{'fraction_non_alphanumeric': 0.033865062761506276, 'fraction_numerical': 0.018109309623430964, 'mean_word_length': 5.165659008464329, 'pattern_counts': {'":': 0, '<': 4, '<?xml version=': 0, '>': 4, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 1, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Bullying victimization and life satisfaction among rural left-behind children in Central China: a cross-sectional study

Background: Parental migration has many detrimental health impacts on children. This study described the associations between bullying victimization and life satisfaction among left-behind children(LBC), and examined the interactive effects of left behind experience and bullying victimization on life satisfaction. Methods: Students from first to ninth grade in Central China participated in the present study. Life satisfaction were assessed by Chinese version of revised Bully/Victim Questionnaire and Multidimensional students’ life satisfaction scale(MSLSS). Results: A total of 1013 children were investigated, of which 42.5% were left-behind. We found LBC had a significantly 45% higher risk of being teased in a hurtful way than the non-LBC(OR=1.45, 95%CI: 1.10~1.91), and the LBC had lower self-satisfaction than the non-LBC(b=-0.14, P =0.017). Being teased was only associated with self-satisfaction, and other bullying victimization behaviors had significant impact on all dimensions of life satisfaction( P <0.05). We identified an interactive effect between left behind experience and bullying victimization on school satisfaction( P interaction =0.015), bullying was significantly related with lower school satisfaction in the LBC group(b=-0.69, P <0.001), but no association in the non-LBC group. Also, there was a combined effect between left behind experience and bullying victimization on environment satisfaction( P interaction >0.05), bullying was significantly related with lower environment satisfaction in the LBC group(b=-0.31, P =0.033), while no association was observed in the non-LBC group. Conclusion: There is an interaction of left behind experience and bullying victimization on school satisfaction and a combined effect on environment satisfaction. Left behind experience could significantly amplify the associations between bullying victimization and school satisfaction/environment satisfaction.


Introduction
A recent systematic review on health impact of parent migration of left-behind children (LBC) concluded the health problems contributed to the left behind status may should be emphasized and guarantee more actions and researches to improve their health, in which 91 of 111 studies were conducted in China [1]. Actually, LBC are vulnerable to a lot of health problems, such as depressive symptoms [2], or delayed growth [3]. According to the one-percent national population sample survey in 2015, it was estimated that there are 68.77 million children left behind in hometowns with one or both parents migrating, accounting for 25.4% of the total children population (about 270 million). This indicated that there was one in four children left behind by their migrating parent [4]. With the rapid urbanization of China in the past few decades, left behind phenomenon of children has become more and more common, especially in rural areas and towns. LBC is nowadays defined as children who stay at home with one or both parents relocating elsewhere for working. LBC population would grow up with a special environment with their grandparents or other relatives. Their chances to be well educated, to obtain good physical health or social well-being, to develop healthy lifestyles are all usually vulnerable. What's more, LBC are usually too young to voice for themselves, therefore, the health-related problems of this specific population should be paid more attention.
Previous studies demonstrated that LBC is much more vulnerable to school bullying or peer/sibling victimization since lack of supervision of parents [5]. Yan and colleagues' study in Sichuan and Anhui province showed 43.31% of the LBC reported high bullying victimization score, while only 37.94% in the non-LBC. Chen and colleagues found that parent factors were related with child victimization in rural area of Anhui Province [6].
On the other hand, a lot of studies have investigated the associations between the left behind status or school bullying and the psychological traits. For example, Zhao and colleagues found no association between left behind by migrating parents and life satisfaction, or loneliness [6]. This may due to the left behind phenomenon only influence some different aspects of life satisfaction, such as school satisfaction or friend satisfaction.
With different levels of urbanization in different provinces of China, the impact of left behind phenomenon on school bullying or other aspects of well-being may be various. The phenomenon of LBC highly distributed in major labor export provinces, especially in central and western provinces [7]. Hunan Province as a socio-economically relative deprived province, together with other four provinces (Sichuan, Henan, Anhui, Guangdong Provinces), the LBC population in these areas accounts for 43.64% of the total LBC population in China [7]. But until now, few studies investigated the interact or combined effect of left behind experience and school bullying on multidimensional life satisfaction in Hunan Province. This is a cross-sectional study in children of Hunan Province, China. We hope the study would give us a better understanding of the situation of LBC and provide better care or related education measures for this specific population. The current study aimed to investigate their status of school bullying and multidimensional life satisfaction among the LBC, and also to examine the interact or combined effect of bullying victimization and left behind status on children's life satisfaction.

Location
The present study was conducted in Hunan Province, one of the most populated provinces in Central China, with 68.22 million residents and area of 211800 km 2 in 2016. Hunan Province exports large quantities of labor forces to other coastal developed cities every year. Status of left-behind is quite prevalent in children, especially in rural area or western area of Hunan Province. The estimated number of LBC population is about 4.35 million [7].

Participants
A cross-sectional study was conducted in three different districts in western Hunan Province in July 2018. The study was approved by the Review Board. Informed consents were obtained from all participants and their parents or other legal guardians.

Status of Left behind:
In the present study we used the definition of left behind by Duan [8] and Zhao [9]. One parent or both parents migrating from where the child lived, and left behind their child to live alone or to live with grandparents or other relatives, then the child will be categorized as LBC. For further analysis, we also divided into two groups: LBC with one parent migration group, and LBC with both parents migration group.  [14,15]. MSLSS has five subscales to measure five aspects of life satisfaction, including family, school, friend, environment and self-satisfaction. The subscales are well correlated in expected ways with different criterion measures [14], which is useful for studies of students' life satisfaction.

Statistical analysis
Characteristics of quantitative variables were described by mean ± standard deviation (SD), and categorical variables by number and percentages. Chi-square tests and t-tests were performed to compare the differences for categorical and quantitative variables, respectively. The association between left-behind situations and bullying victimization was examined by univariate and multivariate logistic regression analysis. The associations between bullying victimization or left behind status and MSLSS were examined by univariate and multivariate linear regression analysis. Stratified analyses were conducted by stratified by the left behind status, then we used multivariate linear regression to test the associations between bullying victimization and different domains of life satisfaction, and the interactions were tested by multivariate general linear model with age and sex as covariates. In the stratified analyses of our study, combined effects were defined that there were different effect sizes in the subgroups, but the interaction was not significant (P interaction >0.05), and the interaction was defined that there were different effect sizes in the subgroups, but the interaction was significant(P interaction <0.05) [16].The statistical analyses were all conducted with IBM SPSS 20.0 for windows (SPSS Inc., Chicago, IL, USA).
P<0.05 was considered statistically significant.

Results
General characteristics of the study population A total of 1013 children participated in the present study, with 426 LBC and 582 non-LBC, and the mean age was 8.97 ± 2.43 years. There were 565 boys (55.8%), and 448 girls (44.2%). Among the LBC, 254 children with only one parent migrated for work or other reasons, and 177 children with both parents migrated.
For bullying victimization behaviors, LBC had a significantly higher risk of being teased in a hurtful way than the non-LBC (38.3% vs 30.2%, P = 0.007, Table 1). When stratified by three groups (non-left behind, one parent migration and both parents migration), the prevalence of bullying victimization behaviors was showed in Fig. 1a.
For different dimensions of life satisfaction, non-LBC had a significantly higher selfsatisfaction than non-LBC (4.71 ± 0.86 vs 4.57 ± 0.87, P = 0.012). There is no significant different in family, friend, school and environment satisfaction (P > 0.05, Table 1). When stratified by non left behind, one parent migration and both parents' migration, the average score of different dimensions of life satisfaction among children was illustrated in

Association between left behind experience and bullying victimization
Under the crude model, LBC had a significantly higher risk of being teased in a hurtful way than the non-LBC (OR = 1.43, 95%CI: 1.10-1.86, P = 0.008), and when with further adjustment of age and sex, left behind experience is still a significant risk factor for being teased(OR = 1.45, 95%CI: 1.10 ~ 1.91, P = 0.009). But in the present study, we didn't find significant association between other bullying victimization behaviors with left behind experience(P > 0.05) ( Table 2).
With further stratification by three groups (non left behind, one parent migration and both parents migration), the odds ratio of being teased in a hurtful way is 1.43(95%CI:1.  Table 3. With adjustment of age and sex, we only find a significant association between self-satisfaction and left behind experience

Discussion
Our study found LBC experience a higher risk of bullying victimization, and the left-behind experience and bullying victimizations are also associated with children's life satisfaction Additionally, we firstly found that there is interaction or combined effect between left behind status and bullying victimization on life satisfaction. To the best of our knowledge, this is the first study to explore the interaction or combined effect of bully victimization and left-behind experience on MSLSS. Evidence from our study could help to develop better strategies for psychological intervention among LBC or children suffering bully victimizations.
In the present study, the prevalence of left behind status is 42.5%, this means more than four of ten were left behind. Our results is relative lower than the results of Duan's study, which reported about 51.14% of the rural children were left behind in Hunan province [7].
The possible reason may be that we also included some participants from schools in small towns, while Duan's study only involved the schools of rural areas, where left behind status is more prevalent.
We also found that more than one third of the children were teased by others (33.7%), and left behind status is associated with higher risk of being teased (38.3% vs 30.2%). This is similar to Li et al's study, which also demonstrated that children with parents migration had a higher prevalence of bullying victimizations than the children with parents at home [17]. Additionally, we found that LBC have a significantly lower level of selfsatisfaction than the non-LBC. Which is in accordance with Zhou's study in Jiangxi Province [18], which showed LBC have lower life satisfaction that non-LBC with Diener's Happiness Scale. Left-behind children usually live with their grandparents or other relatives, without proper care from parents, is a special vulnerable population. Therefore, more attention should be paid for LBC, such as self-satisfaction or bully victimization.
The present study also suggested children have experience of being teased had a lower level of self-satisfaction, and other bullying victimization behaviors even had significant associations with all dimensions of life satisfaction (including family, school, friend, environment and self-satisfaction). These findings are similar with Bilić's study among children of Croatia [19], and Serra-Negra's study in adolescents of Brazil [20]. But there are also some differences between our study and others, bullying behavior of Serra-Negra's study focused on verbal school bullying and they used questionnaire of Brazilian National School-Based Adolescent Health Survey (PeNSE). Bilić's study focused on cyber peer bullying. We firstly used Dan Olweus's bullying questionnaire, which included physical, verbal or other bullying victimization behaviors, to assess the associations between bullying victimization and multidimensional life satisfaction. Our results indicated that for children with experience of bullying victimization, we should provide support or help from all aspects, such as family, school, friend, environment and et al. There are some limitations in our study. Firstly, this is a cross-sectional study which could only provide associations but not causal inference. In future, longitudinal studies could be conducted for better understanding of these associations. Secondly, this study is only conducted in 3 districts of Hunan Province by convenience sampling, which may be limited to generalize to other areas of China.

Conclusion
The current study indicated that left behind status and bully victimization has an interaction or combined effect on multidimensional students' life satisfaction. The status of left behind exacerbated the associations between bullying victimization and multidimensional students' life satisfaction. Proper comprehensive interventions measures should be taken to improve the situation of bully victimization and self-satisfaction of LBC.
Also, for the LBC suffering bullying victimization, almost all aspects of life satisfaction should be emphasized and effectively improved.

Ethics approval and consent to participate
The study was approved by the Ethical Committee of Hunan Normal University. Informed consents were obtained from all participants, and also consents were obtained from parents or other legal guardians.

Availability of data and materials
The datasets analyzed in this study are available from the corresponding author (Yi-de Yang, yangyide2007@126.com) upon reasonable request.

Consent for publication
Not applicable as no individual information is presented in the paper.     Figure 2 Association between left behind experience and bullying victimization. Adjusted model was adjusted for age and sex.