Table 2.

Results of subgroup analysis of the association between bullying and depression in children and adolescents

Group	Number of included studies	Heterogeneity		Meta-analysis results
		I2(%)	P	OR(95% CI)	P
Sex
Males and females	30	97.6	< 0.001	2.78(2.30,3.38)	< 0.001
Females	1	0.0	1.000	2.10(0.90,4.90)	0.086
Year
After 2015	15	91.5	< 0.001	2.48(2.06,3.00)	< 0.001
Before 2015	16	98.0	< 0.001	3.06(2.24,4.18)	< 0.001
Continent
Asia	14	90.7	< 0.001	2.50(2.03,3.09)	< 0.001
Europe	13	98.4	< 0.001	3.11(2.22,4.36)	< 0.001
North America	2	0.0	0.813	2.77(2.43,3.17)	< 0.001
Oceania	2	0.0	0.712	2.29(1.57, 3.35)	< 0.001
Sampling method
Simple random	7	96.2	0.001	2.47(1.63,3.76)	< 0.001
Cluster random	17	93.4	< 0.001	2.67(2.23,3.21)	< 0.001
General survey	4	82.1	< 0.001	3.80(2.50,5.77)	< 0.001
Types of bullying
Traditional	16	98.0	< 0.001	2.38(1.89,3.00)	< 0.001
Cyber	11	79.5	< 0.001	2.93(2.26, 3.78)	< 0.001
Traditional and cyber	4	79.0	0.003	4.49(3.30,6.12)	< 0.001
Article quality
Medium quality	21	96.8	< 0.001	2.72( 2.17,3.42)	< 0.001
High quality	10	91.3	< 0.001	2.85(2.32,3.50)	< 0.001