Background
Bullying is an aggressive act or social interaction in which an individual or group with a power advantage repeatedly humiliates or intimidates someone [
1]. There are several types of bullying, traditional bullying (physical, verbal, and relational), and a new form of cyber bullying exerted via electronic media [
2]. School bullying among children and adolescents is prevalent globally, with estimated prevalence surpassed 65% in some countries [
3]. Both traditional and cyber bullying can impose detrimental influence on mental health of children and adolescents [
4‐
6]. For instance, bullying can lead to increased risk of depression, anxiety, post-traumatic stress disorder (PTSD), interpersonal violence, and suicidal behaviors [
7‐
10].
Children and adolescents can be implicated into school bullying as pure victims, pure bullies, or bully-victims [
11]. It has been found that any role of school bullying involvement is associated with significantly impaired short-term and long-term mental health status, particularly for bullying victims [
12]. Studies have disclosed that bullying victims were observed poorer academic performance, and increased risk of physical, emotional, and behavioral problems [
13‐
14]. In addition, the risk of self-harm for bullying victims was about 6 times compared with people who were not involved in school bullying [
15].
Searching for influencing factors of school bullying victimization is essential for developing effective prevention policies and measures. Many published studies have identified risk factors at individual level, such as body weight, physical disability, anxiety, depression, low self-esteem, etc. [
16].. It has been found that social factors may also have a significant effect on bullying victimization. For instance, Liang et al. reported that adolescents in countries with food insecurity were more likely to be victims of bullying, with an odds ratio (OR) of 1.37 [
17]. In addition, Deryol et al. observed that countries with high inequality-adjusted Human Development Index (HDI) had a lower prevalence of bullying victimization [
18].
Social poverty, measured by indicators such as monthly household per capita income (PCI) and Poverty Gap (PG), reflect either socioeconomic status (absolute poverty) or inequality (relative poverty) of the society. It has been found that social poverty is significantly related to higher risk of cognitive development problems, social-emotional issues, anxiety, depression, and other mental health problems in children and adolescents [
19‐
21]. Given the intimate relationship between mental health and school bullying behaviors in youths, it is reasonable to suspect a connection between social poverty and school bullying victimization. However, this hypothesis has not been effectively discussed.
In the current study, we intend to evaluate the association between social poverty indicators and prevalence of school bullying victimization at country level. The findings of our study are expected to help formulate effective regional or national school bullying victimization prevention and control initiatives.
Discussion
In this study by using the GSHS database, as expected, we found a significant association between social poverty and school bullying victimization in children and adolescents at country level, with a higher level of social poverty related to increased prevalence of bullying victimization. However, among all the 6 social poverty indicators that we investigated, only PHR, PCI and WPI showed this significant association with bullying victimization. As for different types of bullying victimization, their associations with social poverty indicators differed, and the strongest association was seen for verbal bullying. The main findings of our study can provide valuable information for devising bullying victimization prevention and control strategies and measures in consideration of national poverty levels.
The positive association between social poverty status and school bullying victimization that we found can be well justified by existing literature. A previously published US study revealed that, youth with poverty-related problems of both food and housing insecurity were more than 3 times likely to report victimization, compared with youth without these adversities [
28]. Moreover, based on the family investment model, impoverished families only have limited funds to invest in necessities of life for children, therefore children are more likely to be deprived [
29‐
31]. Deprived children are seen higher risk of low self-esteem and being excluded by peers, which increased their chance of being bullied [
32‐
34]. Besides, poverty leads to poor living conditions for adolescents, together with frequent move, family conflicts caused by economic pressures or inadequate awareness of family support, all of which can contribute to increased risk of bullying victimization [
35‐
36].
An interesting finding of our study is that, for the 6 social poverty indicators that we analyzed, only the three indicators of absolute poverty (PHR, PCI, WPI) were significantly associated with bullying victimization, whereas the other three indicators measuring socioeconomic inequality (PG, SPG, GINI) showed insignificant impact. This finding is somewhat different from previous study by Fajnzylber et al., which found a clear association between inequality and violence, rather than poverty and violence [
37]. More specifically with respect to bullying, some studies have found a relation between bullying and inequality, but not bullying and poverty, at country and school level [
38‐
39], in contrast to the insignificant association between inequality and school bullying victimization that we found. One possible explanation to this heterogeneity could be that those studies primarily used subjective measures of inequality, compared with the objective inequality indicators that we used in the current study. Considering subjective inequality indicators are more informative than objective indices [
40], it is possible that the association between inequality and bullying victimization was underestimated in the current study. Our findings suggest that, for countries characterized in absolute poverty, when constructing and implementing bullying intervention measures, children and adolescents who are living under the poverty line should be prioritized.
Another important finding to be noticed is that, for different types of bullying victimization, their associations with social poverty indicators varied. Verbal bullying victimization showed the strongest association with social poverty, followed by physical and relational bullying victimization. Verbal bullying is the most common type of traditional bullying [
41]. According to literature, in children and adolescents, the prevalence of verbal bullying involvement can be as high as 53%, compared with 51% for relational bullying, and 21% for physical bullying [
42]. Our study results suggest that this most common type of school bullying can be more significantly influenced by social poverty. Studies about natural or planned experiments in reducing poverty should be conducted to determine the effect on school bullying, especially on verbal bullying.
The current study is among the first attempts in estimating the association between social poverty and school bullying victimization at country level. Multinational representative survey data further consolidates the validity of our findings. Nevertheless, several limitations should be recognized. First, both the social poverty indicators and school bullying prevalence rates were measured at country level, therefore the essence of our study is ecological, which is prone to ecological bias. Future studies by using individual level data are warranted. Second, the GSHS is implemented in limited countries, and in this study, we only included countries with complete survey data in school bullying, therefore our results may suffer from selection bias. Third, because of data unavailability, other social indicators which may confound the association between social poverty and school bullying victimization could not be included and controlled for, therefore residual confounding may exist. Fourth, the sample size is small, and a larger sample size may yield more significant results. Fifth, the study sample do not include very rich or very poor countries, so it is possible that variance in poverty could be much larger with a larger sample size. Finally, comparing the level of school bullying depends on similar understanding of what the measures ask, however, it is difficult to translate the word “bullying” to different languages.
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