Risk and protective factors related to domestic violence against Brazilian adolescents

REV BRAS EPIDEMIOL 2020; 23: E200003.SUPL.1 ABSTRACT: Objective: To describe the factors associated with domestic violence against Brazilian adolescents. Methodology: Descriptive analysis of the variables and calculation of the prevalence of intrafamily violence reported by the students was performed, followed by multinomial regression with calculation of the adjusted odds ratio to analyze the association between the variables and the outcome investigated. Results: Black skin color (ORa = 1.9; 95%CI 1.4 – 2.7) and brown (ORa = 1.4; 95%CI 1.0 – 1.9), insomnia (ORa = 1.8; 95%CI 1.4 – 2.4), bullying (ORa = 2.5; 95%CI 1.7 – 3.7) and alcohol consumption (ORa = 1.5; 95%CI 1.1 – 1.9) increased the chances of adolescents suffering an episode of intrafamily violence. Bullying (ORa = 3.9; 95%CI 2.8 – 5.3) and alcohol consumption (ORa = 2.2; 95%CI 1.7 – 2.7) contributed up to 4 times more not to suffer more than one episode of domestic violence. Habits such as eating with family (ORa = 0.7; 95%CI 0.5 – 1.0) and having parents who understand their problems (ORa = 0.6; 95%CI 0.5 – 0,7) proved to be protective factors for intrafamily violence. Conclusion: Intrafamily violence against adolescents is related to family interactions, psychoactive substance use and violence in the school environment. Thus, it reveals the importance of the participation of parents and guardians in the prevention of violence and risk behaviors in the lives of Brazilian adolescents.


INTRODUCTION
The World Health Organization (WHO) and the Brazilian Ministry of Health consider violence a serious public health issue, and children and adolescents are the main victims of all types of violence, especially domestic 1,2 . The family -understood as a unit of protection and support -is becoming a source of violence and aggression, with one in every ten Brazilian adolescents claiming to have experienced physical abuse by a relative in 2012 3,4 . Domestic violence against adolescents can be regarded as acts that jeopardize the well-being and the physical, mental, and social development of the adolescent, inflicted by a family member under different forms of aggression, such as neglect and physical, sexual, and psychological abuse 5 .
National and international studies underline the concern with the high prevalence of violence against children and adolescents in the world, indicating the need for interventions in this area 6 . In 2009, Brazil held the first National Adolescent School-based Health Survey (Pesquisa Nacional de Saúde do Escolar -PeNSE), with new editions in 2012 and 2015. PeNSE is a survey conducted with 6 th to 9 th -grade elementary school students (former 5 th and 8 th grades) and 1 st to 3 rd -grade high school students that monitors several topics on adolescent health, including domestic violence or abuse, which has grown over the successive editions of PeNSE -9.5% in 2019, 10.6% in 2012, reaching a prevalence of 14.5% in 2015 4 .

METHODS
This cross-sectional study analyzed secondary data from Sample 2 of PeNSE 2015 10,11 . PeNSE 2015 used two samples of adolescents with different sampling plans. The first sample (Sample 1) consisted of students attending the 9 th grade of elementary school (former 8 th grade) in public and private schools located in urban and rural areas over the national territory in 2015 9 . Sample 2 comprised students aged 13 to 17 years who attended the 6 th to 9 th grade of elementary school (former 5 th to 8 th grades) and the 1 st to 3 rd grade of high school in public and private schools over the Brazilian territory 9 .
This study analyzed the Sample 2 of PeNSE 2015, which, contrary to Sample 1, allows comparing the distribution by age in each geographic stratum of students aged 13 to 17 years. Sample 2 of PeNSE also allows the identification and monitoring of factors related to the physical-biological development of students and the time of exposure to conditions that pose a risk to their health, in addition to providing a greater possibility of comparison with international indicators 9 .
PeNSE used stratified cluster sampling designs for each of the five main Brazilian regions (Northeast, Southeast, South, North, and Midwest), resulting in five strata 9 . We adopted the weight calibration for age and main region to match the estimated total of individuals enrolled and of schools registered in the microdata system of the 2015 School Census 9 .
Thus, Sample 2 of PeNSE (n=10,926) comprised students aged 13 to 17 years who attended the 6 th to 9 th grade of elementary school and the 1 st to 3 rd grade of high school in public in private schools over the Brazilian territory in 2015 9 . The main regions constituted the primary sampling unit (PSU), the secondary sampling units (SSU), and the tertiary sampling units (TSU) 10 .
On smartphones, the students answered the structured self-administered questionnaire based on instruments used in global surveys 10 . The outcome of experiencing domestic violence was investigated by the question "In the past 30 days, how many times have you been physically abused by an adult from your family?", categorized into: • none; • once in the past 30 days; • more than once (two or more times in the past 30 days).
The variables that characterized the adolescent victims of domestic violence were divided into four groups according to concept similarity, as follows: a) Sociodemographic characteristics: • Gender: male and female; • Ethnicity: white, black, Asian, multiracial, and indigenous; • Maternal schooling: the level of education (degree) of the student's mother at the time of data collection, classified into four categories -no education/ incomplete elementary school, complete elementary school/incomplete high school, complete high school/incomplete higher education, and complete higher education; • School: related to its administrative affiliation -public and private; b) Mental health: • Friends: number of close friends reported by the student, categorized as no (no friend) or yes (one or more friends); • Insomnia: the frequency that the student could not sleep at night because they were apprehensive about something, classified as no (never, rarely, and sometimes in the past 12 months) or yes (most of the time, always in the past 12 months); • Victim of bullying: the frequency that a classmate ridiculed, mocked, taunted, intimidated, or made fun of the adolescent to the point that they were hurt, upset, angry, insulted, or humiliated, divided into three categories -never, rarely/ sometimes, and most of the time/always. c) Behavior and lifestyle: • Smoking: frequency in days that the student smoked cigarettes in the prior 30 days, categorized into no (no days) and yes (1 to all 30 days); • Alcohol consumption: frequency in days that the adolescent drank at least a drink or dose of alcoholic beverage in the previous 30 days, grouped into no (no days) and yes (1 to all 30 days). d) Family context: • Having meals with the family five or more days per week: the frequency in days that the adolescent usually has lunch or dinner with their mother, father, or guardian, classified as no (never, rarely, 1 to 3 times per week) and yes (5 to 6 times per week or every day); • Parents understand their problems: the frequency that parents or guardians understand the problems and concerns of their children, divided into two categories -no (never, rarely) and yes (sometimes, most of the time, always); • Family supervision: the frequency that parents or guardians actually know what their child is doing in their free time, categorized into -yes (sometimes, most of the time, always) and no (never, rarely).
We carried out a descriptive analysis and calculated the prevalence of the outcome violence against adolescents inflicted by an adult relative and its respective 95% confidence intervals (95%CI), according to sociodemographic characteristics, family context, lifestyles, and mental health. Subsequently, we calculated the crude odds ratio (OR) to estimate the relationships between explanatory variables and domestic violence, selecting the variables associated at the p<0.20 level for the multivariate multinomial logistic regression model, which, according to some authors, is the most commonly used to evaluate statistical associations when the outcome of interest has more than two categories 11 .
In the multivariate analysis, all variables were mutually adjusted, and the adjusted OR (ORa) for the frequency of domestic violence against adolescents was calculated. Only the variables statistically associated (p<0.05) remained in the final model. All analyses considered the sampling structure and post-stratification weights. Data were analyzed with the aid of the survey module of the Stata statistical package, version 13.
The National Research Ethics Committee (Comissão Nacional de Ética em Pesquisa -CONEP) of the National Health Council (NHC) approved PeNSE 2015 under CONEP Opinion 9 no. 1,006,467, on March 30, 2015. The students voluntarily participated in the survey and registered their agreement in the Informed Consent Form (ICF) present in the smartphone. The information refers only to students who agreed to participate in the research. The analyses conducted protected the anonymity of the students and schools 9 . The research followed recommendations from the Brazilian Child and Adolescent Statute, which ensures the autonomy of adolescents in participating in studies aimed at promoting policies to protect their health and that do not pose a risk to them 9 . Table 1 shows that the prevalence of adolescents aged 13 to 17 years who reported physical abuse by an adult relative was 13.3%, of which 5.7% (95%CI 5.1 -6.4) declared having experienced domestic violence once and 7.6% (95%CI 6.7 -8.5) more than once. Adolescents who experienced more than one episode of domestic violence were aged 13 to 15 years -8.6% (95%CI 7.6 -9.6), males -8.6% (95%CI 7.4 -10.0), had insomnia -13% (95%CI 11.0 -15.0), were victims of bullying -20% (95%CI 17.0 -23.0), smoked -21% (95%CI 17.0 -26.0), and consumed alcoholic beverages -12.5% (95%CI 10.8 -14.4) ( Table 1).

IV. Family context
Has meals with the family five or more days per week

DISCUSSION
Approximately one-tenth of adolescents reported being physically abused by an adult relative. Among them, about 70% had been victims more than once in the month prior to the survey. PeNSE shows that domestic violence against adolescents was associated with males, the younger age group, black and multiracial ethnicity, insomnia, victims of bullying, alcohol consumption, and smoking. Protective factors for physical abuse against adolescents included parents who understand their children's problems, family supervision, female gender, age between 16 and 17 years, and having mothers with complete higher education.
The literature suggests that older adolescents, aged 15 to 19 years, are more susceptible to street violence since they spend more time outside the home environment, while younger ones (10 to 14 years) and children are more vulnerable to domestic violence 12 . The study corroborates the protective role of the age group 15 to 19 years for domestic violence, even though they are more prone to street violence. In the relations of power and subordination within families, children and younger adolescents are more vulnerable to violent episodes from adults due to their greater physical and emotional fragility 13, 14 .
This research showed that female adolescents experienced less domestic violence than male ones. This information contradicts several studies that report that women of all age groups are the main victims of domestic violence 12,15 . However, some authors point out the influence of gender-related cultural factors on domestic violence and on the relationship between family members, given that violence against women is a multifactorial phenomenon, suggesting that further investigation is necessary in future studies [15][16][17][18][19] .
Adolescents whose mothers had completed higher education showed a lower prevalence of domestic violence. Some authors have identified that, in the group of children and adolescents victims of domestic violence, the prevalence of female and less educated aggressors was greater, and higher schooling reduced the chance of violence 15 . In addition, as women with less schooling have no knowledge about the development of children and adolescents and are victims of abuse by their partners, they reproduce punitive educational practices learned in the family and through culture, increasing the prevalence of domestic violence 15,18 .
Concerning the mental health characteristics investigated, insomnia or difficulty in sleeping and bullying increased the chances of adolescents experiencing domestic violence once and more than once. A study revealed that daily affective experiences were related to the quality of sleep among adolescents, with sleep deprivation or its reduced duration being contributing factors to the emergence of violent situations in this age group 19 . Sleep is also associated with bullying, and some authors indicate that adolescents victims of bullying have a higher chance of insomnia 20 . Therefore, the difficulty in sleeping can be a triggering or a resultant factor of violence, since it can affect the emotional state of the adolescent, leaving them incapable of dealing with stressful situations in the family, or reflect the troubled experiences in their routine. REV BRAS EPIDEMIOL 2020; 23: E200003.SUPL.1 Among the family factors, studies show that the violence experienced by adolescents in the home environment is associated with greater involvement of the student in acts of violence in school, either as victims or aggressors 12,20,21 . Victims of bullying are predominantly male, young, black, and their mothers have little or no schooling, revealing the influence of social context on the violence against adolescents 20,22 .
Black ethnicity was associated with episodes of domestic violence experienced by adolescents, corroborating other investigations 15,23 . Moreover, some authors point to greater involvement of black adolescents in the regular use of and experimentation with cigarettes and illicit drugs, as well as in physical fights, leading to a greater risk in situations of physical abuse, bullying, and domestic violence 20,23 .
Many studies have also indicated the association of smoking and alcohol consumption with domestic violence among adolescents 24,25 . On the one hand, the authors identified that adolescents consume alcoholic beverages as a way of relieving the stress and violence experienced in the family environment or coping with these situations 21 , in addition to being a means of socializing with other adolescents in parties and clubs 26 . On the other hand, the use of licit or illicit drugs brings adolescents closer to situations of violence 25 . In the family environment, the consumption of alcoholic beverages by parents and acquaintances in the presence of the students also contributes to the emergence of domestic violence [27][28][29] . Therefore, alcohol consumption among adolescents can be a cause or a consequence of domestic violence, and further studies are necessary to verify its causality with domestic violence in this age group 29 . Smoking also remained with high odds ratio among adolescents who experienced domestic violence more than once, agreeing with authors who found that domestic violence was one of the factors that increased the chances of students using tobacco products 24 .
According to the family context, the understanding of parents when faced with the problems and concerns of their adolescent children proved to be crucial in preventing various risk situations, including domestic violence. Family situations such as having meals with parents or guardians five or more days per week and parents who understand their children's problems were factors that decreased the chance of adolescents experiencing domestic violence.
According to the results found in this study, the protective factors for domestic violence are having a good relationship with parents, family habits such as having meals together, and parents knowing what the adolescents do in their free time 30,31 . Some authors argue that the formation of family ties through shared activities, such as talking and having meals with parents or guardians, reduces health risk behaviors among adolescents 32 . The harmonious coexistence between parents and their adolescent children also contributed to social relations, decreasing the risk of being a victim or perpetrator of bullying 20,22 .
Parental supervision of the activities of their children was associated with a lower chance of experiencing an episode of domestic violence in the month prior to the survey, while its relationship with experiencing it more than once was not significant. Studies show the protective role of parental supervision in preventing harmful habits to the health of adolescents, such as smoking and using other tobacco products, consuming alcoholic beverages, and using drugs, in addition to benefiting the social relation between students 24,31 , reducing the risk of being a victim or perpetrator of bullying 20,22 . In contrast, disrespecting the privacy of adolescents contributes to domestic abuse 32 .
Thus, we underline the multicausal nature of domestic violence, as a reflection of the dynamics of the relationship between parents and children, poverty, addiction to alcohol and other drugs, chronic diseases in the family 28 , low household income, low schooling, among other factors. These factors can also harm the psychosocial development of adolescents, contributing to the creation of a tense and stressful environment for adolescents and their families 8 .
Domestic violence against adolescents is related to social inequality, psychoactive substance use, and violence in the school environment. Bullying, smoking, and alcohol consumption increase the chance of adolescents experiencing an episode of domestic violence, while having more involved parents who understand their children's problems and know what they do in their free time reduces it. Consequently, reducing social and ethnic inequalities and investing in financial, social, and structural resources that foster harmonious family relationships can break the cycle of violence, providing better living conditions to the adolescent.
Since this study has a cross-sectional design, the results have limitations related to causality, showing only the existence of an association between these phenomena. In addition, the question included in the PeNSE questionnaire about domestic violence did not allow us to identify the aggressor and distinguish between the various forms of abuse experienced by the adolescent, be it moral, sexual, or psychological, that could interfere with the results presented herein.