Abstract
Growing evidence suggests that income inequality is associated with adolescent substance use behaviors, prompting the presumption that it may also be associated with poly-substance use. This study examined the association between income inequality and poly-substance use and tested whether anxiety indirectly affects this relationship. We used cross-sectional survey data from the 2018–2019 Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and Sedentary behavior (COMPASS) project. The analytical sample comprised 71,396 students from 136 secondary schools and 43 census divisions across four Canadian provinces. Using multilevel path analyses, we examined the direct and indirect association between income inequality and poly-substance use. Students in neighborhoods with moderate income inequality relative to those in low-income inequality neighborhoods had higher odds of poly-substance use, with similar odds observed for both females (ORmod = 1.34; 95% confidence interval [CI] = [1.02, 1.66]) and males (ORmod = 1.38; 95% CI = [1.05, 1.72]). In relation to the indirect association through anxiety, gender-stratified results showed that attending schools in neighborhoods with moderate- and high-income inequality was associated with slightly higher odds of poly-substance use among females (ORmod = 1.09; 95% CI = [1.01, 1.18] and ORhigh = 1.10; 95% CI = [1.00, 1.21]). Income inequality is associated with poly-substance use, and this relationship is also indirectly influenced by anxiety among females. Reducing neighborhood income inequality may contribute to lowering poly-substance use among adolescents. In addition, anxiety management in schools located in highly unequal neighborhoods may be an effective intervention approach in reducing poly-substance use among female adolescents.
Poly-substance use, defined as the use of more than one addictive substance, has become a common practice among substance users (Boileau-Falardeau et al., 2022; Czoli et al., 2023). Particular interest has been placed on adolescent poly-substance use (Zuckermann et al., 2019). In Canada, approximately 11% of adolescents (15–19 years) reported poly-substance use in 2020, with e-cigarettes, tobacco, cannabis, and alcohol being the most common substances used concurrently (Czoli et al., 2023). A surge in adolescent poly-substance use was also reported in a 2013–2018 longitudinal study, which found that 50% of adolescent substance users had transitioned to poly-substance use by 2018 (Zuckermann et al., 2019). This increase has been linked to e-cigarette development and cannabis legalization, as these have become the most commonly reported substances used among adolescents (Czoli et al., 2023; Zuckermann et al., 2019).
Adolescent poly-substance use has been identified as a life-course risk factor for the development of alcoholism, substance use disorder, and mental health disorders in adulthood (Conway et al., 2013; Czoli et al., 2023; Zuckermann et al., 2019, 2020). In addition, adolescent poly-substance users are at an increased risk of engaging in adverse risk behaviors above and beyond the risk conferred by the use of single substances. This includes violent crime, aggression, delinquency, and risky sexual behaviors that synergistically may lead to deleterious health outcomes (Connell et al., 2009; Morley et al., 2015; Zuckermann et al., 2019). Beyond the health effects, poly-substance use exerts social and economic toll on society due to costs associated with lost productivity, increased criminality, and higher health care spending (Moss et al., 2014). The economic burden of poly-substance use has not been extensively studied; however, in 2020, Canadian health care costs attributed to generalized substance use were $13.4 billion and lost productivity costs via death and disability due to substance use were $22.4 billion (Canadian Centre on Substance Use and Addiction, 2023). Therefore, addressing poly-substance use may lead to improved health outcomes and contribute to reduced economic burden.
Epidemiological research on adolescent poly-substance use is still in its infancy (Czoli et al., 2023). Overall, extant studies have shown that adolescents who are male, at a higher grade level, a racialized minority, have mental disorders, have higher amounts of spending money, participate in online gambling, and have strong peer support are more likely to report poly-substance use (Banks et al., 2017; Conway et al., 2013; Halladay et al., 2020; Schneider et al., 2020; Zuckermann et al., 2019, 2020). Conversely, adolescents who report having strong family and school support are less likely to report poly-substance use (Zuckermann et al., 2020). There has been a paucity of studies examining the association between area-level factors and adolescent poly-substance use, with limited evidence linking regions of residence (Zuckermann et al., 2020), low socioeconomic status (Halladay et al., 2020), poverty (Rose et al., 2018), and low social connectedness (White et al., 2015) with poly-substance use.
Income inequality refers to the unequal distribution of income across individuals or households within a geographical area (Subramanian & Kawachi, 2004). Income inequality, often measured using the Gini coefficient, highlights the disparity or the gap between the highest and the lowest income groups within a population (Pickett & Wilkinson, 2015). Beyond its economic implications, income inequality as a structural factor plays an essential role in shaping population health outcomes because it influences social determinants of health such as housing, education, employment, and access to health care resources (Kawachi & Kennedy, 1999; Pickett & Wilkinson, 2015; Subramanian & Kawachi, 2004). Few studies have examined the association between income inequality and substance use in general, with evidence suggesting an association between high income inequality and greater odds of cannabis use, daily e-cigarette use, and alcohol consumption (Benny et al., 2023; Lowe et al., 2023). Due to associations being identified with single-substance use, it can be postulated that living in highly unequal areas may be associated with poly-substance use. There are various mechanisms through which income inequality can influence health-related risk behaviors, including erosion of social cohesion and divestment in public infrastructure (Benny et al., 2023). However, the most plausible mechanism in relation to poly-substance use may be through the development of anxiety, which may arise as a consequence of invidious social comparisons, as areas with high income inequality tend to have more pronounced social hierarchies (Kawachi & Kennedy, 1999; Pickett & Wilkinson, 2010). It is hypothesized that feelings of inferiority based on perceptions of low socioeconomic standing in a community (i.e., having fewer goods than others; Kondo et al., 2015; Melita et al., 2023) can create negative emotions such as feelings of rejection, distrust, and shame (Layte, 2012; Wilkinson & Pickett, 2017). In turn, accompanying anxiety symptoms may lead to poly-substance use as a self-medication mechanism for mental distress (Turner et al., 2018).
Given that structural factors are the “root causes” of health inequities (Baciu et al., 2017), there is a need to better understand the mechanisms of income inequality and its impact on poly-substance use among adolescents. Providing such an understanding could contribute to the development of effective intervention strategies to reduce the harm associated with poly-substance use. Therefore, the current study intends to investigate the association between income inequality and poly-substance use empirically. Specifically, the study aims to (a) examine the relationship between census division (CD) income inequality and poly-substance use among Canadian secondary school students and (b) investigate whether the possible relationship between CD income inequality and poly-substance use is indirectly influenced by anxiety. We hypothesize that higher CD income inequality will be associated with higher odds of poly-substance use, and that this relationship will be indirectly influenced by anxiety.
Method
Data were drawn from Wave 7 (2018–2019) of the Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and Sedentary behavior (COMPASS) prospective cohort study, which included students between Grades 9 and 12 in Alberta, British Columbia, and Ontario, as well as Grades 7 and 11 in Quebec (Leatherdale et al., 2014). Schools were recruited for the COMPASS study through a convenience sampling approach based on the permitted use of active information–passive consent protocols (Hompson-Haile et al., 2013). All students enrolled in participating schools were eligible to participate if they were not withdrawn from the study by their parent/guardian. Participating students completed machine-readable questionnaires during class time.
The current cross-sectional study linked COMPASS study Wave 7 student-level data to the 2016 Canadian Census data at the CD level to obtain measures of income inequality and other covariates of interest. Only adolescents with complete data on the variables of interest were retained for analysis. Out of 74,501 students that participated in Wave 7 of the COMPASS study (~80% response rate), 71,396 (95.8%) adolescents from 136 schools and 43 CDs comprised our study sample. All COMPASS study protocols received ethics approval from the University of Waterloo Office of Research Ethics (#30118), University of Alberta Ethics (#RE0050375), and participating schools’ board committees (Leatherdale et al., 2014). Further details on the COMPASS study methods and protocols can be found online (www.uwaterloo.ca/compass-system/).
Outcome
Self-reported measures were used to assess participants’ usage of various substances (Elton-Marshall et al., 2011; Wong et al., 2012; Zuckermann et al., 2019). The study outcome was derived from participants’ responses on their usage of the following substances: cannabis, alcohol, and cigarettes. For cannabis and alcohol, participants reported their frequency of usage within the last 12 months with response options ranging from “never used” to “every day.” For cigarettes, participants reported their frequency of usage of combustible cigarettes and e-cigarettes within the last 30 days, with response options “never used” to “every day.” In line with previous research (Zuckermann et al., 2019), an indicator variable was created for each of the three substances, classifying participants as users if they indicated to have used cannabis and alcohol at least once a month and cigarettes and/or e-cigarettes at least once a day. The poly-substance use variable was then created by summing up the number of substances the participants reported using, with values ranging from 0 to 3. Poly-substance use was defined as the usage of two or three substances.
Exposure
Income inequality at the area level was measured using the Gini coefficient. The Gini coefficient was calculated at the CD level using after-tax income data derived from the 2016 Canadian Census. A detailed description of the calculation of the Gini coefficient is documented elsewhere (Dorfman, 1979). The Gini coefficient scores range from 0 (equal distribution) to 1 (unequal distribution). This coefficient was transformed into tertiles to better assess the hypothesized dose–response relationship.
Mediator
The Generalized Anxiety Disorder (GAD-7) scale, a 7-item scale that focuses on self-perceived feelings of irritability, worry, and fear within a period of 2 weeks was used to assess anxiety symptoms (Spitzer et al., 2006). Four response options for each item were “0 = not at all,” “1 = several days,” “2 = over half the days,” and “3 = nearly every day.” Scores across the seven items were combined to create a composite variable to assess anxiety. The total score ranged from 0 to 21, with a higher score indicative of more frequent anxiety symptoms. The internal consistency of the GAD-7 scale was 0.91.
Covariates
Participants were asked if they were female or male, and their response options were female or male. The item did not specify sex or gender. Evidence suggests that such survey responses may reflect either the biological (sex) or the social (gender) identity of the participants (Johnson et al., 2009). Since this study focused on structural inequities, we used the term gender rather than sex when referring to the covariate. Other covariates at the individual level included participants’ grade level (Grades 7–12/other), ethnicity (White or people of color), weekly spending money ($0/$1–$5/$6–$10/$11–$20/$21–$40/$41–$100/>$100/don’t know), participation in online gambling (yes/no/not stated), if participants would seek mental health support from adults in school (yes/no), if participants would talk to friends or family about their problems (yes/no/not stated), and if participants perceived their school as being supportive of their efforts to resist/quit drugs and/or alcohol (yes/no/not stated) (Zuckermann et al., 2019, 2020). After-tax median income, proportion of households living below low income cut-off and provinces were used as covariates at the CD level (White et al., 2015; Zuckermann et al., 2020).
Statistical Analysis
Descriptive statistics, including proportions and means for discrete and continuous variables, were used to examine the characteristics of the study population. Afterward, two-level path analysis models were used to investigate the hypothesized relationship between income inequality and poly-substance use. A multi-level approach was considered suitable for this study due to the hierarchical nature of the dataset, where students and schools were nested within CDs. The path analysis approach was selected because it allows for the modeling of a “chain of variables” acting on a specified outcome. This study used path analysis to obtain the direct and indirect association between income inequality and poly-substance use.
Data were cleaned using STATA v16.0, whereas path analysis was performed using MPLUS v8.8. The outcome was an ordinal variable with three levels: 0 (no substance use), 1 (single substance use), and 2+ (poly-substance use). The proportional odds model would be ideal to model our ordinal outcome; however, this approach proved unsuitable for this study since the proportional odds assumption was violated. We opted to conduct a series of probit regressions for our path analyses because it is suitable for binary outcomes that are not rare (B. Muthén et al., 2011; B. O. Muthén et al., 2017). Therefore, the outcome variable was split into two binary outcomes: (a) a comparison between no substance use versus poly-substance use and (b) a comparison between no substance use versus single substance use which served as a sensitivity analysis. Furthermore, gender-stratified models were fitted for each outcome to assess whether the association between income inequality and poly-substance use was heterogeneous among males and females. All models were fitted using the maximum likelihood robust (MLR) estimator (B. Muthén et al., 2011). Regression coefficients were converted to odds ratio (ORs) and interpreted at a 95% confidence level.
Assessing Model Fitness
Given the categorical outcome of our models, model fit indices available for probit regressions within a multilevel path framework are limited to likelihood ratio tests (nested models) and information criteria measure (non-nested models) (Curran et al., 2010). We used log-likelihood measures by comparing values of unadjusted path models (Model 1) to the fully adjusted path model (Model 2), with the models with a higher value indicating adequate fit.
Results
Descriptive Statistics
The study sample was balanced with 50% females and 50% males (Table 1). Nearly one half of the participants were either in Grade 9 (23.4%) or 10 (23.4%), whereas more than two thirds (69.5%) self-identified as White. Most participants reported having more than $100 in weekly spending money, with the proportion of males (20.7%) being slightly higher than that of females (17.5%). Approximately 90% of the participants did not participate in online gambling. More than half of the participants (54.9%) reported that they would not seek mental health support from adults in school. However, most of the participants (53.5%) acknowledged that the school was supportive of their need to resist/quit drugs. In terms of anxiety (GAD-7) scores, the mean for females (7.68, SD = 5.76) was higher than that for males (4.58, SD = 4.89).
Descriptive Characteristics of the Study Population from the COMPASS Study.
Substance Use Combinations
Among the three substances studied, alcohol (30.9%) was the most common substance used, whereas cannabis (12.9%) was the least common (Table 1). A quarter of the participants (22.5%) indicated that they used at least two substances, with 8.5% of the participants using all three substances. Among participants who reported using two substances, the most common combination was the concurrent use of cigarettes and alcohol (10.6%) (Supplemental Table S1, Supplemental material). Overall, the proportion of males (43.7%) using substances (1 or more) was slightly higher relative to females (40.1%), regardless of the combination of concurrent substance use.
Income Inequality and Poly-Substance Use
Log-likelihood values for the fully adjusted path models (females = −97,656.998 and males = −94,122.733) were higher compared with the unadjusted models (females = −99,524.018 and males = −97,219.206), indicating an adequate fit for our final models. Moderate income inequality was significantly associated with a higher risk of poly-substance use, with a slightly higher magnitude of association observed among males (βmod = 0.17; 95% CI = [0.04, 0.29]) relative to females (βmod = 0.16; 95% CI = [0.03, 0.30]) (Figure 1). This corresponded to 38% and 34% increases in the odds of poly-substance use among males (ORmod = 1.38; 95% CI = [1.05, 1.72]) and females (ORmod = 1.34; 95% CI = [1.02, 1.66]), respectively (Table 2). However, the stratified direct association between high-income inequality and poly-substance use was not significant for both females (ORhigh = 0.93; 95% CI = [0.67, 1.19]) and males (ORhigh = 1.05; 95% CI = [0.83, 1.27]).
Unstandardized Beta Coefficients of the Multilevel Path Analysis Models of Poly-Substance Use Stratified by Gender.
Multi-Level Path Analysis of Polysubstance Use (>2 vs. non-use) for all Adolescents Stratified by Gender.
Note. Models adjusted for grade, ethnicity, weekly spending money, online gambling, mental health support, family support, friend support, school support to resist drugs, province, median after tax income, and proportion of household below the low-income cut-off.
Results for gender-stratified indirect associations were also significant for both females and males (Figure 1). Relative to low-income inequality, females’ schooling in areas classified in the moderate and high tertiles of income inequality were associated with an increased risk of anxiety symptoms (βmod = 1.21; 95% CI = [0.15, 2.26]; βhigh = 1.27; 95% CI = [0.02, 2.52]). In turn, one unit increase in anxiety score was associated with a higher risk of poly-substance use among females (β = 0.04; 95% CI = [0.03, 0.05]). Similar patterns were also observed among males, where the risk of anxiety was higher for those schooling in areas with moderate (βmod = 0.49; 95% CI = [−0.14, 1.12]) and high (βmod = 0.51; 95% CI = [−0.22, 1.24]) income inequality, although these estimates were not statistically significant. A unit increase in anxiety score was also significantly associated with a higher risk of poly-substance use among males (β = 0.03; 95% CI = [0.02, 0.03]). In sum, income inequality was indirectly associated with higher odds of poly-substance use through anxiety, but this association appeared only for females attending schools in areas with moderate (ORmod = 1.09; 95% CI = [1.01, 1.18]) and high (ORhigh = 1.10; 95% CI = [1.00, 1.21]) income inequality (Table 2). Finally, it is important to highlight that both moderate and high levels of income inequality were more strongly associated with poly-substance use compared with single substance use (Supplemental Table S2 and Supplemental Figure S1 in the Supplemental material).
Discussion
In summary, this study found that many adolescents reported poly-substance use rather than single-substance use. Students schooling in areas with moderate income inequality had higher odds of poly-substance use, with a larger OR found in males. Contrary to our hypothesis, schooling in areas with high-income inequality was not significantly associated with higher odds of poly-substance use for both females and males. Finally, for females, schooling in moderate- and high-income inequality areas was associated with greater odds of poly-substance use, in part due to anxiety.
Structural characteristics of the schooling environment have been shown to play essential roles in adolescent substance use, for which income inequality is no exception. The erosion of social cohesion could be one of the mechanisms underlying the observed direct association between moderate income inequality and poly-substance use. Social cohesion is characterized by close relations, shared values, mutual trust, and a sense of belonging (Pei et al., 2020). Socially cohesive societies are known to provide safe environments for the upbringing of adolescents since more equal neighborhoods tend to experience high investments in public infrastructure and low levels of violent crime and illnesses (Kawachi & Berkman, 2014; Wilkinson & Pickett, 2017). In addition, there is a higher likelihood for community members to be engaged in adolescents’ lives, including supervision of their behaviors, guidance in decision-making, and assisting when they experience adverse life events (Hong et al., 2022; Pei et al., 2020). Erosion of social cohesion may lead to a deterioration of this collective efficacy; hence, adolescents are likely to receive minimal support when troubled. Adolescents may, thus, be engaged in poly-substance use as a coping mechanism to deal with stress/unhappiness and other problems associated with adolescence.
The seemingly null association of high-income inequality against poly-substance use is somewhat unexpected but not utterly surprising since some studies have found no associations (Gonzalez-Casanova et al., 2014; Lynch et al., 2004) and others have also reported high income inequality as a “protective factor” of some adverse health outcomes (Fan et al., 2016; Kim et al., 2018). A possible explanation for this association can be drawn from the mixed neighborhood hypothesis, which posits that living in neighborhoods with a balanced socio-economic mix may offer benefits to the socioeconomically disadvantaged in terms of access to quality services and local infrastructure that are available in the community as a result of investments and civic advocacy from the socioeconomic elites (Manley et al., 2011; Tibber et al., 2022). Therefore, high-income inequality neighborhoods may not necessarily be characterized by deprivation and social disorder that may stimulate poly-substance use, but instead may offer quality educational, economic, and recreational opportunities that cushion adolescents from engaging in deviant behaviors.
Besides the direct pathway, this study also suggests that income inequality may indirectly increase the odds of poly-substance use by increasing anxiety symptoms in female adolescents. Results call for confirmation in longitudinal designs. In highly unequal societies, the development of anxiety has been argued to be an offshoot of invidious social comparisons (Kawachi & Kennedy, 1999). Literature suggests that social hierarchies are more pronounced in areas characterized by high income inequalities (Pickett & Wilkinson, 2010), and inherently, adolescents would desire to seek status to gain respect, admiration and acceptance among their peers (Lansford et al., 2009; Magee & Galinsky, 2008). Even though higher social standing can positively boost one’s self-esteem and self-worth, the quest for higher status could be a source of chronic stress and anxiety since failure to achieve the “ideal standard” may be regarded as a sign of inferiority (Pickett & Wilkinson, 2010). Therefore, poly-substance use could result from a process of self-medication to mitigate the symptoms of anxiety and other mental health disturbances (Fergusson et al., 2011).
Taking into account both the direct and indirect associations, the relationship between income inequality and poly-substance use was notably stronger among female adolescents than their male counterparts. This finding comes with little surprise, as it resonates with existing research on gender differences in stress response, coping mechanisms, and substance disorder (Boyd, 2024; Keyes & Platt, 2024; Maxwell et al., 2022; McHugh et al., 2018). Female adolescents are known to be more vulnerable to mental illnesses, as studies have consistently shown that females report higher levels of mental health problems such as anxiety and depression (Figas et al., 2023; Panchal, 2024). Therefore, mental health distress, such as anxiety, can be amplified in females as a response to stressful environments in high income inequality areas (Bahrami & Yousefi, 2011). Since female adolescents are socialized to internalize stress compared with males (Keyes & Platt, 2024), poly-substance use may serve as a coping mechanism in stressful environments where other healthy coping mechanisms are unavailable or ineffective. In addition, evidence suggests that women may develop substance addiction more rapidly following initial exposure (Boyd, 2024; McHugh et al., 2018). As such, schooling in areas with high income inequality, characterized by weakened social cohesion, may elevate the risk of poly-substance use among adolescent females.
Analyzing adolescent data on poly-substance use reveals some crucial insights that could have critical implications for research and public health practice. Given that poly-substance use is the norm rather than the exception, we believe that research, treatment, and public health practice oriented toward poly-substance use would have a more significant impact on the prevention and management of substance abuse. While there is no “silver bullet” in addressing poly-substance use, our findings suggest that income inequality is one possible root cause for this problem. Therefore, upstream policies geared to alleviate neighborhood income inequality, such as progressive taxation and increasing education and economic opportunities for low income populations (Hoeller et al., 2014), may assist in obstructing multiple pathways through which income inequality increases the risk of poly-substance use. Besides reducing inequalities, schools located in unequal CDs could be targeted as venues for instituting public health interventions, including educational campaigns against substance use and support services for the rehabilitation of substance users. Strategies designed to mitigate poly-substance use should also reflect the different pathways through which income inequality leads to poly-substance use. For example, understanding that anxiety is a critical internalizing disorder that could elevate the risk of poly-substance use among females could necessitate integrating mental health treatment and substance abuse prevention strategies. Finally, our findings suggest that certain factors of high inequality neighborhoods could either deter or protect adolescents from engaging in poly-substance use. Even though creating mixed-income neighborhoods has been instituted in various countries, evidence of its usefulness in addressing deleterious health outcomes stemming from socioeconomic inequalities is highly controversial (Manley et al., 2011). Therefore, we opine that more research should be conducted on highly unequal neighborhoods to determine which aspects of these neighborhoods confer “protection” against poly-substance use.
This study has several limitations. First, this study was conducted using cross-sectional data, which limits the ability to precisely identify the temporal ordering of exposure and outcome variables. Even though path analysis can estimate the hypothesized relationships, the cross-sectional design limits the ability to infer a causal association. Second, COMPASS surveys utilize a convenience sampling procedure; therefore, our findings may have limited generalizability to the Canadian adolescent population. Third, substance use may have been underreported due to recall and social desirability biases. Furthermore, chronic school absenteeism has been associated with substance use (Gakh et al., 2020), which may result in an underestimation of poly-substance use in the study. Fourth, we could not differentiate between simultaneous (i.e., use of more than one substance in the same instance) and concurrent (i.e., use of more than one substance in a time period, such as the last 12 months) polysubstance use. Finally, despite the large sample size used in this study, we acknowledge our estimates might be biased due to missing data. To examine the potential of this bias, we conducted two diagnostic tests: (a) a chi-square test to examine the variations in missing data distribution by ethnicity, weekly spending money and province and (b) a logistic regression to examine the likelihood of non-response based on the same demographic characteristics. Results indicated that non-respondents were more likely to identify as a person of color, report low weekly spending money and attend school in Ontario or British Columbia. The overall differences in the proportion distribution between nonresponse and complete cases were modest, suggesting little impact of this bias on our findings.
In conclusion, our findings underscore the need for targeted interventions, as they suggest that income inequality is directly or indirectly associated with an elevated risk of poly-substance use among school-going adolescents. These results provide important insights into the influence of neighborhood factors on adolescent risk behaviors and further elucidate the mechanisms underlying such relationships. The challenge of targeted population interventions to mitigate poly-substance use among adolescents is pressing, and it should consider the differences in mechanisms through which income inequality influences high-risk behaviors.
Supplemental Material
sj-docx-1-heb-10.1177_10901981251389952 – Supplemental material for Untangling the Relationship Between Income Inequality and Poly-Substance Use Among Adolescents in Canada
Supplemental material, sj-docx-1-heb-10.1177_10901981251389952 for Untangling the Relationship Between Income Inequality and Poly-Substance Use Among Adolescents in Canada by Jason Mulimba Were, Amy B. Crandall-Nickolet, Karen A. Patte, Scott T. Leatherdale and Roman Pabayo in Health Education & Behavior
Footnotes
Acknowledgements
We would like to express our gratitude to the COMPASS study for providing access to the data that was used to conduct this study. Furthermore, we would like to acknowledge the University of Alberta for providing the library resources needed for the completion of this study. Finally, we would like to thank our colleague Kesia Muthuthotatil for her valuable assistance in generating and refining the figures used in this study.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The COMPASS study has been supported by a bridge grant from the CIHR Institute of Nutrition, Metabolism and Diabetes (INMD) through the “Obesity – Interventions to Prevent or Treat” priority funding awards (OOP-110788; awarded to SL), an operating grant from the CIHR Institute of Population and Public Health (IPPH) (MOP-114875; awarded to SL), a CIHR project grant (PJT-148562; awarded to SL), a CIHR bridge grant (PJT-149092; awarded to KP/SL), a CIHR project grant (PJT-159693; awarded to KP), and by a research funding arrangement with Health Canada (#1617-HQ-000012; contract awarded to SL), a CIHR-Canadian Centre on Substance Use and Addiction (CCSA) team grant (OF7 B1-PCPEGT 410-10-9633; awarded to SL), a project grant from the CIHR Institute of Population and Public Health (IPPH) (PJT180262; awarded to SL and KP). The COMPASS-Québec project additionally benefits from funding from the Ministère de la Santé et des Services sociaux of the province of Québec, and the Direction régionale de santé publique du CIUSSS de la Capitale-Nationale. RP is the Tier II Canada Research Chair in social and health inequities. KAP is the Canada Research Chair in Child Health Equity and Inclusion. JMW is supported by CIHR postdoctoral fellowship award (MFE-201020).
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
