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Abstract
Introduction In 2015, the elimination of hunger worldwide by 2030 was declared by the United Nations as a Sustainable Development Goal. However, food insecurity remains pervasive, contributing to socioeconomic health inequalities. The overall objective was to investigate the relationship between food insecurity and intentional injuries among adolescents.
Methods Individual-level data from the Global School-based Student Health Survey from 89 countries were used (370 719 adolescents, aged 12–17 years). Multilevel logistic regressions were used to examine the sex-specific association between the level of food insecurity (none, medium and high) and intentional injuries (interpersonal violence and suicide attempts), accounting for the clustering of observations within surveys. Random-effects meta-analyses were used to analyse dose–response relationships.
Results Medium and high food insecurity were associated with increased odds of reporting an injury from interpersonal violence among both sexes. A positive dose–response relationship was found, where each level increase in food insecurity was associated with a 30% increase in the odds of an injury due to interpersonal violence among boys (1.30; 95% CI 1.26 to 1.34) and a 50% increase among girls (1.53; 95% CI 1.46–1.62). The odds for suicide attempts increased by 30% for both sexes with each level increase in food insecurity (boys: 1.29; 95% CI 1.25–1.32; girls: 1.29; 95% CI 1.25–1.32).
Discussion The findings indicate that socioeconomic inequalities exist in the risk of intentional injuries among adolescents. Although additional studies are needed to establish causality, the present study suggests that the amelioration of food insecurity could have implications beyond the prevention of its direct consequences.
- violence
- suicide/self?harm
- adolescent
- global
- health disparities
- hierarchical models
Data availability statement
Data are available in a public, open access repository. All data included in the current study are available in public, open access repositories. GSHS data can be obtained from https://www.who.int/ncds/surveillance/gshs/country/en/. Sources for covariate data used in the statistical modeling are indicated in the manuscript.
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Introduction
In 2015, the United Nations General Assembly identified ‘Zero Hunger’—that is, the elimination of hunger—by 2030 as Goal 2 of the Sustainable Development Goals.1 The prevalence of food insecurity was recognised as a specific indicator for monitoring progress towards this goal (Indicator 2.1.2—Prevalence of moderate or severe food insecurity in the population, based on the Food Insecurity Experience Scale). However, in 2018, the number of people who did not have enough food increased, for the third year in a row, to an estimated 820 million people globally.2 Not only does a lack of food directly impact one’s health negatively,3 even resulting in death,4 but it has also been identified as a risk factor for intentional injuries such as interpersonal violence and suicide attempts.5 6
D’Souza and Jolliffe used nationally representative household survey data and geo-coded data on violent incidents and found a significant positive association between violent conflict and food insecurity in Afghanistan.7 The association between food insecurity and intentional injuries has also been established using individual-level data.8 Vaughn and colleagues9 recently found that experiencing frequent food insecurity during childhood was predictive of interpersonal violence later in life (OR 2.1; 95% CI 1.8–2.4), with greater odds for boys (2.7; 95% CI 2.2–3.5) than for girls (1.6; 95% CI 1.4–2.0). It has also been suggested that food insecurity is a risk factor for suicidality,10 with a study conducted in the USA finding that adolescents with insufficient food supply had 5.0 (95% CI 1.7–14.6) times higher odds of having attempted suicide.11 Similarly, a cohort study of female individuals in India found that those who had recently experienced hunger had twofold odds of attempting suicide (2.0; 95% CI 0.5–7.5) after adjusting for a number of demographic and psychosocial factors.12
Increased levels of emotional distress and social tension as a consequence of food insecurity, which in turn increase one’s motivation to engage in interpersonal conflict or self-harming behaviour, are one of the potential underlying pathways through which food insecurity increases the risk of injuries from interpersonal violence and self-harm.5 13 A potential biological pathway for the impact of food insecurity on interpersonal violence is the link between glucose and impulse control, with low glucose levels leading to impaired impulse control.14 15 Food insecurity has also been shown to be a risk factor for mental distress and mental health problems,16–19 which, in turn, are related to an increased risk of suicidal behaviour.20
Evidently, the effects of hunger and food insecurity are likely to go above and beyond their direct consequences (eg, malnutrition and insufficient weight). Accordingly, when assessing the positive effects of eliminating hunger throughout the world, it is imperative that their indirect consequences, such as intentional injuries, are also considered, with risk establishment being the first step in determining such repercussions. Furthermore, death from an intentional injury, that is death from interpersonal violence or death by suicide (intentional self-harm causing death), is a major cause of mortality among adolescents throughout the world.21 In fact, intentional injuries are one of the leading causes of death among adolescents, accounting for 7% (10–14 years of age) and 14% (15–19 years of age) of all deaths among adolescents globally.21
Analysing individual-level data of more than 370 000 adolescents from 89 countries, this study investigated (1) the sex-specific risk of intentional injuries (ie, interpersonal violence and suicide attempts) related to food insecurity among adolescents, (2) the heterogeneity in the respective relationships in relation to country-specific characteristics (eg, country-income level), and (3) the sex-specific dose–response relationship between food insecurity and intentional injuries.
Methods
This study fully adheres to the Guidelines for Accurate and Transparent Health Estimates Reporting statement (online supplemental table S1).
Supplemental material
Data
Individual-level data were obtained from the Global School-based Student Health Survey (GSHS) for 113 surveys conducted between 2003 and 2015 in 89 countries (online supplemental table S3), translated to each respective countries’ main language(s). A standardised two-stage probability sampling design of students in grades 9–12 was used within each participating country (with slight variations in the definition of grades by country). In some countries (British Virgin Islands, Cayman Islands, Cook Islands (2011), Niue, Saint Kitts and Nevis and Tuvalu), the schools were selected based on a census approach. Due to low cell counts, the extreme age groups—that is, <12 and >17 years of age—were excluded from the current analyses. Observations with missing information on sex or food insecurity were also excluded (1.9% of the observations). In some countries, the survey was not nationally representative, but rather was regionally confined (Tanzania (Dar Es Salaam), 2006; China (Beijing), 2003; Ecuador (Quito), 2007; Palestine (West Bank), 2010; Chile (Metropolitan Region), 2004; Colombia (Bogotá), 2007; and Venezuela (Lara), 2003). The final sample comprised 370 719 adolescents (177 092 boys and 193 627 girls) aged 12–17 years.
The following country-level indicators were obtained from the World Bank for each country and year in which the surveys were conducted: gross domestic product and country-income level (available for 109 surveys (86 countries)), income inequality (Gini index; available for 84 surveys (67 countries)) and the proportion of the population living in rural areas (available for all 113 surveys).22 Population statistics were obtained from the United Nations.23
Measures
Food insecurity was assessed through the question ‘During the past 30 days, how often did you go hungry because there was not enough food in your home?’ and categorised into the following three categories: no food insecurity (‘never’), medium food insecurity (‘rarely’ or ‘sometimes’) and high food insecurity (‘most of the time’ or ‘always’).
In all countries, injuries from interpersonal violence were based on the respondents reporting ‘I was attacked or abused or was fighting with someone’ as the major cause of their most serious injury in the past 12 months. It should be noted that this question did not allow for a distinction between victims and perpetrators. Injuries from interpersonal violence were assessed in 98 of the surveys (78 countries). Suicide attempts were ascertained by asking participants in all countries ‘During the past 12 months, how many times did you actually attempt suicide?’, which was, for the purposes of this study, dichotomised (none vs at least one time). Suicide attempts were assessed in 54 of the surveys (51 countries).
Statistical analyses
We then quantified the association between the level of food insecurity (ie, no, medium and high food insecurity) and intentional injuries (two outcomes: interpersonal violence and suicide attempts) using multilevel logistic regression models, accounting for clustering of observations within surveys. We considered several potential country-level confounders with sufficient evidence of being related to the prevalence of either food insecurity or intentional injuries, including gross domestic product and country-income level, Gini index, proportion of the rural population in the country, WHO region and the year of the survey. A backward selection process was used24 25 to identify the relevant confounders of the relationship of primary interest as described by Aneshensel.26 A change of more than 10% in the regression coefficient relating to food insecurity was used as a criterion to retain a covariable in the final model.24 25 All analyses were adjusted for age and stratified by sex. Heterogeneity of the association between food insecurity and intentional injuries was then assessed by including an interaction term for food insecurity and country-income level, Gini index and WHO region. Survey weights were used in all analyses, including multilevel regression models. The estimated variance, and thereby the SE, was calculated based on the variation between primary sampling units and within each stratum. Consequently, CIs were not computed for countries where a census approach was.
In a second step, the dose–response relationship between food insecurity and each of the two outcomes among adolescents was assessed. Dose–response meta-analyses were based on survey-specific ORs of pairwise comparisons using the original five categories of food insecurity, estimated using logistic regression for each survey, adjusting for age and stratified by sex. First, bubble plots were used to determine if a linear model would be appropriate. Then, one-stage dose–response random-effects meta-analyses via restricted maximum likelihood were used to quantify the dose–response relationships.27 28
All statistical analyses were conducted using STATA V.15.1.29 The source code can be obtained from the authors on request.
Ethics statement
Ethics approval was not required as all statistical procedures were based on secondary data analyses, and all empirical work was conducted in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) and approval of ethics commissions in respective countries was obtained.
Results
The prevalence of high food insecurity was the highest in low-income countries (LICs), where more than 10% of both boys and girls experienced food insecurity in the past 30 days ‘most of the time’ or ‘always’. Even in high-income countries (HICs) where the prevalence of food insecurity was the lowest, around 7% of adolescents experienced high food insecurity in the past 30 days. The prevalence of high food insecurity among both sexes by country is shown in figure 1.
The prevalence of high food insecurity (going hungry ‘most of the time’ or ‘always’ during the past 30 days) among adolescents aged 12–17 years in 89 countries.
Overall, the prevalence of injuries from interpersonal violence was higher among boys across all country-income levels, ranging from 3.4% (95% CI 3.1%–3.7%) in lower-middle-income countries (LMICs) to 3.7% in HICs (95% CI 3.2%–4.1%); among girls, it ranged from 1.6% in upper-middle-income countries (UMICs; 95% CI 1.4%–1.7%) to 2.6% in LICs(95% CI 2.1% –3.1%). For both sexes, the prevalence of suicide attempts was above 10% across all country-income levels, with the highest prevalence at around 20% observed in LMICs. The average prevalence of food insecurity and intentional injuries by country-income level and sex is presented in the online supplemental table S2. Country-specific prevalence estimates are presented in the online supplemental table S3, and country- and sex-specific estimates are presented as the online supplemental tables S4 and S5.
The association between food insecurity and intentional injuries
Multilevel logistic regression models showed higher odds of both outcomes for higher levels of food insecurity. Results from the sex-specific multilevel logistic regression models on the association between food insecurity and injuries from interpersonal violence are presented in table 1. After applying the backward selection of confounding variables, regression models were adjusted for age only as no other variable changed the relationship between food insecurity and either of the outcomes by more than 10%. Medium and high food insecurity were associated with increased odds of reporting an injury from interpersonal violence among both sexes, with higher ORs among girls.
ORs for the association between food insecurity and (a) injuries from interpersonal violence and (b) suicide attempts adjusted for age
Heterogeneity in the ORs for food insecurity and both outcomes was investigated by sex and for the country-income level, Gini index and WHO region using interaction terms. For girls, ORs did not differ considerably by country-income level, Gini index and WHO region. However, a statistically significant interaction term was found for boys where the ORs differed by country-income level. Results from the analyses stratified by country-income level are shown in table 2. Among both sexes, the odds of experiencing interpersonal violence or at least one suicide attempt related to high food insecurity were highest in UMICs. The odds related to medium food insecurity did not differ considerably across the country-income levels for either outcome.
Hierarchical logistic regression models with a random intercept (survey) stratified by income level and sex, adjusted for age
Dose–response relationships
A dose–response relationship was confirmed a positive linear relationship for both outcomes for both sexes (figures 2 and 3) via random-effects dose–response meta-regression. Among boys, each level increase in food insecurity was associated with a 30% increase in the odds of an injury due to interpersonal violence (1.30 95% CI 1.26–1.34; based on 344 point estimates from 96 surveys), whereas among girls, the odds increased by more than 50% at each level (1.53; 95% CI 1.46–1.62; based on 277 point estimates from 92 surveys).
Dose–response random-effects meta-analyses for the level of food insecurity and the odds of reporting an injury from interpersonal violence among boys (left) and girls (right). Food insecurity was assessed via the question ‘During the past 30 days, how often did you go hungry because there was not enough food in your home?’.
Dose–response random-effects meta-analyses for the level of food insecurity and the odds of reporting a suicide attempt among boys (left) and girls (right). Food insecurity was assessed via the question ‘During the past 30 days, how often did you go hungry because there was not enough food in your home?’.
Similarly, a dose–response relationship was found for suicide attempts (boys: 1.29, 95% CI 1.25–1.32; based on 213 point estimates from 54 surveys; girls: 1.29, 95% CI 1.25–1.32; based on 211 point estimates from 54 surveys) indicating a 30% increase in the odds of a suicide attempt with each level increase in food insecurity (figure 3).
Discussion
Although eliminating food insecurity globally has received much attention,1 it not only remains prevalent but is, in fact, on the rise also.2 We found that among adolescents, food insecurity is pervasive across all country-income levels. Both the World Food Programme30 and the World Development Report31 have identified a reduction of food insecurity as a potential mechanism to reduce and prevent intentional injuries, namely interpersonal violence, on the country level. However, food insecurity has been largely overlooked in the global research arena as a potential risk factor for intentional injuries, a leading cause of death among adolescents.
Our study found elevated risks of intentional injuries among adolescents, with increases found for each level of food insecurity. The risks of experiencing interpersonal violence and at least one suicide attempt related to high food insecurity were greater in UMIC. Furthermore, the risk of experiencing interpersonal violence related to food insecurity was higher among girls compared with boys.
Although future longitudinal studies are needed, the relationship is supported by the literature on the relationship between food insecurity and childhood mental health (for intentional self-harm as the outcome). In a prospective study conducted among children, Slopen and colleagues found that persistent food insecurity was associated with both internalising and externalising problems at follow-up, independent of problem status at baseline.32 Consistent with studies on food insecurity and mental health or behavioural problems,18 33 the dose–response analyses showed a positive linear relationship for both outcomes.
The relationship between food insecurity and injuries from interpersonal violence was stronger among girls as compared with boys in general. This sex difference is the opposite of that reported by Vaughn and colleagues,9 who found greater odds of being a perpetrator of interpersonal violence later in life when frequent food insecurity during childhood was reported for boys than for girls. This could be due to differences in study design; however, it is not possible to determine if those reporting injuries from interpersonal violence were perpetrators or victims in the data used in this study. It is possible that the two roles could show very different associations with food insecurity among the two sexes.
Strengths and limitations
This is the first multicountry study to investigate food insecurity as a potential risk factor for two categories of intentional injuries among adolescents by sex and the first to explore the existence of dose–response relationships. However, there are a few limitations that should be acknowledged. First, this is a cross-sectional study and as such, casual inferences are precluded from this type of study design. Thus, causality needs to be determined and, in fact, bidirectional causation should be explored, as food insecurity is more likely in a context with violent conflict.34 35 Another possibility is that the relationship between food insecurity and intentional injuries can be explained by a shared risk factor such as depression, parental mental health status, and household income or wealth. However, it was not possible to control for these potentially important factors as there are no measures available in the GSHS. Second, it should be noted that food insecurity only captures an aspect of socioeconomic status (SES). However, the usual measures of SES (level of education, occupation and income) were not applicable as self-report measures of SES for children and adolescents.36 Finally, it should be noted that in 7 out of 113 surveys regional, rather than nationally representative, data were available. In these cases, country-level covariates were used as a proxy.
Conclusions
Importantly, our findings of the relationship between food insecurity and intentional injuries among adolescents suggest that there are socioeconomic inequalities in the risk for intentional injuries, at the individual level. Thus, a reduction in intentional injuries is a potential health benefit of ameliorating food insecurity, which suggests that the elimination of food insecurity worldwide could have implications far beyond the prevention of its direct consequences (eg, starvation, malnutrition and growth deficiencies). As recommended by Marmot,37 an upstream approach to prevention should be taken—that is to say, initiatives targeting food insecurity as well as the causes thereof (eg, climate change, income inequalities and conflict) can lead to a broad range of positive consequences downstream. As such, multisectoral policies to support sustainable agricultural production, to ensure universal access to health and education and to address existing inequalities at all levels should be prioritised in the global and national agendas.2 Such a global approach is particularly emphasised by Ingram and colleagues: ‘While the association of violence with food is not new […] the combined effects of globalization and global environmental change within relatively inflexible or inadequate institutional frameworks now highlights food-related violence as a potential rising concern of this century’.38 This study is intended to shed light on the importance of food insecurity with regard to its risk for intentional injuries among adolescents and reinforce the urgency for the elimination of hunger to all relevant levels of government globally.
What this study adds
This is the first multicountry study to investigate food insecurity as a potential contributor to intentional injuries among adolescents by sex.
There was evidence that a dose–response relationship between food insecurity and both categories of intentional injury exists for both sexes, with a higher risk of injury from interpersonal violence related to increasing levels of food insecurity found for girls.
This study identified heterogeneity in the relationship between food insecurity and intentional injuries with the highest risks found for upper-middle-income countries.
What is already known on the subject
Food insecurity is an important socioeconomic marker, which despite global efforts, remains highly prevalent in many low-income and middle-income countries.
Previous quantitative (longitudinal and cross-sectional) and qualitative studies have shown that food insecurity is associated with intentional injuries.
The sex-specific and dose–response relationship between food insecurity and two categories of intentional injuries—interpersonal violence and suicide attempts—remains unclear.
Data availability statement
Data are available in a public, open access repository. All data included in the current study are available in public, open access repositories. GSHS data can be obtained from https://www.who.int/ncds/surveillance/gshs/country/en/. Sources for covariate data used in the statistical modeling are indicated in the manuscript.
Ethics statements
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
Contributors CP had full access to all of the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis. CP, CK, JR and SL conceptualised and designed the study. AK generated the GSHS dataset and CK prepared the covariable dataset. CP, SL and JR determined appropriate statistical procedures. CK and CP performed the data analyses and statistical modelling. CP, SL, AK, AFC and JR contributed to data interpretation. CP, CK and SL wrote the first draft of the manuscript. All authors contributed to the writing and revision of the manuscript and approved of the final version to be published.
Funding This study was funded by Centre for Addiction and Mental Health.
Disclaimer The study sponsor had no impact on study design, data collection, data analysis, interpretation of data, writing of the report, or in the decision to submit the paper for publication. The corresponding author had full access to all the data in the study and final responsibility for the decision to submit for publication.
Map disclaimer The depiction of boundaries on this map does not imply the expression of any opinion whatsoever on the part of BMJ (or any member of its group) concerning the legal status of any country, territory, jurisdiction or area or of its authorities. This map is provided without any warranty of any kind, either express or implied.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.