (1.51 ~ 2.34)**	17.67	2.09 (1.61 ~ 2.71)**
Father’s education level
Junior secondary school or below	21.76	1.00	15.34	1.00
Senior secondary school or matriculation	17.14	0.74 (0.62 ~ 0.89)**	13.81	0.88 (0.72 ~ 1.08)
University or college or above	12.34	0.51 (0.40 ~ 0.64)**	12.69	0.80 (0.61 ~ 1.06)
Missing	17.99	0.79 (0.64 ~ 0.98)*	13.30	0.85 (0.65 ~ 1.10)
Mother’s education level
Junior secondary school or below	23.09	1.00	15.52	1.00
Senior secondary school or matriculation	16.01	0.64 (0.54 ~ 0.76)**	13.63	0.86 (0.71 ~ 1.05)
University or college or above	12.68	0.48 (0.38 ~ 0.62)**	10.72	0.65 (0.47 ~ 0.90)*
Missing	17.28	0.70 (0.56 ~ 0.86)**	14.45	0.92 (0.71 ~ 1.19)
Living arrangement with parents
Living with both parents	16.46	1.00	13.09	1.00
Living with the mother only	22.44	1.47 (1.16 ~ 1.85)**	18.58	1.52 (1.17 ~ 1.96)**
Living with the father only	30.82	2.26 (1.60 ~ 3.20)**	20.97	1.76 (1.13 ~ 2.74)*
Living with none of the parents	20.00	1.27 (0.83 ~ 1.95)	17.01	1.36 (0.88 ~ 2.11)
Missing	20.56	1.31 (0.82 ~ 2.12)	14.75	1.15 (0.56 ~ 2.35)
Father’s age	Not applicable	1.01 (0.99 ~ 1.02)	Not applicable	1.01 (0.99 ~ 1.02)
Whether born in HK/length of stay
Yes, born in HK	17.01	1.00	13.88	1.00
No, stayed in HK ≥7 years	20.74	1.28 (1.03 ~ 1.58)*	15.02	1.10 (0.86 ~ 1.40)
No, stayed in HK <7 years	19.93	1.21 (0.90 ~ 1.65)	13.37	0.96 (0.69 ~ 1.34)
No, don’t remember when came to HK	16.83	0.99 (0.58 ~ 1.67)	12.33	0.87 (0.43 ~ 1.77)
Missing	21.05	1.30 (0.59 ~ 2.85)	23.81	1.94 (0.71 ~ 5.32)

*p value < 0.05; **p value < 0.01

^aCIAS > 63

^bFigures for the school variable were not listed in this table

OR_u: univariate odds ratios