Simulation modeling of policies directed at youth sugar-sweetened beverage consumption

Impacts of a sugar sweetened beverage tax on body mass index and obesity in Thailand: A modelling study

BACKGROUND

The World Health Organization (WHO) recommends sugar-sweetened beverage (SSB) taxes to address obesity. Thailand has just launched the new tax rates for SSB in 2017; however, the existing tax rate is not as high as the 20% recommended by the WHO. The objective for this study was to estimate the impacts of an SSB tax on body mass index (BMI) and obesity prevalence in Thailand under three different scenarios based on existing SSB and recommended tax rates.

METHODS

A base model was built to estimate the impacts of an SSB tax on SSB consumption, energy intake, BMI, and obesity prevalence. Literature review was conducted to estimate pass on rate, price elasticity, energy compensation, and energy balance to weight change. Different tax rates (11%, 20% and 25%) were used in the model. The model assumed no substitution effects, model values were based on international data since there was no empirical Thai data available. Differential effects by income groups were not estimated.

FINDINGS

When applying 11%, 20%, and 25% tax rates together with 100% pass on rate and an -1.30 own-price elasticity, the SSB consumption decreased by 14%, 26%, and 32%, respectively. The 20% and 25% price increase in SSB price tended to reduce higher energy intake, weight status and BMI, when compared with an 11% increase in existing price increase of SSB. The percentage changes of obesity prevalence of 11%, 20% and 25% SSB tax rates were estimated to be 1.73%, 3.83%, and 4.91%, respectively.

CONCLUSIONS

A higher SSB tax (20% and 25%) was estimated to reduce consumption and consequently decrease obesity prevalence. Since Thailand has already endorsed the excise tax structure, the new excise tax structure for SSB should be scaled up to a 20% or 25% tax rate if the SSB consumption change does not meet a favourable goal.

Impact of competitive foods in public schools on child nutrition: effects on adolescent obesity in the United States an integrative systematic literature review

Background: The United States (US) is currently facing a public health crisis due to the percentage of obesity in adolescents. The Center for Disease Control (CDC) stated the risks for children due to obesity are many. Adolescents obtain a large portion of their daily caloric intake at school; therefore, what foods/drinks they are consuming is so serious.

Objective: To identify and analyze literature on the effects of competitive foods in public schools on adolescent weight, or Body Mass Index (BMI), and possible impacts they may have on adolescent obesity in the United States.

Methods: An integrative systematic review of literature was conducted. The literature was collected in CINAHL, MEDLINE and EMBASE databases. Refined keyword search is further detailed in the report. Year restrictions were 2006–2017 from peer-reviewed journals and published in English, including adolescents 13–18 years old in the US. Criteria for inclusion targeted at least one of (1) sugar-sweetened beverages (SSB), (2) competitive foods, (3) commercial foods, (4) vending machines, (5) al a carte venues, and (6) school stores, examining their associations with weight measurements, using either weight or BMI, or caloric intake analysis.

Results: A total of 164 articles were detected and assessed, for a final analysis of 34 full text articles. Twenty-six articles met the inclusion criteria. Common aspects of interest involved BMI/Obesity/Weight (73%), (58%) examined Calorie density or consumption, (77%) discussed the Availability of competitive foods in schools, (54%) included Analysis of competitive food, beverage and nutrition policies, and (69%) addressed Other effects.

Conclusion: This review discovered substantial evidence that competitive foods are highly available in schools, however, lacking in robust evidence proving causality in increasing BMI or weight. There is strong corroboration in the research revealing that Other effects are factors worthy of studying further. Additional longitudinal and higher-quality research needs to be performed.

Systems Thinking and Simulation Modeling to Inform Childhood Obesity Policy and Practice

OBJECTIVES

In 2007, 31.7% of Georgia adolescents in grades 9-12 were overweight or obese. Understanding the impact of policies and interventions on obesity prevalence among young people can help determine statewide public health and policy strategies. This article describes a systems model, originally launched in 2008 and updated in 2014, that simulates the impact of policy interventions on the prevalence of childhood obesity in Georgia through 2034.

METHODS

In 2008, using information from peer-reviewed reports and quantitative estimates by experts in childhood obesity, physical activity, nutrition, and health economics and policy, a group of legislators, legislative staff members, and experts trained in systems thinking and system dynamics modeling constructed a model simulating the impact of policy interventions on the prevalence of childhood obesity in Georgia through 2034. Use of the 2008 model contributed to passage of a bill requiring annual fitness testing of schoolchildren and stricter enforcement of physical education requirements. We updated the model in 2014.

RESULTS

With no policy change, the updated model projects that the prevalence of obesity among children and adolescents aged ≤18 in Georgia would hold at 18% from 2014 through 2034. Mandating daily school physical education (which would reduce prevalence to 12%) and integrating moderate to vigorous physical activity into elementary classrooms (which would reduce prevalence to 10%) would have the largest projected impact. Enacting all policies simultaneously would lower the prevalence of childhood obesity from 18% to 3%.

CONCLUSIONS

Systems thinking, especially with simulation models, facilitates understanding of complex health policy problems. Using a simulation model to educate legislators, educators, and health experts about the policies that have the greatest short- and long-term impact should encourage strategic investment in low-cost, high-return policies.

Food consumption pattern and obesity in preschool children in Feira de Santana, Bahia, Brazil

ABSTRACT Objective To evaluate the association between food consumption patterns and obesity in preschool children in Feira de Santana, Bahia, Brazil. Methods Cross-sectional, population-based nested within a live-birth cohort study of 813 children, which has started in 2004 in Feira de Santana, Bahia. The anthropometric status among children under four years of age was evaluated based on their body mass index; obesity/severe obesity was defined as a Z-score >+2. The Food Frequency Questionnaire was used to identify dietary patterns using principal components analysis. The association between obesity and food consumption patterns was assessed using Pearson’s Chi-squared test and logistic regression, adopting p<0.05 to denote statistical significance. Results Obesity was detected in 12.7% of the children investigated. Four food consumption patterns were identified: dietary pattern 1 (milk and other dairy products, vegetables and tubers, cereals, legumes, fruits, and fish); dietary pattern 2 (deep-fried or baked snacks, soft drinks/artificial fruit juices, oils and fats, sweets, and coffee/tea); dietary pattern 3 (encased meats, fast food, ketchup/mayonnaise, and eggs); and, dietary pattern 4 (chicken and red meats). Obesity was statistically associated with high adherence to the dietary pattern 3 (OR=1.92; 95%CI=1.01-3.66). Conclusion The results obtained showed that the high intake of energy-dense foods (dietary pattern 3) was a contributing factor to childhood obesity. These data reinforce the need for public policies and food education programs in health units and schools, aiming to change children’s eating habits, significant predictors of nutritional problems.

Comparing the Nutritional Impact of Dietary Strategies to Reduce Discretionary Choice Intake in the Australian Adult Population: A Simulation Modelling Study

Dietary strategies to reduce discretionary choice intake are commonly utilized in practice, but evidence on their relative efficacy is lacking. The aim was to compare the potential impact on nutritional intake of three strategies to reducing discretionary choices intake in the Australian adult (19-90 years) population. Dietary simulation modelling using data from the National Nutrition and Physical Activity Survey 2011-2012 was conducted (n = 9341; one 24 h dietary recall). Strategies modelled were: moderation (reduce discretionary choices by 50%, with 0%, 25% or 75% energy compensation); substitution (replace 50% of discretionary choices with core choices); reformulation (replace 50% SFA with unsaturated fats, reduce added sugars by 25%, and reduce sodium by 20%). Compared to the base case (observed) intake, modelled intakes in the moderation scenario showed: -17.3% lower energy (sensitivity analyses, 25% energy compensation -14.2%; 75% energy compensation -8.0%), -20.9% lower SFA (-17.4%; -10.5%), -43.3% lower added sugars (-41.1%; -36.7%) and 17.7% lower sodium (-14.3%; -7.5%). Substitution with a range of core items, or with fruits, vegetables and core beverages only, resulted in similar changes in energy intake (-13.5% and -15.4%), SFA (-17.7% and -20.1%), added sugars (-42.6% and -43%) and sodium (-13.7% and -16.5%), respectively. Reformulating discretionary choices had minimal impact on reducing energy intake but reduced SFA (-10.3% to -30.9%), added sugars (-9.3% to -52.9%), and alcohol (-25.0% to -49.9%) and sodium (-3.3% to -13.2%). The substitution and reformulation scenarios minimized negative changes in fiber, protein and micronutrient intakes. While each strategy has strengths and limitations, substitution of discretionary choices with core foods and beverages may optimize the nutritional impact.

Use and cumulation of evidence from modelling studies to inform policy on food taxes and subsidies: biting off more than we can chew?

Background

Food tax-subsidy policies are proposed to hold promise for helping to produce healthier patterns of food purchasing and consumption at population level. Evidence for their effects derives largely from simulation studies that explore the potential effects of untried policies using a mathematical modelling framework. This paper provides a critique first of the nature of the evidence derived from such simulation studies, and second of the challenges of cumulating that evidence to inform public health policy.

Discussion

Effects estimated by simulation studies of food taxes and subsidies can be expected to diverge in potentially important ways from those that would accrue in practice because these models are simplified, typically static, representations of complex adaptive systems. The level of confidence that can be placed in modelled estimates of effects is correspondingly low, and the level of associated uncertainty is high. Moreover, evidence from food tax-subsidy simulation studies cannot meaningfully be cumulated using currently available quantitative evidence synthesis methods, to reduce uncertainty about effects.

Summary

Simulation studies are critical for the initial phases of an incremental research process, for drawing together diverse evidence and exploring potential longer-term effects. While simulation studies of food taxes and subsidies provide a valuable and necessary input to the formulation of public health policy in this area, they are unlikely to be sufficient, and policy makers should not place excessive reliance on evidence from such studies, either singly or cumulatively. To reflect known and unknown limitations of the models, results of such studies should be interpreted cautiously as tentative projections. Modelling studies should increasingly be integrated with more empirical studies of the effects of food tax and subsidy policies in practice.

Evaluating environmental change strategies: challenges and solutions

In this introductory article we define environmental change strategies (ECS), summarize the primary challenges associated with evaluating ECS, and provide an overview of the methods researchers have employed to begin to address these challenges. This special issue provides a range of examples, from researchers and practitioners in the field, of different approaches for addressing these challenges. These articles present new methods to understand and test how ECS are implemented and propose methods to evaluate their implementation. The content of the articles covers multiple public health issues, including substance abuse prevention, tobacco control, HIV prevention, and obesity prevention. This special issue is intended to build the evidence base for effective ECS, generate compelling discussion, critical analyses, and spur future research that will help improve the implementation and evaluation of ECS.