Changing eating to manage weight or shape: A cross-sectional and prospective study of the prevalence and correlates in a large Canadian adolescent cohort.

OBJECTIVE: The present study examined reports of changing eating to manage weight/shape over one year among adolescents. It also tested how changing eating for weight/shape was associated with physical activity (resistance training, moderate-to-vigorous physical activity; MVPA) and mental health (depressive symptoms, flourishing), and whether weight perceptions moderated these associations. METHODS: Participants were Canadian adolescents (N = 20,614, Mage ± SD = 14.4 ± 1.3, 52.9% girls) who completed self-report surveys in the 2020-2021 and 2021-2022 waves of the COMPASS study. Separate multilevel models were tested for each outcome. RESULTS: Approximately 30% of adolescents reported changing their eating to manage weight/shape at least once a week. More days of changing eating were associated with significantly higher depressive symptoms and lower flourishing cross-sectionally (b = 0.51, b = -0.27) and over time (b = 0.35, -0.20); the flourishing association over time was weaker for adolescents who perceived themselves as overweight relative to about right. More days of changing eating were also associated with more MVPA and resistance training cross-sectionally (b = 2.81, b = 0.19) and over time (b = 1.28, b = 10). The relationship between changing eating and MVPA over time was stronger for adolescents who perceived themselves as overweight relative to about right; whereas the cross-sectional relationship between changing eating and resistance training was weaker. CONCLUSIONS: Reports of changing eating to manage weight/shape were associated with divergent health outcomes; research into how and to what extreme adolescents are changing eating to manage weight/shape, and identity factors that may contribute to these differences, is warranted.

Attitudes, subjective norms and perceived behavioural control factors influencing Canadian secondary school students' milk and milk alternatives consumption.

OBJECTIVE: The research objectives were to evaluate factors that influence Canadian secondary school students' milk and milk alternatives (MMA) consumption and to explore associations through age and gender lenses. DESIGN: A qualitative design was used, consisting of semi-structured interviews and photo-elicitation methods. Analysis was guided by the Theory of Planned Behaviour (TPB). Deductive and inductive thematic analyses were used to generate themes, charting data based on attributes such as gender and age. SETTING: Interviews were held virtually or via telephone. PARTICIPANTS: Participants were twenty-eight high school students from Ontario, Canada, diverse in terms of gender and age. RESULTS: Both desirable and undesirable beliefs about the health outcomes of consuming MMA were commonly discussed. These included health benefits such as strong bones, muscular strength, and growth, and health consequences like unwanted skin conditions, weight gain, and diseases. While boys and girls associated MMA consumption with muscular strength, boys predominantly considered this favourable, while girls discussed outcomes like unwanted skin conditions and weight gain more often. Adolescents' perspectives on taste/perceived enjoyment, environmentally friendly choices and animal welfare also influenced their MMA preferences. Parental influences were most cited among social factors, which appeared to be stronger during early adolescence. Factors involving cost, time and accessibility affected adolescents' beliefs about how difficult it was to consume MMA. CONCLUSIONS: Recommendations for shifting attitudes towards MMA are provided to address unfavourable beliefs towards these products. Interventions to increase MMA consumption among adolescents should include parents and address cost barriers.

Identifying latent classes of physical activity profiles over time among adolescents in Ontario, Canada.

BACKGROUND: Physical activity behaviours are known to be highly correlated. Adolescents who participate in one type of physical activity (e.g., physical education) have a greater likelihood of participating in other physical activities (e.g., organized sports); however, little research has examined participation rates in various physical activity behaviours concurrently. This study identified longitudinal physical activity profiles among secondary school aged youth in Ontario, Canada. METHODS: We used data from the COMPASS Study, a school-based prospective cohort study of adolescents in Canada. Using a repeated measures latent class analysis, Ontario students who participated in grade 9 PE in 2015-16 were analysed through to 2018-19 (n = 1,917). Latent classes were defined by: PE participation, guideline adherence (≥ 60 min/day of moderate to vigorous activity over the last 7 days), and sport participation (varsity, community, and/or intramural). Multinomial logistic regression models were used to examine associations between latent class membership and student characteristics. RESULTS: Three distinct latent classes were identified for females and four were identified for males. These classes were: (1) Guidelines (high probability of guideline adherence; females: 44%; males: 16%), (2) PE & Sports (high probability of PE and sport participation; females: 33%; males: 43%), (3) Guidelines & Sports (high probability of guideline adherence and sport participation; females: 23%; males: 23%;), and (4) Inactive (low probability of all physical activity indicators; males: 18%). Strength training, sleep, and English grade were associated with class membership among females. Ethno-racial identity, weekly spending money, strength training, and English and math grades were associated with class membership among males. CONCLUSIONS: Findings suggest that latent physical activity profiles differ by sex. Guideline adherence was the most common class among females, indicating high levels of independent physical activity, whereas PE & Sport participation was the most common class among males, indicating greater tendency towards organized activities. Additionally, a substantial number of male students were not engaging in any physical activity. Participation in both PE and sports did not necessarily lead to meeting physical activity guidelines, highlighting that these activities alone may not be providing sufficient levels of physical activity that align with current recommendations for Canadian youth.

Do sociodemographic risk profiles for adolescents engaging in weekly e-cigarette, cigarette, and dual product use differ?

BACKGROUND: E-cigarette use represents a contemporary mode of nicotine product use that may be changing the risk profile of participating adolescents. Understanding differences in sociodemographic characteristics of adolescents engaging in contemporary e-cigarette use and traditional cigarette use is important for effectively developing and targeting public health intervention programs. The objective of this study was to identify and compare sociodemographic risk profiles for exclusive e-cigarette use and dual-product use among a large sample of Canadian youth. METHODS: A survey of 46,666 secondary school students in the 2021-22 wave of the COMPASS study measured frequency of past month e-cigarette and cigarette use as well as age, sex, gender, racial or ethnic background, spending money, relative family affluence, and having one's own bedroom. Rates of cigarette-only, e-cigarette-only, and dual product use were calculated, and separate classification trees were run using the CART algorithm to identify sociodemographic risk profiles for weekly dual-product use and weekly e-cigarette-only use. RESULTS: Over 13% of adolescents used only e-cigarettes at least weekly, 3% engaged in weekly dual e-cigarette and cigarette use, and less than 0.5% used only cigarettes. Available spending money was a common predictor of dual-product and e-cigarette-only use. Gender diverse youth and youth with lower perceived family affluence were at higher risk for dual-product use, while white and multiethnic adolescents were at greater risk of e-cigarette-only use. Two high-risk profiles were identified for e-cigarette-only use and four high-risk profiles were identified for dual product use. CONCLUSIONS: This study used a novel modelling approach (CART) to identify combinations of sociodemographic characteristics that profile high-risk groups for exclusive e-cigarette and dual-product use. Unique risk profiles were identified, suggesting that e-cigarettes are attracting new demographics of adolescents who have not previously been considered as high-risk for traditional cigarette use.

Using random forest to identify correlates of depression symptoms among adolescents.

PURPOSE: Adolescent depression is a significant public health concern, and studying its multifaceted factors using traditional methods possess challenges. This study employs random forest (RF) algorithms to determine factors predicting adolescent depression scores. METHODS: This study utilized self-reported survey data from 56,008 Canadian students (grades 7-12) attending 182 schools during the 2021/22 academic year. RF algorithms were applied to identify the correlates of (i) depression scores (CESD-R-10) and (ii) presence of clinically relevant depression (CESD-R-10 ≥ 10). RESULTS: RF achieved a 71% explained variance, accurately predicting depression scores within a 3.40 unit margin. The top 10 correlates identified by RF included other measures of mental health (anxiety symptoms, flourishing, emotional dysregulation), home life (excessive parental expectations, happy home life, ability to talk to family), school connectedness, sleep duration, and gender. In predicting clinically relevant depression, the algorithm showed 84% accuracy, 0.89 sensitivity, and 0.79 AUROC, aligning closely with the correlates identified for depression score. CONCLUSION: This study highlights RF's utility in identifying important correlates of adolescent depressive symptoms. RF's natural hierarchy offers an advantage over traditional methods. The findings underscore the importance and additional potential of sleep health promotion and school belonging initiatives in preventing adolescent depression.

School learning modes during the COVID-19 response and pre- to during pandemic mental health changes in a prospective cohort of Canadian adolescents.

PURPOSE: Considerable debate centered on the impact of school closures and shifts to virtual learning on adolescent mental health during the COVID-19 pandemic. We evaluated whether mental health changes differed by school learning modes during the pandemic response among Canadian adolescents and whether associations varied by gender and perceived home life. METHODS: We used prospective survey data from 7270 adolescents attending 41 Canadian secondary schools. Conditional change linear mixed effects models were used to examine learning mode (virtual optional, virtual mandated, in-person, and blended) as a predictor of change in mental health scores (depression [Centre for Epidemiologic Studies - Depression], anxiety [Generalized Anxiety Disorder-7], and psychosocial well-being [Flourishing scale]), adjusting for baseline mental health and covariates. Gender and home life happiness were tested as moderators. Least square means were calculated across interaction groups. RESULTS: Students learning in a blended learning mode had greater anxiety increases relative to their peers in other learning modes. Females learning fully in-person and males learning virtually when optional reported less of an increase in depression scores relative to their gender counterparts in other learning modes. Learning virtually when optional was associated with greater declines in psychosocial well-being in students without happy home lives relative to other learning modes. CONCLUSION: Findings demonstrate the importance of considering gender and home environments as determinants of mental health over the pandemic response and when considering alternative learning modes. Further research is advised before implementing virtual and blended learning modes. Potential risks and benefits must be weighed in the context of a pandemic.

Factors associated with prospective changes in weight control intentions among adolescents.

INTRODUCTION: The present study examined predictors of negative changes in weight control intentions from before to during the COVID-19 pandemic among adolescents. METHODS: Participants were Canadian secondary school students enrolled in the COMPASS study and had completed self-report surveys before (T1; 2018/2019 and/or 2019/2020 school year) and during (T2; 2020/2021 and/or 2021/2022) the COVID-19 pandemic (N = 11,869, Mage ± SD = 13.79 years old ± 1.15, 52.89% girls, 45.30% boys, 1.81% gender diverse). Demographic, interpersonal, behavioral, and psychological predictors of weight control intention change from T1 (stay the same weight, not doing anything about weight) to T2 (lose weight, gain weight) were tested using multilevel logistic regressions. RESULTS: Over one-third (37.0%) of adolescents who reported wanting to stay the same weight at T1 changed their intention to lose or gain weight at T2, as did 28.5% of adolescents who reported not wanting to do anything about their weight at T1. Changing weight control intention from "not doing anything about weight" at T1 to weight gain/loss at T2 was associated with resistance training, emotion dysregulation, bullying, social media use, and gender. Changing weight control intention from "stay the same weight" at T1 to weight gain/loss at T2 was associated with gender, perceived financial comfort, social media use, and flourishing. CONCLUSIONS: Results highlight the prevalence of maladaptive weight control intention changes among adolescents, and elucidate related behavioral, interpersonal, demographic, and psychological factors. Findings can inform targeted intervention and prevention strategies to disrupt maladaptive changes in weight control intentions among high-risk subgroups.

Income Inequality and the Odds of Online Gambling Among a Large Sample of Adolescents in Canada.

Consistent evidence points to the detrimental effects of income inequality on population health. Income inequality may be associated with online gambling, which is of concern since gambling is a risk factor for adverse mental health conditions, such as depression and suicide ideation. Thus, the overall objective of this study is to study the role of income inequality on the odds of participating in online gambling. Data from 74,501 students attending 136 schools participating in the 2018/2019 Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and Sedentary behaviour (COMPASS) survey were used. The Gini coefficient was calculated based on school census divisions (CD) using the Canada 2016 Census linked with student data. We used multilevel modeling to explore the association between income inequality and self-reported participation in online gambling in the last 30 days, while controlling for individual- and area-level characteristics. We examined whether mental health (depressive and anxiety symptoms, psychosocial wellbeing), school connectedness, and access to mental health programs mediate this relationship. Adjusted analysis indicated that a standardized deviation (SD) unit increase in Gini coefficient (OR = 1.17, 95% CI 1.05, 1.30) was associated with increased odds of participating in online gambling. When stratified by gender, the association was significant only among males (OR = 1.12, 95% CI 1.03, 1.22). The relationship between higher income inequality and greater odds for online gambling may be mediated by depressive and anxiety symptoms, psychosocial well-being, and school connectedness. Evidence points to further health consequences, such as online gambling participation, stemming from exposure to income inequality.

The impact of 12 modifiable lifestyle behaviours on depressive and anxiety symptoms in middle adolescence: prospective analyses of the Canadian longitudinal COMPASS study.

BACKGROUND: Unhealthy lifestyle behaviours are becoming increasingly common and might contribute to the growing burden of mental disorders in adolescence. We examined the associations between a comprehensive set of lifestyle behaviours and depression and anxiety in middle adolescents. METHODS: School-based survey responses were collected from 24,274 Canadian high school students at baseline and 1-year follow-up (average age 14.8 and 15.8 years, respectively). Using linear mixed-effects models, we examined prospective associations of adherence to recommendations for vegetables and fruit, grains, milk and alternatives, meat and alternatives, sugar-sweetened beverages [SSB], physical activity, screen time, sleep, and no use of tobacco, e-cigarettes, cannabis, and binge drinking at baseline with the depressive and anxiety symptoms (measured by CESD-R-10 and GAD-7 scales, respectively) at follow-up. RESULTS: Adherence to recommendations was low overall, particularly for vegetables and fruit (3.9%), grains (4.5%), and screen time (4.9%). Students adhering to individual recommendations, particularly for meat and alternatives, SSB, screen time, sleep, and no cannabis use, at baseline had lower CESD-R-10 and GAD-7 scores at follow-up. Adhering to every additional recommendation was associated with lower CESD-R-10 (ß=-0.15, 95% CI -0.18, -0.11) and GAD-7 scores (ß=-0.10, 95% CI -0.14, -0.07) at follow-up. Assuming cumulative impact, this might translate into 7.2- and 4.8-point lower CESD-R-10 and GAD-7 scores, respectively, among students adhering to 12 vs. 0 recommendations over four years of high school. CONCLUSIONS: The results highlight the preventive potential of population-based approaches promoting healthy lifestyle behaviours, particularly those with the lowest prevalence, as a strategy to improve mental health in adolescence.

The intersection of internalizing symptoms and alcohol use during the COVID-19 pandemic: A prospective cohort study.

Given the well-established relationship between alcohol and internalizing symptoms, potential increases in depression and anxiety during the COVID-19 pandemic may lead to increases in alcohol consumption and binge drinking. This study examines this association from before to during two phases of the pandemic in a cohort of Canadian youth. We used linked data from a sub-sample of 1901 secondary school students who participated in three consecutive school years of the Cannabis use, Obesity, Mental health, Physical activity, Alcohol use, Smoking, and Sedentary behaviour (COMPASS) study between 2018/19 and 2020/21. Separate multilevel logistic regression models examined the association between depression and anxiety symptoms with odds of escalation and reduction (vs. maintenance) and initiation (vs. abstinence) of alcohol consumption. Results show that depression and anxiety symptoms significantly increased over the three years, and these changes were moderated by changes in alcohol consumption and binge drinking. Students with increased depression symptoms were less likely to reduce their alcohol consumption in the early pandemic (Adjust odds ratio [AOR] 0.94, 95% CI:0.90-0.98), more likely to initiate alcohol consumption in the ongoing pandemic period (AOR 1.03, 95% CI: 1.01-1.05), and more likely to initiate binge drinking in both periods. The depression-alcohol use association was stronger among females than males. This study demonstrates a modest association between internalizing symptoms and alcohol use, particularly for depression symptoms and in females. The identified depression-alcohol use association suggests that preventing or treating depression might be beneficial for adolescent alcohol use and vice versa.

Physical activity and recreational screen time change among adolescents in Canada: Examining the impact of COVID-19 in worsening inequity.

The purpose of this study was to assess if sub-populations of adolescents in Canada (i.e., race/ethnicity, sex/gender, and socioeconomic status [SES]) experienced a larger change in physical activity and screen time between the 2019-2020 (pre-pandemic) and the 2020-2021 (mid-pandemic) school years. Longitudinally linked data from pre-pandemic and mid-pandemic school years of a prospective cohort study of secondary school students in Canada (n = 8209) were used for these analyses. Multivariable regression modelling tested the main effects of race/ethnicity, sex/gender, and SES on changes in moderate-to-vigorous physical activity (MVPA) and screen time duration as well as adherence to Canada's 24-h Movement Guidelines. Overall between groups difference were assessed using type II analysis of deviance tests. Interactions between variables of interest were subsequently tested with a series of regression models compared to the main effects model using likelihood-ratio test. Post-hoc comparisons found Male participants' MVPA time decreased less compared to their female counterparts (M [95% CI] = -16.3 [-13.5, -19.2] min/day), but also reported greater increases in screen time compared to females (23.7 [14.7, 32.8] min/day) during the same period. MVPA in White participants decreased less than Asian participants (-10.7 [-19.5, -1.9] min/day) with a similar non-significant pattern observed in Black and Latin participants. Adolescents in higher SES categories fared better on adherence to MVPA (highest vs. lowest OR = 1.41 [0.97, 2.06]) and screen time recommendations(highest vs. lowest AOR = 3.13 [0.91, 11.11]). Results support the hypothesis that existing inequitable sociodemographic differences in MVPA participation and screen time have worsened throughout the pandemic.

Youth Vaping During the Early Stages of the COVID-19 Pandemic Period: Adjusted Annual Changes in Vaping Between the Pre-COVID and Initial COVID-Lockdown Waves of the COMPASS Study.

BACKGROUND: Adolescence is a critical period for vaping onset. The purpose of this article was to examine the effect of the early stages of the COVID-19 pandemic period on youth vaping. METHODS: We used 3-year linked data from the COMPASS study, including 7585 Canadian (Quebec, Ontario) adolescents from which 1949 completed all three survey waves (pre-COVID-19 [2018, 2019] and online [2020] during the early pandemic period [May-July 2020]) and provided vaping data. Structural equation modeling (SEM) and difference-in-difference (DD) models were used to estimate pre-COVID-19 to initial COVID-19 pandemic period change (2019-2020) in vaping (monthly, weekly, daily) compared with 2018-2019 change to adjust for age-related effects. Models were adjusted for age of entry into the cohort and sociodemographic characteristics. RESULTS: In the SEM and DD models, the proportion of youth who were monthly and weekly vaping increased from 2018 to 2019 but decreased from 2019 to 2020; daily vaping increased across all waves. However, for all vaping outcomes modeled, the expected increases from the pre-COVID-19 wave (2019) to the initial COVID-19 period wave (2020) were lesser relative to the changes seen across the 2018 to 2019 waves. CONCLUSION: The early stages of the COVID-19 pandemic period appear to be associated with a reduction in the proportion of youth who were monthly and weekly vapers in our adjusted longitudinal models. While daily vaping increased over this same period of time, the magnitude of the increase in our adjusted longitudinal models appears attenuated by the early stages of the pandemic. IMPLICATIONS: This large prospective study of youth that included pre-pandemic data is unique in that we were able to identify that the early stages of the COVID-19 pandemic period was associated with a reduction in the proportion of youth who were monthly and weekly vapers in our adjusted longitudinal models. Conversely, the proportion of youth who were daily vaping increased over this same period of time, but the magnitude of the increase appears smaller than expected during the early stages of the pandemic in our adjusted longitudinal models. This study provides novel robust evidence that the patterns of vaping most aligned with onset and progression (i.e., monthly and weekly use) appear attenuated during the initial pandemic period.

Stronger together: Coping behaviours and mental health changes of Canadian adolescents in early phases of the COVID-19 pandemic.

BACKGROUND: The impact of the COVID-19 pandemic and consequent public health restrictions on the mental health of adolescents is of global concern. The purpose of this study was to examine how Canadian adolescents coped during the early pandemic and whether different coping methods were associated with changes in mental health from before the pandemic to the early lockdown response. METHODS: Using two-year linked survey data (2018-2020) from a prospective cohort of secondary school students (n = 3,577), linear regression models were used to examine whether changes in mental health (anxiety [Generalized Anxiety Disorder-7 scale], depression [Center for Epidemiologic Studies Depression 10-item scale Revised], emotion regulation [Difficulties in Emotion Regulation Scale], psychosocial well-being [Flourishing scale]) were related to each coping behaviour. RESULTS: The most common reported coping behaviours included staying connected with friends online (78.8%), playing video games, watching TV/movies, and/or surfing the internet/social media (76.2%), studying or working on schoolwork (71.0%), and getting exercise (65.2%). The use of positive coping mechanisms during the early pandemic period (e.g., keeping a regular schedule, time with family, time with friends online) was associated with less adverse mental health changes from before to during the early lockdown; whereas, negative coping mechanisms (e.g., spending time alone, eating junk food) were consistently associated with more adverse mental health changes. CONCLUSION: This study demonstrates the importance of social support and connections with both friends and family, as well as keeping and maintaining a routine, over the pandemic. Interventions supporting positive relationships and engagement in these coping behaviours may be protective for adolescent mental health during disruptive events.

Learning from missing data: examining nonreporting patterns of height, weight, and BMI among Canadian youth.

BACKGROUND: Youth body mass index (BMI), derived from self-reported height and weight, is commonly prone to nonreporting. A considerable proportion of overweight and obesity (OWOB) research relies on such self-report data, however little literature to date has examined this nonreporting and the potential impact on research conclusions. The objective of this study was to examine the characteristics and predictors of missing data in youth BMI, height, and weight. METHODS: Using a sample of 74,501 Canadian secondary school students who participated in the COMPASS study in 2018/19, sex-stratified generalized linear mixed models were run to examine predictors of missing data while controlling for school-level clustering. RESULTS: In this sample, 31% of BMI data were missing. A variety of diet, exercise, mental health, and substance use variables were associated with BMI, height, and weight missingness. Perceptions of being overweight (females: 95% CI (1.42,1.62), males: 95% CI (1.71,2.00)) as well as intentions to lose weight (females: 95% CI (1.17,1.33), males: 95% CI (1.13,1.32)) were positively associated with BMI missingness. CONCLUSIONS: Findings from this study suggest that nonreporting in youth height and weight is likely somewhat related to the values themselves, and hint that social desirability may play a substantial role in nonreporting. The predictors of missingness identified in this study can be used to inform future studies on the potential bias stemming from missing data and identify auxiliary variables that may be used for multiple imputation approaches.

A scoping review of school-level risk and protective factors of youth cannabis use: An application of the socio-ecological model.

Risk and protective factors for cannabis use exist at various levels of influence, and the school environment can play a key role in preventing cannabis use and initiation as most youth. By using the socio-ecological model to hierarchically characterize school-specific risk and protective factors, a wholistic approach to school-based cannabis use prevention can be demonstrated. This study uses scoping review methodology to describe current research on school-level risk and protective factors of youth cannabis use. The socio-ecological model was used as a guiding framework to characterize the literature. PubMed, Embase, and Scopus were used to retrieve original research articles published between 2010 and 2020 that examined cannabis use as a main outcome of interest. Articles that examined school-related risk and protective factors within participants who were 18 years old or younger were included. Articles that met the pre-established criteria were extracted and categorised by theme based on levels of the socio-ecological framework. Four levels of risk and protective factors related to the school environment were identified (individual, interpersonal, community, and societal). A majority of school-based research examined individual and societal factors that influenced youth cannabis use. Our findings suggest most available research has focused on individual and societal school-level factors of cannabis use. A number of consistent themes were identified, however, findings were mixed and demonstrate the need for a more critical examination of research in order to understand which risk and protective factors are most influential among youth.

More support needed: Evaluating the impact of school e-cigarette prevention and cessation programs on e-cigarette initiation among a sample of Canadian secondary school students.

Given the recent increase in e-cigarette use among adolescents, there is a need to further explore how school programs are associated with e-cigarette initiation. The objective of this quasi-experimental study was to evaluate the impact of multiple school-based e-cigarette prevention and cessation programs on e-cigarette initiation among Canadian adolescents. This study used data from Year 6 (2017/18) and Year 7 (2018/19) of the COMPASS study in British Columbia, Alberta, Ontario, and Quebec, Canada. Students in grades 9 to 11 who had never tried e-cigarettes at baseline were included (n = 13,269). Schools (n = 88) reported whether they added programming that addressed e-cigarette or tobacco prevention or cessation. Generalized estimating equations were used to identify how added programs were associated with e-cigarette initiation at follow-up. At one-year follow-up (2018/19), 23% of schools added programs. Our evaluation results suggest that none of the activities taken by schools to prevent or reduce vaping among students significantly prevented vaping onset. In fact, female students at schools that reported adding a theme week had higher odds of e-cigarette initiation (OR 1.68 [95% CI 1.31-2.16]) and male students at schools that reported a cessation program had higher odds of e-cigarette initiation (OR 1.20 [95% CI 1.01-1.44]). These results suggest that schools may not know how to address e-cigarette use and that there can be risks to students if programs are not carefully implemented. Results point to the need for additional support to ensure that schools are taking evidence-based approaches that support all students.

Disparities in high schools' vaccination coverage (COVID-19). A natural experiment in the Province of Quebec.

Teenagers' vaccination has become crucial to limit the COVID-19 transmission in the population. To increase the vaccination rate of this age group, a school-based vaccination campaign was launched in Québec, Canada from June 7 to 18, 2021. This study aimed to analyze trajectories of vaccination coverage over time among students attending 37 high schools. The study explored whether school-based vaccination campaigns contributed to the progression of the vaccination coverage and attenuated disparities in vaccination coverage across schools. On average, first dose coverage quickly increased from 30.6% to 81.5% between June 6 and 18, 2021, after the launch of the campaign. As of August 13, 2021, first dose coverage had reached 87.9% and 64.9% for the second dose coverage. Public schools with poorer student populations had 6.5 points of percentage lower first dose vaccination rates (95%CI 0.3%; 12.6%) compared to other schools. A higher level of concern related to the pandemic among students was associated with a 4.3 points of percentage increased coverage (95%CI 0.7%; 8.0%). The initial uneven distribution in first dose coverage decreased dramatically by the end of the campaign. Similar trends were observed for the second dose, although between schools' inequality at the end of the period of observation was significantly larger. The school-based vaccination campaign might have initially contributed to a prompt rise in vaccination coverage and helped the disadvantaged schools to reach similar vaccination coverage as seen in other schools. In addition to being an efficient way to achieve rapidly high vaccination coverage, the school-based approach might contribute to increase equity in vaccination distribution.

Longitudinal Associations Between e-Cigarette Use, Cigarette Smoking, Physical Activity, and Recreational Screen Time in Canadian Adolescents.

INTRODUCTION: This study examined longitudinal associations between e-cigarette use, cigarette smoking, physical activity, and recreational screen time (ST) in a cohort of Canadian adolescents (ages 14-17 years; grades 9-12). AIMS AND METHODS: Data from 5951 adolescents who participated in COMPASS Year 4 (2015-2016; baseline) and Year 6 (2017-2018; follow-up) were used. Exposures included e-cigarette use and cigarette smoking. Outcomes included cutpoints for moderate- to vigorous-physical activity (MVPA; ≥60 min/d), muscular strengthening exercises (MSE; ≥3 time/wk), participation in sport (SP; intramural or competitive), and recreational screen time (ST; ≤430 min/day). Generalized linear mixed models were performed. RESULTS: e-Cigarette use (16.6% vs. 39.2%), cigarette smoking (0.9% vs. 4.7%), and dual use (0.8% vs. 4.1%) increased from baseline to follow-up. SP (70.8% vs. 61.3%) and the prevalence of meeting MVPA (49.8% vs. 42.1%) and MSE cutpoints (54.0% vs. 45.3%) decreased from baseline to follow-up. Recreational ST remained similar from baseline to follow-up. New e-cigarette use at follow-up was associated with maintenance of SP and meeting MVPA and MSE cutpoints, but also with increased ST. New cigarette smoking at follow-up was associated with maintaining high ST and low SP. Cigarette smoking at baseline and follow-up was associated with maintaining high ST, low MSE, and low SP. Cigarette smoking cessation at follow-up was associated with increasing MVPA and MSE, decreasing ST, and maintaining low SP. CONCLUSION: Given the clustering and co-occurring unhealthy behavioral patterns, intervention strategies to promote healthy lifestyles should take a holistic approach, by targeting multiple behavioral changes simultaneously. IMPLICATIONS: This investigation highlighted that, unhealthy behaviors, particularly e-cigarette use, cigarette smoking, and excessive use of screens, tend to co-occur among Canadian adolescents. Therefore, intervention strategies to promote healthy lifestyles should take a holistic approach, by targeting multiple behavioral changes simultaneously particularly in school and community settings. As an exception, new and stable e-cigarette use appears to co-occur with achieving sufficient levels of physical activity. Increasing awareness about the risk of e-cigarette use may target population groups that are physically and socially active (eg, athletes, sport teams).

Measurement Invariance of the GAD-7 and CESD-R-10 Among Adolescents in Canada.

OBJECTIVE: The primary objective of our study was to assess measurement invariance (by grade and sex) of the 7-item Generalized Anxiety Disorder (GAD-7) and 10-item Center for Epidemiologic Studies Depression Revised (CESD-R-10) scales in a sample of adolescents in Canada. If measurement invariance was demonstrated, our secondary objective was to estimate differences in scale scores across these subgroups. METHODS: We used data from 59,052 adolescents in Year 7 (2018-19) of the COMPASS school-based study. Measurement invariance was tested within a multigroup confirmatory factor analysis framework. Differences in scale scores were estimated using mixed linear regression which accounted for school-level clustering and adjusted for relevant confounders. RESULTS: Both the GAD-7 and CESD-R-10 demonstrated strict measurement invariance by sex and grade in our sample. Mean scale scores were higher among adolescents in grade 12 compared to grade 9 (ßGAD-7 = 0.91, p < .001; ßCESD-R-10 = 0.99, p < .001) and among female adolescents compared to males (ßGAD-7 = 3.36, p < .001; ßCESD-R-10 = 2.58, p < .001). CONCLUSIONS: Findings support the validity of the GAD-7 and CESD-R-10 for screening risk of generalized anxiety and depression among Canadian adolescents, and further indicate that differences observed in scale scores across subgroups reflect actual differences in risk for generalized anxiety and major depression, respectively.

Understanding Sexual Health Indicators During Adolescence: A Study to Consider Time Since Sexual Debut When Exploring Multiple Sexual Partners.

Understanding risky sexual behaviors among adolescents is key in efforts devoted to reducing the health burden related to sexually transmitted infections and unintended or unplanned pregnancies. The aims of this study were to understand the association between number of lifetime sexual partners and time since sexual debut (TSSD) among adolescents and to determine whether sex modified this association. Data were drawn from the 2018-2019 COMPASS-Quebec study, a cohort study conducted in secondary schools in the province of Quebec, Canada. Of 18,467 respondents aged 14 years and older, 6991 (37.9%; mean age 15.3) reported consensual sexual intercourse and answered questions on their age at sexual initiation and number of lifetime sexual partners. Multilevel Poisson regressions with robust standard errors were estimated to adjust for covariates and produce adjusted group mean differences. The adjusted mean number of lifetime sexual partners ranged from 1.5 for those who had recently begun sexual activity (< 12 months) to 4.0 for those who had been active for > 35 months, an average rise of about 0.6 per year. Females-to-males adjusted mean differences showed that males reported more sexual partners than females at all time points, but the differences were only significant at the shorter (< 12 months) and longer (> 35 months) time spans. This study highlights the importance of taking into account TSSD when using and interpreting the number of lifetime sexual partners as risky sexual behavior among adolescents. Sex did not have a significant modifying effect on the relationship between number of lifetime sexual partners and TSSD.