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BACKGROUND: Healthy Together Victoria (HTV) was a Victorian Government initiative that sought to reduce the prevalence of overweight and obesity through targeting chronic disease risk factors including physical activity, poor diet quality, smoking, and harmful alcohol use. The intervention involved a boosted workforce of > 170 local-level staff in 12 communities; employed to deliver system activation around health and wellbeing for individuals, families and communities. A cluster randomised trial (CRT) of a systems thinking approach to obesity prevention was embedded within HTV. We present the two-year changes in overweight and obesity and associated behaviours among secondary school students across Victoria, Australia. METHODS: Twenty-three geographically bounded areas were randomised to intervention (12 communities) or comparison (11 communities). Randomly selected secondary schools within each community were invited to participate in the trial in 2014 and 2016. Students in Grade 8 (aged approximately 13-15 years) and Grade 10 (aged approximately 15-16 years) at participating schools were recruited using an opt-out approach across July-September 2014 and 2016. Primary outcomes were body mass index (BMI) and waist circumference. Secondary outcomes were physical activity, sedentary behaviour, diet quality, health-related quality of life, and depressive symptoms. Linear mixed models were fit to estimate the intervention effect adjusting for child/school characteristics. RESULTS: There were 4242 intervention children and 2999 control children in the final analysis. For boys, the two-year change showed improvement in intervention versus control for waist circumference (difference in change: - 2.5 cm; 95% confidence interval [CI]: - 4.6, - 0.5) and consumption of sugar-sweetened beverages per day (< 1 serve: 8.5 percentage points; 95% CI: 0.6, 16.5). For girls, there were no statistically significant differences between conditions. CONCLUSIONS: HTV seemed to produce favourable changes in waist circumference and sugar-sweetened beverage consumption for boys, however, no effect on BMI was observed. Although the HTV intervention was cut short, and the period between data collection points was relatively short, the changes observed in HTV contribute to the growing evidence of whole-of-community interventions targeting childhood obesity. TRIAL REGISTRATION: This trial is unregistered. The intervention itself was a policy setting delivered by government and our role was the collection of data to evaluate the effect of this natural experiment. That is, this study was not a trial from the classical point of view and we were not responsible for the intervention.
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Obesidade Infantil , Feminino , Humanos , Masculino , Sobrepeso/prevenção & controle , Obesidade Infantil/epidemiologia , Obesidade Infantil/prevenção & controle , Qualidade de Vida , Instituições Acadêmicas , Estudantes , Análise de Sistemas , Vitória/epidemiologia , AdolescenteRESUMO
Frequent potentially avoidable presentations to Emergency Departments (EDs) represent a complex problem, driven by multiple interdependent and interacting factors that change over time and influence one another. We sought to describe and map the drivers of frequent potentially avoidable presentations to a regional ED, servicing regional and rural areas, and identify possible solutions from the perspectives of key stakeholders. This study used a qualitative, community-based systems dynamics approach utilising Group Model Building (GMB). Data were collected from two 3-h online workshops embedded with small-group discussions and conducted with stakeholder groups operating within a regional health system. Stakeholders were guided through a series of participatory tasks to develop a causal loop diagram (CLD) using Systems Thinking in Community Knowledge Exchange software (n=29, workshop one), identify potential action points and generate a prioritised action list to intervene in the system (n=21, workshop two). Data were collected through note taking, real-time system mapping, and recording the workshops. Each action was considered against the Public Health 12 framework describing twelve leverage points to intervene in a system. A CLD illustrating the complex and interrelated factors that drive frequent potentially avoidable ED presentations was developed and classified into four categories: (1) access to services; (2) coordination; (3) patient needs; and (4) knowledge and skills. Nine action areas were identified, with many relating to care and service coordination. Most actions aligned with lower-level system impact actions. This study provides an in-depth understanding of influencing factors and potential solutions for frequent potentially avoidable ED presentations across a regional health system. The CLD demonstrates frequent potentially avoidable ED presentations are a complex problem and identified that a prevention response should engage with system- and individual-level solutions. Further work is needed to prioritise actions to support the implementation of higher-level system impacts.
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BACKGROUND: World-wide, health service providers are moving towards innovative models of clinical home-based care services as a key strategy to improve equity of access and quality of care. To optimise existing and new clinical home-based care programs, evidence informed approaches are needed that consider the complexity of the health care system across different contexts. METHODS: We present a protocol for working with health services and their partners to perform rapid identification, prioritisation, and co-design of content-appropriate strategies to optimise the delivery of healthcare at home for older people in rural and regional areas. The protocol combines Systems Thinking and Implementation Science using a Consensus Mapping and Co-design (CMC) process delivered over five workshops. DISCUSSION: The protocol will be implemented with rural and regional healthcare providers to identify digital and non-digital solutions that have the potential to inform models of service delivery, improve patient experience, and optimise health outcomes. The combination of system and implementation science is a unique approach for optimising healthcare at home for older populations, especially in the rural context where need is high. This is the first protocol to integrate the use of systems and implementation science into one process and articulating these methods will help with replicating this in future practice. Results of the design phase will translate into practice through standard health service planning methods to enhance implementation and sustainability. The delivery of the protocol will include building capacity of health service workers to embed the design, implementation, and evaluation approach into normal practice. This protocol forms part of the DELIVER (Delivering Enhanced heaLthcare at home through optImising Virtual tools for oldEr people in Rural and regional Australia) Project. Funded by Australia's Medical Research Future Fund, DELIVER involves a collaboration with public health services of Western Victoria, Australia.
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Pesquisa Biomédica , Instalações de Saúde , Humanos , Idoso , Vitória , Consenso , Mão de Obra em SaúdeRESUMO
Developing safety interventions using patient feedback is valuable for creating safer systems of health care. A qualitative process evaluation of a patient feedback on safety intervention was undertaken in six primary care practices. The purpose was to theorize factors mediating with the implementation of the intervention using existing theories. The intervention required practices to obtain patient feedback on safety using a validated tool and respond using quality improvement methods. Multiple methods of qualitative data collection were used, including interviews and overt observation. Abductive reasoning informed the iterative process of analysis that examined theories relevant to the intervention and setting. A theoretical framework was developed, which encompassed mediating factors grouped under three concepts: practice readiness, utilization of problem-solving skills, and agency. Theorizing mediating factors was necessary to understand the complexities of primary care practices, and to identify the essential components for implementation of the intervention on a larger scale.
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Atenção Primária à Saúde , Melhoria de Qualidade , Atenção à Saúde , Retroalimentação , Humanos , Segurança do PacienteRESUMO
Background: Research has highlighted the multitude of factors that are negatively associated with coach mental well-being but has failed to investigate how the determinants of mental well-being can affect the coach both positively and negatively. Accordingly, the aim of this study was to investigate levels of mental well-being among sport coaches and assess whether areas of work life-specifically workload and control-are related to levels of mental well-being. Method: An online survey comprising demographic and coaching experience details, the Areas of Work Life Scale (AWS), and the Warwick-Edinburgh Mental Well-Being Scale was completed by 464 Australian coaches involved in a range of sports. Differences in coach mental well-being according to key demographic and coaching-related subgroups were assessed using separate t-test and ANOVA analyses and the magnitude of effects was determined using Cohen's d and the eta-squared (ή2) statistics. Multiple linear regression was used to examine relationships between both workload and control and mental well-being after controlling for age, gender, coaching setting and weekly coaching activity. Results: The findings indicate poorer mental well-being among both male and younger coaches and indicate that coach mental well-being is related to the ability to self-manage the workload associated with their role as a coach as well as greater autonomy over coaching-related tasks and activities. Specifically, a one-unit increase in AWS workload and AWS control were associated with ~three- and ~four-unit increases in coach mental well-being, respectively. Conclusion: Greater provision of resources and education is required to assist coaches to manage their own mental well-being, while being supported by the organisation they coach for. Enabling coaches to balance their coaching requirements and to have control over their environment will improve their ability to constantly coach at a high standard.
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Nível de Saúde , Saúde Mental/estatística & dados numéricos , Tutoria , Esportes/psicologia , Adulto , Austrália/epidemiologia , Feminino , Indicadores Básicos de Saúde , Inquéritos Epidemiológicos , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Ocupacional/epidemiologia , Estresse Ocupacional/etiologia , Estresse Ocupacional/psicologia , Autonomia Profissional , Carga de Trabalho/psicologiaRESUMO
BACKGROUND: Cardiovascular diseases (CVD) are the largest cause of death and disability in Australia. Australian national guidelines for the primary prevention of CVD recommend that all adults without CVD and aged 45 years or more are screened for their absolute risk of CVD every 2 years. Despite the compelling evidence to address CVD risk, treatment gaps remain and evidence suggests that much of the shortcomings are attributed to the performance of primary care practices. To address this issue, a quality improvement initiative is being implemented in a large urban multidisciplinary primary care practice in the South West region of Victoria, Australia. The key outcome of this intervention will be to increase the use and acceptability of CVD risk assessment guidelines. To ensure the intervention is tracking toward its objectives, a robust monitoring and evaluation framework was established. METHOD/DESIGN: A novel framework that assimilates key traditional and theory-driven evaluation practices was developed to assess the impact of the intervention. The framework approach is termed the integrated model of evaluation (IMoE). Researchers and stakeholders convened several times to discuss and develop the evaluation protocol and align it with the quality intervention. The main objective here is to explore the feasibility of an integrated approach to evaluating clinical quality improvement interventions. The sub-objectives are to test the alignment of the IMoE to clinical quality improvement projects and its ability to derive findings to the satisfaction of stakeholders. The design and establishment of the evaluation approach is discussed in further detail in this article. DISCUSSION: The novel feature of the IMoE is its emphasis on tracking 'change' in practices that lead to quality improvement. This emphasis suits the quality improvement theme of this initiative as identification of change elements and explanation behind change is necessary to sustain and promote quality improvement. The other principle behind development of this model, which emphasises practicality in implementation, is to ensure stakeholders gain greatest value from the commissioning of program evaluation. By incorporating practical components and leaving out esoteric concepts, this approach ensures evaluation can be undertaken in realistic timeframes. ETHICS APPROVAL: The quality improvement intervention and evaluation framework received approval from the Deakin University Human Research Ethics Committee (Approval Number: 2017-313).
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OBJECTIVE: The Australian Capital Territory 'It's Your Move!' (ACT-IYM) was a three-year (2012-2014) systems intervention to prevent obesity among adolescents. METHODS: The ACT-IYM project involved three intervention schools and three comparison schools and targeted secondary students aged 12-16 years. The intervention consisted of multiple initiatives at individual, community, and school policy level to support healthier nutrition and physical activity. Intervention school-specific objectives related to increasing active transport, increasing time spent physically active at school, and supporting mental wellbeing. Data were collected in 2012 and 2014 from 656 students. Anthropometric data were objectively measured and behavioural data self-reported. RESULTS: Proportions of overweight or obesity were similar over time within the intervention (24.5% baseline and 22.8% follow-up) and comparison groups (31.8% baseline and 30.6% follow-up). Within schools, two of three the intervention schools showed a significant decrease in the prevalence of overweight and obesity (p<0.05). CONCLUSIONS: There was some evidence of effectiveness of the systems approach to preventing obesity among adolescents. Implications for public health: The incorporation of systems thinking has been touted as the next stage in obesity prevention and public health more broadly. These findings demonstrate that the use of systems methods can be effective on a small scale.
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Exercício Físico , Comportamentos Relacionados com a Saúde , Promoção da Saúde/organização & administração , Obesidade/prevenção & controle , Serviços de Saúde Escolar/organização & administração , Adolescente , Austrália/epidemiologia , Território da Capital Australiana/epidemiologia , Criança , Comportamento Alimentar , Feminino , Promoção da Saúde/métodos , Humanos , Masculino , Obesidade/epidemiologia , Sobrepeso/epidemiologia , Sobrepeso/prevenção & controle , Prevalência , Instituições Acadêmicas , EstudantesRESUMO
BACKGROUND: The after-school period has been described as the 'critical window' for physical activity (PA) participation. However, little is known about the importance of this window compared with the before and during-school period among socioeconomically disadvantaged children, and influence of gender and weight status. METHODS: 39 out of 156 (RR=25%) invited primary schools across 26 local government areas in Victoria, Australia, consented to participate with 856 children (RR=36%) participating in the wider study. The analysis sample included 298 Grade 4 and Grade 6 children (mean age: 11.2±1.1; 44% male) whom met minimum accelerometry wear-time criteria and had complete height, weight and health-behaviours questionnaire data. Accelerometry measured duration in daily light-intensity PA (LPA), moderate-to-vigorous PA (MVPA) and sedentary time (ST) was calculated for before-school=8-8:59, during-school=9:00-15:29 and after-school=15:30-18:00. Bivariate and multivariable linear regression analyses were conducted. RESULTS: During-school represented the greatest accumulation of LPA and MVPA compared with the before and after-school periods. Boys engaged in 102â min/day of LPA (95% CI 98.5 to 104.9) and 62â min/day of MVPA (95% CI 58.9 to 64.7) during-school; girls engaged in 103â min/day of LPA (95% CI 99.7 to 106.5) and 45â min/day of MVPA (95% CI 42.9 to 47.4). Linear regression models indicated that girls with overweight or obesity engaged in significantly less LPA, MVPA and more time in ST during-school. CONCLUSIONS: This study highlights the importance of in-school PA compared with after-school PA among socioeconomically disadvantage children whom may have fewer resources to participate in after-school PA.
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Peso Corporal , Exercício Físico , Comportamentos Relacionados com a Saúde , Comportamento Sedentário , Populações Vulneráveis/estatística & dados numéricos , Acelerometria , Criança , Estudos Transversais , Feminino , Humanos , Modelos Lineares , Masculino , Sobrepeso/epidemiologia , Obesidade Infantil/epidemiologia , Instituições Acadêmicas , Autorrelato , Fatores Sexuais , Fatores de Tempo , Vitória/epidemiologiaRESUMO
BACKGROUND: Healthy Together Victoria (HTV) - a complex 'whole of system' intervention, including an embedded cluster randomized control trial, to reduce chronic disease by addressing risk factors (physical inactivity, poor diet quality, smoking and harmful alcohol use) among children and adults in selected communities in Victoria, Australia (Healthy Together Communities). OBJECTIVES: To describe the methodology for: 1) assessing changes in the prevalence of measured childhood obesity and associated risks between primary and secondary school students in HTV communities, compared with comparison communities; and 2) assessing community-level system changes that influence childhood obesity in HTC and comparison communities. METHODS: Twenty-four geographically bounded areas were randomized to either prevention or comparison (2012). A repeat cross-sectional study utilising opt-out consent will collect objectively measured height, weight, waist and self-reported behavioral data among primary [Grade 4 (aged 9-10y) and Grade 6 (aged 11-12y)] and secondary [Grade 8 (aged 13-14y) and Grade 10 (aged 15-16y)] school students (2014 to 2018). Relationships between measured childhood obesity and system causes, as defined in the Foresight obesity systems map, will be assessed using a range of routine and customised data. CONCLUSION: This research methodology describes the beginnings of a state-wide childhood obesity monitoring system that can evolve to regularly inform progress on reducing obesity, and situate these changes in the context of broader community-level system change.
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OBJECTIVES: Adolescence is a period of increased risk for mental health problems and development of associated lifestyle risk behaviours. This study examined cross-sectional and longitudinal associations between obesogenic risk factors, weight status, and depressive symptomatology in a cohort of Australian adolescents. DESIGN: Prospective cohort study. SETTING: The study used repeated measures data from the Australian Capital Territory (ACT) It's Your Move project, an Australian community-based obesity prevention intervention. Intervention effect was non-significant therefore intervention and comparison groups were combined in this study. PARTICIPANTS: Total sample was 634 secondary school students (female n=338, male n=296) with mean age 13 years (SD=0.6) at baseline (2012) and 15 years (SD=0.6) at follow-up (2014) recruited from 6 government secondary schools in the ACT. PRIMARY AND SECONDARY OUTCOMES MEASURES: Primary outcome was depressive symptomatology measured by Short Mood and Feelings Questionnaire. Secondary outcomes were weight status, physical activity, screen time and diet related measures. RESULTS: Increased physical activity was associated to lower depressive symptomatology among males (OR=0.35, p<0.05). Sweet drink (OR=1.15, p<0.05) and takeaway consumption (OR=1.84, p<0.05) were associated with higher levels of depressive symptomatology among females at follow-up. Males who were classified as overweight or obese at baseline, and remained so over the study period, were at increased risk of depressive symptomatology at follow-up (b=1.63, 95% CI 0.33 to 2.92). Inactivity among males over the 2-year study period was predictive of higher depressive symptomatology scores at follow-up (b=2.55, 95% CI 0.78 to 4.32). For females, those who increased their consumption of takeaway foods during the study period were at increased risk for developing depressive symptomatology (b=1.82, 95% CI -0.05 to 3.71). CONCLUSIONS: There are multiple, probably complex, relationships between diet, physical activity and outcomes of obesity and mental health as well as between the outcomes themselves. Healthier diets and increased physical activity should be foundations for healthier body weight and mental health. TRIAL REGISTRATION NUMBER: ACTRN12615000842561; Results.
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Comportamento do Adolescente/psicologia , Depressão/diagnóstico , Exercício Físico/psicologia , Comportamento Alimentar/psicologia , Obesidade Infantil/psicologia , Adolescente , Austrália/epidemiologia , Peso Corporal , Estudos Transversais , Depressão/epidemiologia , Dieta , Feminino , Seguimentos , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Estilo de Vida , Masculino , Obesidade Infantil/epidemiologia , Estudos Prospectivos , Fatores de Risco , Assunção de Riscos , Inquéritos e QuestionáriosRESUMO
BACKGROUND: Insufficient sleep is potentially an important modifiable risk factor for obesity and poor physical activity and sedentary behaviours among children. However, inconsistencies across studies highlight the need for more objective measures. This paper examines the relationship between sleep duration and objectively measured physical activity, sedentary time and weight status, among a sample of Victorian Primary School children. METHODS: A sub-sample of 298 grades four (n = 157) and six (n = 132) Victorian primary school children (aged 9.2-13.2 years) with complete accelerometry and anthropometry data, from 39 schools, were taken from a pilot study of a larger state based cluster randomized control trial in 2013. Data comprised: researcher measured height and weight; accelerometry derived physical activity and sedentary time; and self-reported sleep duration and hypothesised confounding factors (e.g. age, gender and environmental factors). RESULTS: Compared with sufficient sleepers (67 %), those with insufficient sleep (<10 hrs/day) were significantly more likely to be overweight (OR 1.97, 95 % CI:1.11-3.48) or obese (OR 2.43, 95 % CI:1.26-4.71). No association between sleep and objectively measured physical activity levels or sedentary time was found. CONCLUSION: The strong positive relationship between weight status and sleep deprivation merits further research though PA and sedentary time do not seem to be involved in the relationship. Strategies to improve sleep duration may help obesity prevention initiatives in the future.
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Obesidade Infantil/epidemiologia , Privação do Sono/epidemiologia , Sono , Estudantes/estatística & dados numéricos , Acelerometria , Adolescente , Antropometria , Criança , Exercício Físico , Feminino , Humanos , Masculino , Sobrepeso/epidemiologia , Projetos Piloto , Risco , Fatores de Risco , Instituições Acadêmicas , Comportamento Sedentário , Autorrelato , Fatores de Tempo , Vitória/epidemiologiaRESUMO
Body mass index and waist circumference are widely used tools to identify risk of non-communicable diseases. Research has indicated that the risk relationships differ by ethnicity. In this study, data from chronic disease surveys in Fiji, Nauru, Solomon Islands and Wallis and Futuna were merged and analysed using receiver operator curves. The action points for body mass index and waist circumference with the highest specificity and sensitivity for identifying the risk of NCDs were identified. The analysis showed considerable differences between Melanesians and other Pacific Islanders, and also gender differences. Action points for non-Melanesians were higher than for Melanesians, and region-wide values are therefore inappropriate.:
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Índice de Massa Corporal , Doenças Cardiovasculares/etiologia , Obesidade/etiologia , Circunferência da Cintura , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Ilhas do Pacífico , Curva ROC , Valores de Referência , Fatores de Risco , Fatores Sexuais , Adulto JovemRESUMO
PURPOSE: To explore the cross-sectional relationships between health-related quality of life (HRQoL) and physical activity (PA) behaviours and screen-based media (SBM) use among a sample of Australian adolescents. METHODS: Data came from baseline measures collected for the It's Your Move! community-based obesity prevention intervention. Questionnaire data on sociodemographics, PA, SBM and HRQoL were collected from 3,040 students (56% boys) aged 11-18 years in grade levels 7-11 in 12 secondary schools. Anthropometric data were measured. RESULTS: The highest level of PA at recess, lunchtime and after school was associated with higher HRQoL scores (boys, by 5.3, 8.1, 6.3 points; girls, by 4.2, 6.1, 8.2 points) compared with not being active during these periods. Exceeding 2 h of SBM use each day was associated with significantly lower HRQoL scores (boys, by 3.2 points; girls, by 4.0 points). Adolescents who were physically active and low SBM users on school days had higher HRQoL scores (boys, by 6.6 points; girls, by 7.8 points) compared with those who were not physically active every school day and high SBM users on school days. CONCLUSIONS: Several of the relationships between low PA and high SBM use and HRQoL were comparable to those previously observed between chronic disease conditions and HRQoL, indicating that these behaviours deserve substantial attention.
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Computadores/estatística & dados numéricos , Exercício Físico , Qualidade de Vida , Comportamento Sedentário , Televisão/estatística & dados numéricos , Adolescente , Austrália , Criança , Estudos Transversais , Feminino , Nível de Saúde , Humanos , Masculino , Obesidade , Inquéritos e Questionários , Jogos de Vídeo/estatística & dados numéricosRESUMO
OBJECTIVES: To examine the relationships between physical activity, sedentary behaviour and body mass index (BMI) among a sample of Australian adolescents. METHODS: Anthropometric, demographic and behavioural data were collected from students (n=3040 mean age 14.6, 44% female) from 12 secondary schools in South West Victoria, Australia (response rate=48.6%). The appropriate descriptive, univariate and regression analysis were used to examine the strength of the associations between physical activity, sedentary behaviour and odds of overweight or obese and the effect of interaction between physical activity and sedentary behaviour on odds of overweight and obese. RESULTS: Males were more likely to be active during the school day than females and had higher median hours of screen time per school day. Physical activity during the school day was associated with higher standardized BMI (BMI-z) among males. Higher levels of activity after school were associated with lower BMI-z for males and females. For both males and females the odds of overweight or obese were higher among the least active. An interaction was observed for females whereby the prevalence of overweight and obesity among the most physically active was lowest for the least sedentary and highest for the most sedentary. CONCLUSIONS: The relationships between physical activity, sedentary behaviour and BMI-z were complex. Interventions to reduce BMI through increasing physical activity or decreasing sedentary behaviour need to consider the complex inter-relationships between these variables and moderating factors such as age, sex and socio economic status in their design and interpretation.
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Comportamento do Adolescente/fisiologia , Índice de Massa Corporal , Atividade Motora/fisiologia , Adolescente , Estudos Transversais , Feminino , Humanos , Masculino , Sobrepeso/epidemiologia , Prevalência , Comportamento Sedentário , Vitória/epidemiologiaRESUMO
The purpose of this mixed methods study was to examine the sources of food and dietary patterns of Tongan adolescents (n = 2084) and their perceptions of sociocultural influences. The study incorporated anthropometric measurements, a behavioral survey, and qualitative interviews. More adolescent Tongan females (82.5%) than males (74.3%) reported sourcing morning tea and/or lunch (females 81.9%, males 72.6%) from school canteens or nearby food outlets. More females than males reported consuming obesity-promoting foods such as packaged snack foods (females 38.2%, males 21.3%), chocolates (females 24.7%, males 15.0%), and soft drinks (females 55.3%, males 50.4%). Food purchased for consumption at schools was predominantly energy dense and nutrient poor. Ensuring that students have access to foods of high nutritional quality sourced from school or home, and restricting access to local food outlets that supply unhealthy products would improve the nutrition status of adolescents in Tonga. Furthermore, it is important that obesity prevention interventions are informed by culture-specific influences to optimize uptake of healthy diets.
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Características Culturais , Dieta/estatística & dados numéricos , Comportamento Alimentar/psicologia , Obesidade/prevenção & controle , Percepção Social , Estudantes/psicologia , Adolescente , Antropometria , Criança , Feminino , Humanos , Masculino , Pesquisa Qualitativa , Instituições Acadêmicas , Fatores Sexuais , Meio Social , Inquéritos e Questionários , Tonga , Adulto JovemRESUMO
Originally, leptin was described as a product of adipocytes that acts on the hypothalamus to regulate appetite. However, subsequently, it has been shown that leptin receptors are distributed widely and that leptin has diverse functions, including promotion of hemopoietic and osteoblastic differentiation. It has been recognized for some time that both serum leptin and bone mass are correlated positively to body fat mass and, recently, we have shown a direct positive relationship between serum leptin and bone mass in nonobese women. We now report that leptin inhibits osteoclast generation in cultures of human peripheral blood mononuclear cells (PBMCs) and murine spleen cells incubated on bone in the presence of human macrophage colony-stimulating factor (hM-CSF) and human soluble receptor activator of NF-kappaB ligand (sRANKL). The half-maximal concentration inhibitory of leptin was approximately 20 nM in the presence of sRANKL at 40 ng/ml but decreased to approximately 2 nM when sRANKL was used at 5 ng/ml. The majority of the inhibitory effect occurred in the first week of the 3-week cultures. Inhibition did not occur when the PBMC cultures were washed vigorously to remove nonadherent cells or when purified CD14+ monocytes were used to generate osteoclasts, indicating an indirect or permissive effect via CD14- PBMC. Leptin increased osteoprotegerin (OPG) messenger RNA (mRNA) and protein expression in PBMC but not in CD14+ cells, suggesting that the inhibitory effect may be mediated by the RANKL/RANK/OPG system. Leptin may act locally to increase bone mass and may contribute to linkage of bone formation and resorption.