Consequences of bullying victimization in childhood and adolescence: A systematic review and meta-analysis

Table 1 Associations between bullying victimization in children and adolescents and mental health outcomes

	Data points	Pooled OR	95%CI lower bound	95%CI upper bound	Cochran’s Q	I² (%)	Test for heterogeneity (P value)
Poor mental health
Pooling all	39	1.6	1.42	1.81	303.79	87.49	< 0.01
Study type
Retrospective/cross-sectional	25	1.8	1.44	2.25	211.78	88.67	< 0.01
Prospective cohort	14	1.39	1.29	1.49	22.12	41.24	0.05
Sex
Male	3	2.49	1.86	3.32	0.44	0	0.8
Female	3	2.38	1.41	4	6.95	71.22	0.03
Twins	3	1.41	1.27	1.56	2.5	20.09	0.29
Severity of bullying
Sometimes	8	1.5	1.27	1.76	47.68	85.23	< 0.01
Frequent	8	1.52	1.18	1.95	51.4	86.38	< 0.01
Anxiety
Pooling all	58	1.77	1.34	2.33	3816.23	98.51	< 0.01
Anxiety	32	1.56	1.39	1.75	434.61	92.87	< 0.01
Social phobia	8	2.48	1.59	3.86	11.01	36.41	0.14
Generalised anxiety disorder	2	2.83	1.38	5.84	0.11	0	0.74
PTSD	12	6.41	1.93	21.22	497.11	97.79	< 0.01
Specific phobia	1	2.4	1	5.6	-	-	-
Separation anxiety disorder	1	4.6	2	10.6	-	-	-
Panic disorder	1	3.1	1.5	6.5	-	-	-
Agoraphobia	1	4.6	1.7	12.5	-	-	-
Study type
Retrospective/cross-sectional	39	2.02	1.21	3.38	3697.48	98.97	< 0.01
Prospective cohort	19	1.29	1.06	1.55	84.03	78.58	< 0.01
Age of bullying
Less than 13 yr	13	1.4	0.58	3.41	123.12	90.25	< 0.01
Older than 13 yr	45	1.81	1.29	2.56	3688.82	98.81	< 0.01
Sex
Male	16	1.84	1.3	2.59	112.23	86.63	< 0.01
Female	15	2.46	1.74	3.48	124.39	88.74	< 0.01
Severity of bullying
Sometimes	7	1.46	1.06	2	43.41	86.18	< 0.01
Frequent	25	2.47	1.94	3.14	122.47	80.4	< 0.01
Geographic location and income level
Low-to-middle income	22	2.41	1.75	3.32	175.97	88.07	< 0.01
High income	36	1.67	1.24	2.25	3441.17	98.98	< 0.01
Depression
Pooling all	92	2.21	1.34	3.65	14525.32	99.37	< 0.01
Major depressive disorder	2	2.27	0.68	7.57	2.07	51.63	0.15
Study type
Retrospective/cross-sectional	63	1.95	1.24	3.07	2594.97	97.61	< 0.01
Prospective cohort	29	3.03	1.31	6.98	4583.05	99.39	< 0.01
Age of bullying
Less than 13 yr	36	2.11	1.63	2.72	544.9	93.58	< 0.01
Older than 13 yr	56	2.29	1.24	4.23	13806.72	99.6	< 0.01
Sex
Male	27	2.07	1.48	2.89	443.84	94.14	< 0.01
Female	21	2.13	1.18	3.86	313.5	93.62	< 0.01
Severity of bullying
Sometimes	15	1.78	1.39	2.28	78.61	82.19	< 0.01
Frequent	28	3.26	2.45	4.34	224.43	87.97	< 0.01
Geographic location and income level
Low-to-middle income	13	2.53	1.75	3.68	143.98	91.67	< 0.01
High income	79	2.15	1.26	3.68	14351.72	99.46	< 0.01
Psychotic symptoms
Specific psychiatric symptoms	6	2.07	1.49	2.87	20.57	75.69	< 0.01
Non-clinical psychotic experiences	9	2.68	2.03	3.54	15.1	47.03	0.06
Psychotic symptoms	5	2.73	1.97	3.77	10.86	63.16	0.03
Personality disorders
Anti-social personality disorder	2	0.58	0.15	2.28	2.53	60.48	0.11
Borderline personality disorder	3	2.2	1.4	3.46	4.8	58.31	0.09
Eating disorders
Bulimia nervosa	1	3	1.4	6.2	-	-	-
Anorexia nervosa	1	0.004	0	251	-	-	-
Non-suicidal self injury
Pooling all	30	1.75	1.4	2.19	749.02	96.13	< 0.01
Study type
Retrospective/cross-sectional	21	1.55	1.09	2.22	721.15	97.23	< 0.01
Prospective cohort	9	1.65	1.34	2.02	19.39	58.75	0.01
Sex
Male	6	4.86	3.35	7.07	13.56	63.12	0.02
Female	4	2.7	2	3.65	8.92	66.37	0.03
Twins	2	2.57	1.79	3.7	0.12	0	0.73
Severity of bullying
Sometimes	6	1.57	1.09	2.25	34.04	85.31	< 0.01
Frequent	7	2.52	1.6	3.97	54.49	88.99	< 0.01
Suicidal ideation
Pooling all	105	1.77	1.56	2.02	2093.5	95.03	< 0.01
Study type
Retrospective/cross-sectional	86	1.8	1.56	2.09	2037.46	95.83	< 0.01
Prospective cohort	19	1.68	1.38	2.05	38.98	53.82	< 0.01
Age of bullying
Less than 13 yr	22	1.85	1.48	2.3	74.4	71.77	< 0.01
Older than 13 yr	83	1.75	1.51	2.03	1984.06	95.87	< 0.01
Sex
Male	21	1.95	1.64	2.32	76.6	73.89	< 0.01
Female	18	2.15	1.84	2.52	33.15	48.72	0.01
Severity of bullying
Sometimes	16	1.53	1.28	1.82	35.19	57.38	< 0.01
Frequent	21	2.59	2.06	3.25	49.83	59.87	< 0.01
Geographic location and income level
Low-to-middle income	11	1.31	1.06	1.61	60.02	83.34	< 0.01
High income	94	1.8	1.43	2.26	1894.91	95.09	< 0.01
Suicide attempt
Pooling all	48	2.13	1.66	2.73	1110.46	95.77	< 0.01
Suicidal attempt/non-suicidal self injury	3	2.97	1.68	5.23	6.33	68.42	0.04
Study type
Retrospective/cross-sectional	40	2.03	1.46	2.84	1105.65	96.47	< 0.01
Prospective cohort	8	2.04	1.38	3.01	4.34	0	0.74
Age of bullying
Less than 13 yr	11	2.11	1.65	2.69	11.49	12.98	0.32
Older than 13 yr	37	1.52	0.82	2.83	579.75	93.79	< 0.01
Sex
Male	7	2.93	1.65	5.18	15.38	54.5	0.02
Female	7	2.89	1.52	5.49	24.23	71.11	< 0.01
Severity of bullying
Sometimes	9	2.19	1.71	2.8	7.52	0	0.48
Frequent	12	3.77	2.55	5.58	28.31	61.14	< 0.01
Geographic location and income level
Low-to-middle income	4	1.91	1.07	3.43	22.18	86.47	< 0.01
High income	44	2.17	1.69	2.8	1084.61	96.04	< 0.01
Behavioural problems
Pooling all	54	1.37	1.18	1.59	862.4	93.85	< 0.01
Study type
Retrospective/cross-sectional	29	1.18	0.99	1.41	311.21	91	< 0.01
Prospective cohort	25	1.56	0.94	2.58	413.53	94.2	< 0.01
Sex
Male	9	1.35	0.68	2.67	450.06	98.22	< 0.01
Female	7	1.99	0.97	4.1	88.07	93.19	< 0.01
Twins	2	1.19	0.94	1.5	7.31	86.31	0.01
Severity of bullying
Sometimes	8	1.95	0.92	4.1	243.71	97.13	< 0.01
Frequent	8	2.26	0.76	6.69	163.51	95.72	< 0.01
Externalising behaviours	20	1.29	1.12	1.5	157.09	87.9	< 0.01
Delinquent/deviant behaviour	24	1.99	1.24	3.2	423.78	94.57	< 0.01
Missed school	7	1.49	0.99	2.23	38.4	84.37	< 0.01
Disruptive behavioural disorders
Attention deficit hyperactivity disorder	1	2.6	0.8	8.5	-	-	-
Oppositional defiant disorder	1	0.8	0.3	2.5	-	-	-
Conduct disorder	1	2.6	0.8	8.8	-	-	-
Other mental health outcomes (not included above)
Nervousness	9	1.82	1.51	2.2	135.59	94.1	< 0.01
Powerlessness	2	1.06	0.95	1.18	1.64	39.18	0.2
Feeling low	7	2.26	1.66	3.08	299.47	98	< 0.01
Irritability or bad temper	7	1.82	1.51	2.2	125.07	95.2	< 0.01
Feel helpless	5	3.2	2.01	5.09	273.51	98.54	< 0.01
Feeling tense	3	3.07	2.06	4.56	3.02	33.75	0.22
Unhappy/sad	12	1.25	0.55	2.84	668.61	98.35	< 0.01
Worried	4	1.27	1.09	1.47	314.35	99.05	< 0.01
Afraid	3	2.68	1.18	6.09	9.49	78.92	0.01

Table 2 Associations between bullying victimization in children and adolescents and substance use

	Data points	Pooled OR	95%CI lower bound	95%CI upper bound	Cochran’s Q	I² (%)	Test for heterogeneity (P value)
Alcohol use
Pooling all	53	1.26	1.00	1.58	10328.18	99.5	< 0.01
Study type
Retrospective/cross-sectional	38	1.28	0.88	1.84	10256.15	99.64	< 0.01
Prospective cohort	15	1.19	0.87	1.62	67.87	79.37	< 0.01
Sex
Male	6	0.61	0.49	0.77	4.89	0.00	0.43
Female	4	0.88	0.50	1.57	6.36	52.86	0.1
Severity of bullying
Sometimes	6	1.72	0.84	3.50	86.17	94.20	< 0.01
Frequent	13	1.53	0.78	3.03	332.27	96.39	< 0.01
Frequency of alcohol consumption
Sometimes	24	1.52	1.08	2.13	8416.94	99.73	< 0.01
Frequent	29	0.99	0.86	1.14	251.81	88.88	< 0.01
Age of bullying
Less than 13 yr	16	1.23	0.93	1.63	1618.14	99.07	< 0.01
Older than 13 yr	37	1.31	0.96	1.80	6896.71	99.48	< 0.01
Geographic location and income level
Low-to-middle income	11	1.37	0.75	2.49	8328.21	99.88	< 0.01
High income	42	1.08	0.91	1.27	462.84	91.14	< 0.01
Tobacco use
Pooling all	35	1.36	0.96	1.92	418.71	91.88	< 0.01
Study type
Retrospective/cross-sectional	26	1.17	0.59	2.31	394.92	93.67	< 0.01
Prospective cohort	9	1.62	1.31	1.99	11.48	30.33	0.18
Sex
Male	3	0.97	0.59	1.58	8.23	75.7	0.02
Female	3	0.51	0.37	0.68	1.78	0	0.41
Severity of bullying
Sometimes	4	1.89	0.83	4.33	71.38	95.8	< 0.01
Frequent	4	3.19	1.19	8.58	39.85	92.47	< 0.01
Frequency of smoking
Sometimes	28	1.36	0.89	2.06	400.72	93.26	< 0.01
Frequent	7	1.35	1.00	1.84	16.28	63.16	0.01
Illicit drug use
Pooling all	34	1.41	1.10	1.81	677.62	95.13	< 0.01
Study type
Retrospective/cross-sectional	11	2.43	1.42	4.15	297.3	96.64	< 0.01
Prospective cohort	23	1.27	1.12	1.44	67.23	67.28	< 0.01
Sex
Male	7	1.04	0.81	1.33	32.84	81.73	< 0.01
Female	5	1.17	1.03	1.33	3.26	0.00	0.52
Severity of bullying
Sometimes	7	1.22	0.78	1.90	160.47	96.26	< 0.01
Frequent	8	1.14	0.43	3.00	465.43	98.50	< 0.01
Geographic location and income level
Low-to-middle income	5	4.05	2.18	7.55	98.61	95.94	< 0.01
High income	29	1.31	1.15	1.48	103.73	73.01	< 0.01
Cannabis only all	9	1.42	0.96	2.12	23.32	65.70	< 0.01
Study type
Retrospective/cross-sectional	1	2.46	1.53	3.95	-	-	-
Prospective cohort	8	1.36	0.90	2.05	18.14	61.41	0.01

Table 3 Associations between bullying victimization in children and adolescents and other health outcomes

	Data points	Pooled OR	95%CI lower bound	95%CI upper bound	Cochran’s Q	I² (%)	Test for heterogeneity (P value)
Somatic symptoms
Unspecified psychosomatic symptoms	25	2.00	1.54	2.60	232.02	89.66	< 0.01
Stomach ache	25	1.76	1.53	2.03	138.73	82.7	< 0.01
Sleeping difficulties	24	1.73	1.46	2.05	574.91	96	< 0.01
Headache	26	1.64	1.38	1.94	169.16	85.22	< 0.01
Bedwetting	3	2.51	1.44	4.37	4.93	59.45	0.08
Feeling tired	2	2.68	1.39	5.19	1.22	17.87	0.27
Poor appetite	2	2.23	1.60	3.12	0	0	0.95
Back pain	8	1.67	1.43	1.95	73.53	90.48	< 0.01
Skin problems	1	1.82	1.33	251	-	-	-
Dizziness	9	1.64	1.38	1.95	76.57	89.55	< 0.01
Eating and weight related problems
Binge eating	2	2.66	1.68	4.22	0.57	0	0.45
Non-diet soft drink consumption	1	1.21	1.04	1.41	-	-	-
Skips breakfast	6	1.41	1.20	1.65	11.89	57.94	0.04
Underweight
Pooling all	2	1.27	0.73	2.21	0	0	0.96
Sex
Male	1	1.28	0.69	2.37	-	-	-
Female	1	1.24	0.19	2.29	-	-	-
Overweight
Pooling all	14	1.68	1.21	2.33	82.69	84.28	< 0.01
Study type
Retrospective/cross- sectional	12	1.99	1.39	2.85	65.45	83.19	< 0.01
Prospective cohort	2	0.98	0.64	1.49	1.92	47.97	0.17
Sex
Male	7	1.22	0.99	1.49	8.04	25.4	0.23
Female	7	2.22	1.28	3.84	50.17	88.04	< 0.01
Severity of bullying
Sometimes	2	1.32	1.00	1.74	0.09	0	0.77
Frequent	6	1.14	0.88	1.47	7.37	32.2	0.19
Obese
Pooling all	13	1.78	1.42	2.21	14.68	18.28	0.26
Study type
Retrospective/cross-sectional	10	1.97	1.53	2.53	7.22	0	0.61
Prospective cohort	3	1.57	0.89	2.77	6.89	70.97	0.03
Sex
Male	6	1.94	1.45	2.60	4.88	0	0.43
Female	6	2.15	1.57	2.94	2.22	0	0.82
Severity of bullying
Sometimes	2	1.63	1.11	2.38	0.52	0	0.47
Frequent	6	2.09	1.59	2.75	5.26	4.86	0.39
Sexual behaviour problems
Teen parent	5	1.26	0.81	1.97	15.11	73.53	< 0.01
Risky sexual behaviour	4	2.28	0.95	5.48	23.43	87.2	< 0.01
Early onset of sexual activities	3	1.44	0.90	2.30	7.38	72.91	0.02
Pooling all	12	1.51	1.01	2.25	85.66	87.16	< 0.01
Study type
Retrospective/cross-sectional	3	1.77	0.42	7.52	54.97	96.36	< 0.01
Prospective cohort	9	1.34	0.98	1.84	23.88	66.51	< 0.01
Severity of bullying
Sometimes	2	0.81	0.51	1.28	2.46	59.32	0.12
Frequent	4	2.38	1.05	5.41	27.55	89.11	< 0.01
Health services utilised
Pooling all	16	1.20	0.99	1.45	34.37	56.36	< 0.01
Study type
Retrospective/cross-sectional	14	1.14	0.94	1.39	27.91	53.42	0.01
Prospective cohort	2	1.54	0.65	3.61	4.43	77.43	0.04
Sex
Male	7	1.17	0.95	1.43	3.54	0	0.74
Female	7	1.41	1.12	1.77	11.16	46.25	0.08
General medication use
Pooling all	12	1.16	0.80	1.70	117.98	90.68	< 0.01
Study type
Retrospective/cross-sectional	11	0.99	0.56	1.75	112.26	91.09	< 0.01
Prospective cohort	1	1.67	1.09	2.58	-	-	-
Sex
Male
Medication for headache	2	1.43	1.06	1.93	2.34	57.21	0.13
Medication for stomach-ache	2	1.09	0.72	1.65	1.9	47.5	0.17
Female
Medication for headache	2	1.19	0.98	1.45	1.33	24.79	0.25
Medication for stomach-ache	2	1.23	1.01	1.5	0.27	0	0.61
Severity of bullying
Sometimes	5	1.26	0.99	1.59	15.46	74.13	< 0.01
Frequent	5	1.72	1.11	2.67	24.9	83.93	< 0.01
Over the counter drug misuse	3	0.95	0.19	4.66	76.34	97.38	< 0.01
Psychotropic medication use
Pooling all	13	1.28	0.72	2.26	205.76	94.17	< 0.01
Study type
Retrospective/cross-sectional	11	0.95	0.32	2.8	195.34	94.88	< 0.01
Prospective cohort	2	1.31	0.66	2.6	5.61	82.18	0.02
Sex
Male
Medication for nervousness	2	1.32	0.42	4.1	14.98	93.32	< 0.01
Medication for sleeping	2	1.89	1.33	2.67	1.59	37.28	0.21
Female
Medication for nervousness	2	1.97	1.49	2.59	1.06	5.88	0.3
Medication for sleeping	2	1.83	1.42	2.36	0.27	0	0.6
Severity of bullying
Sometimes	6	1.66	1.26	2.18	18.54	73.04	< 0.01
Frequent	6	1.88	1.17	3.03	31.93	84.34	< 0.01
Prescription drug misuse	3	0.92	0.17	5.07	88.16	97.73	< 0.01
Poor general health
Pooling all	29	1.83	1.45	2.31	133.31	79	< 0.01
Study type
Retrospective/cross-sectional	22	1.71	1.21	2.42	112.06	81.26	< 0.01
Prospective cohort	7	1.56	1.07	2.28	19.72	69.57	< 0.01
Sex
Male	9	1.95	1.16	3.27	20.5	60.98	0.01
Female	9	2.36	1.11	5.04	52.78	84.84	< 0.01
Severity of bullying
Sometimes	4	2.16	1.10	4.26	9.15	67.21	0.03
Frequent	4	6.96	2.17	22.35	16.72	82.05	< 0.01

Table 4 Associations between bullying victimization and academic and social functioning

	Data points	Pooled OR	95%CI lower bound	95%CI upper bound	Cochran’s Q	I² (%)	Test for heterogeneity (P value)
Poor school functioning
Pooling all	6	1.10	0.87	1.38	82	93.9	< 0.01
Study type
Retrospective/cross-sectional	3	1.24	1.22	1.27	0.33	0	0.85
Prospective cohort	3	0.90	0.76	1.08	8.15	75.46	0.02
Severity of bullying
Sometimes	1	0.96	0.88	1.04	-	-	-
Frequent	1	0.98	0.76	1.19	-	-	-
Academic achievement
Poor academic achievement
Pooling all	6	1.33	1.06	1.66	11.17	55.25	0.02
Study type
Retrospective/cross-sectional	6	1.33	1.06	1.66	11.17	55.25	0.02
Good academic achievement
Pooling all	4	0.71	0.60	0.85	8.81	65.97	0.07
Study type
Retrospective/cross-sectional	3	0.86	0.8	0.92	2.89	30.69	0.58
Prospective cohort	1	0.46	0.28	0.76	-	-	-
Sex
Male	2	1.24	0.88	1.74	2.49	59.8	0.65
Female	2	1.32	0.99	1.75	1.4	28.7	0.84
Severity of bullying
Sometimes	1	0.88	0.83	0.93	-	-	-
Frequent	1	0.80	0.70	0.93	-	-	-
Poor financial and occupational functioning
Pooling all prospective cohort	16	1.14	0.87	1.50	92.97	83.86	< 0.01
Severity of bullying
Sometimes	3	1.00	0.9	1.11	0.04	0	0.98
Frequent	3	0.81	0.61	1.07	2.68	25.32	0.26
Social isolation
Loneliness
Pooling all	13	1.89	1.39	2.57	3120.66	99.62	< 0.01
Study type
Retrospective/cross-sectional	13	1.89	1.39	2.57	3120.66	99.62	< 0.01
Sex
Male	4	2.58	1.62	4.10	222.21	98.65	< 0.01
Female	3	3.92	1.95	7.90	19.53	89.76	< 0.01
Severity of bullying
Sometimes	2	2.09	1.98	2.20	0.39	0	0.53
Frequent	4	4.12	2.24	7.60	23.32	87.13	< 0.01
Self esteem
Pooling all	14	0.99	0.92	1.07	93.73	86.13	< 0.01
Study type
Retrospective/cross-sectional	4	1.13	0.83	1.54	76.58	96.08	< 0.01
Prospective cohort	10	0.97	0.93	1.01	12.32	26.93	0.2
Sex
Male	5	0.96	0.88	1.06	20.65	80.63	< 0.01
Female	4	0.95	0.88	1.03	5.74	47.7	0.13
Severity of bullying
Sometimes	5	0.99	0.95	1.04	1.61	0	0.81
Frequent	5	0.95	0.87	1.04	9.65	58.54	0.05
Social problems
Pooling all	22	1.02	0.74	1.42	427.13	95.08	< 0.01
Study type
Retrospective/cross-sectional	5	2.86	1.42	5.76	38.09	89.5	< 0.01
Prospective cohort	17	0.89	0.74	1.06	72.36	77.89	< 0.01
Sex
Male	1	2.89	1.45	5.73	-	-	-
Female	1	8.10	4.60	14.26	-	-	-
Severity of bullying
Sometimes	3	0.9	0.83	0.96	0.5	0	0.78
Frequent	3	0.81	0.72	0.92	3.67	45.49	0.16
Criminal behaviour
Pooling all	33	1.04	0.78	1.39	133.36	76.01	< 0.01
Carrying a weapon	8	1.59	1.27	1.98	19.16	63.47	0.01
Violent offense/behaviour	6	1.25	1.01	1.56	2.46	0	0.78
Study type
Retrospective/cross-sectional	9	1.01	0.47	2.14	106.83	92.51	< 0.01
Prospective cohort	24	1.05	0.92	1.19	25.72	10.58	0.31
Sex
Male	11	1.00	0.82	1.22	13.78	27.43	0.18
Female	4	0.70	0.46	1.04	0.38	0	0.94
Severity of bullying
Sometimes	5	0.97	0.75	1.26	7.37	45.74	0.12
Frequent	8	1.22	0.86	1.74	16.33	57.13	0.02
Other outcomes reported
Good quality of later life	6	0.85	0.78	0.93	17.42	71.29	< 0.01
Poor life satisfaction	6	2.26	1.41	3.60	3.79	0	0.58
Problematic internet usage	1	2.36	1.58	3.54	-	-	-
Picked on by siblings	1	1.69	1.38	2.07	-	-	-

Table 5 Strength of evidence for a causal relationship between bullying victimization and adverse health or psychosocial problems

Strength of evidence	Adverse health or psychosocial problem
Convincing	Anxiety; depression; poor mental health; poor general health; non-suicidal self-injury; suicide attempts; suicide ideation
Probable	Tobacco use; illicit drug use
Possible	Alcohol use; psychotic symptoms; increased use of health services in females; lower academic achievement; social isolation; loneliness; psychosomatic symptoms, overweight and obesity
Insufficient	Binge eating; bulimia nervosa; borderline personality disorder; behavioural problems; carrying a weapon; general medication use; health services sought; poor financial and occupational functioning; psychotropic medication use; poor school functioning; sexual behavioural problems; poor life satisfaction