A Conceptual Primer on the Potential of Adaptive Policies to Reduce Physical Inactivity.

BACKGROUND: Despite the existence of physical activity policies across many countries, insufficient physical activity remains a major global public health problem. Physical inactivity is an emergent feature of complex systems; it results from a wide range of factors at multiple levels that interact to influence behavior. Traditional approaches to public policy often fail within complex systems, largely due to unpredictability in how the system will respond. Adaptive policies, which are designed to allow for uncertainty about future system behavior and to change over time, may offer a promising solution. In this paper, we introduce the concept of adaptive policies and illustrate how this innovative approach to policy making may be beneficial for reducing physical inactivity. DESIGN: Drawing on existing literature and guiding principles for policy making, we provide 3 examples to illustrate how the concept of adaptive policies can be applied to address physical inactivity. DISCUSSION: The examples illustrate how changes to the way policies and interventions are developed, implemented, and evaluated could help to overcome some of the limitations in existing practices. A key challenge will be engaging policymakers to take a broader perspective of the physical activity system, develop policies that are designed to be adaptable across a range of different future scenarios, and embrace uncertainty and long-term adaptability. CONCLUSION: Adaptive policies may support decision makers globally to achieve the widespread and sustained changes necessary to increase population levels of physical activity.

Mapping complex public health problems with causal loop diagrams.

This paper presents causal loop diagrams (CLDs) as tools for studying complex public health problems like health inequality. These problems often involve feedback loops-a characteristic of complex systems not fully integrated into mainstream epidemiology. CLDs are conceptual models that visualize connections between system variables. They are commonly developed through literature reviews or participatory methods with stakeholder groups. These diagrams often uncover feedback loops among variables across scales (e.g. biological, psychological and social), facilitating cross-disciplinary insights. We illustrate their use through a case example involving the feedback loop between sleep problems and depressive symptoms. We outline a typical step-by-step process for developing CLDs in epidemiology. These steps are defining a specific problem, identifying the key system variables involved, mapping these variables and analysing the CLD to find new insights and possible intervention targets. Throughout this process, we suggest triangulating between diverse sources of evidence, including domain knowledge, scientific literature and empirical data. CLDs can also be evaluated to guide policy changes and future research by revealing knowledge gaps. Finally, CLDs may be iteratively refined as new evidence emerges. We advocate for more widespread use of complex systems tools, like CLDs, in epidemiology to better understand and address complex public health problems.

Estimated changes in free sugar consumption one year after the UK soft drinks industry levy came into force: controlled interrupted time series analysis of the National Diet and Nutrition Survey (2011-2019).

BACKGROUND: The UK soft drinks industry levy (SDIL) was announced in March 2016 and implemented in April 2018, encouraging manufacturers to reduce the sugar content of soft drinks. This is the first study to investigate changes in individual-level consumption of free sugars in relation to the SDIL. METHODS: We used controlled interrupted time series (2011-2019) to explore changes in the consumption of free sugars in the whole diet and from soft drinks alone 11 months after SDIL implementation in a nationally representative sample of adults (>18 years; n=7999) and children (1.5-19 years; n=7656) drawn from the UK National Diet and Nutrition Survey. Estimates were based on differences between observed data and a counterfactual scenario of no SDIL announcement/implementation. Models included protein consumption (control) and accounted for autocorrelation. RESULTS: Accounting for trends prior to the SDIL announcement, there were absolute reductions in the daily consumption of free sugars from the whole diet in children and adults of 4.8 g (95% CI 0.6 to 9.1) and 10.9 g (95% CI 7.8 to 13.9), respectively. Comparable reductions in free sugar consumption from drinks alone were 3.0 g (95% CI 0.1 to 5.8) and 5.2 g (95% CI 4.2 to 6.1). The percentage of total dietary energy from free sugars declined over the study period but was not significantly different from the counterfactual. CONCLUSION: The SDIL led to significant reductions in dietary free sugar consumption in children and adults. Energy from free sugar as a percentage of total energy did not change relative to the counterfactual, which could be due to simultaneous reductions in total energy intake associated with reductions in dietary free sugar.

The impact of the UK soft drink industry levy on the soft drink marketplace, 2017-2020: An interrupted time series analysis with comparator series.

BACKGROUND: In April 2018, the UK government implemented a levy on soft drinks importers and manufacturers, tiered according to the amount of sugar in drinks. The stated aim was to encourage manufacturers to reduce sugar and portion sizes. Previous evidence suggests that the policy has been successful in reducing sugar in drinks in the short-term since implementation, but their sustained effects have not been explored. This study aimed to assess the impact of the soft drink industry levy (SDIL) on sugar levels, price, portion size and use of non-sugar sweeteners in the medium-term. METHODS AND FINDINGS: Product data from 30 November 2017 to 14 March 2020 from one major UK retail supermarket were analysed (112,452 observations, 126 weekly time points). We used interrupted time series analysis, to assess the impact of the soft-drink industry levy (SDIL) on levy-eligible soft drinks, with exempt drinks (i.e. 100% fruit juices, milks, flavoured milks) acting as a comparator series. At the point of implementation of the SDIL (April 2018) there was a step change in the proportion of eligible drinks with sugar content below the SDIL levy threshold (5g per 100ml) (+0.08, 95%CI: +0.04, +0.12), with a similar sized decrease in the proportion in the highest levy category (> = 8g sugar per 100ml) (-0.06, 95%CI: -0.10, -0.03). Between April 2018 and March 2020, the proportion of eligible drinks below the SDIL levy threshold continued to gradually increase (p = 0.003), while those in the highest levy category decreased (p = 0.007). There was a step change in price of eligible drinks in the higher levy category at the point of implementation of +£0.049 (95%CI: +£0.034, +£0.065) per 100mL (for comparison, the levy is set at £0.024 per 100mL for this group). Trends in price for the high levy category were not altered by the SDIL. In the no levy category, there was a step change in price at the implementation (+£0.012 per 100mL, 95%CI: +£0.008, +£0.023), followed by a second step change in October 2018 (-£0.018p per 100mL, 95%CI: -£0.033, -£0.001p). The volume of products in the higher levy group decreased at the time of the implementation (-305mL on average including multipacks, 95%CI: -511, -99). The change in trend for the product volume of drinks in the higher levy group between April 2018 and March 2020 was in the increasing direction (+704mL per year, 95%CI: -95, 1504), but it did not meet our threshold for statistical significance (p = 0.084). There were no changes observed in the volume of lower levy drinks or no levy drinks. There was a step change in the proportion of drinks with non-sugar sweeteners at the implementation of the SDIL (+0.04, 95%CI: +0.02, +0.06). CONCLUSION: These results suggest that the SDIL was successful in [1] producing reductions in sugar levels that were maintained over the medium term up to March 2020 and [2] a reduction in product volume for higher tier drinks that may be diminishing over time. Our results also show that the SDIL was associated with a maintained price differential between high and low sugar drinks.

Systems approaches to scaling up: a systematic review and narrative synthesis of evidence for physical activity and other behavioural non-communicable disease risk factors.

BACKGROUND: Non-communicable diseases (NCDs) are the leading causes of death worldwide. Systems approaches have potential for creating sustainable outcomes at scale but have rarely been used to support scale up in physical activity/nutrition promotion or NCD prevention more generally. This review aimed to: (i) synthesise evidence on the use of systems approaches in scaling up interventions targeting four behavioural risk factors for NCDs; and (ii) to explore how systems approaches have been conceptualised and used in intervention implementation and scale up. METHOD: Seven electronic databases were searched for studies published 2016-2021. Eligible studies targeted at least one of four NCD behavioural risk factors (physical inactivity, tobacco use, alcohol consumption, diet), or described evaluation of an intervention planned for or scaled up. Studies were categorised as having a (i) high, (ii) moderate, or (iii) no use of a systems approach. A narrative synthesis of how systems approaches had been operationalised in scale up, following PRISMA guidelines. RESULTS: Twenty-one intervention studies were included. Only 19% (n = 4) of interventions explicitly used systems thinking to inform intervention design, implementation and scale up (targeting all four risk factors n = 2, diet n = 1, tobacco use n = 1). Five studies ('high use') planned and implemented scale up with an explicit focus on relations between system elements and used system changes to drive impact at scale. Seven studies ('moderate use') considered systems elements impacting scale-up processes or outcomes but did not require achieving system-level changes from the outset. Nine studies ('no use') were designed to work at multiple levels among multiple agencies in an intervention setting, but the complexity of the system and relations between system elements was not articulated. We synthesised reported barriers and facilitators to scaling up, and how studies within each group conceptualised and used systems approaches, and methods, frameworks and principles for scaling up. CONCLUSION: In physical activity research, and NCD prevention more broadly, the use of systems approaches in scale up remains in its infancy. For researchers, practitioners and policymakers wishing to adopt systems approaches to intervention implementation at scale, guidance is needed on how to communicate and operationalise systems approaches in research and in practice. TRIAL REGISTRATION: PROSPERO (CRD42021287265).

Parliamentary reaction to the announcement and implementation of the UK Soft Drinks Industry Levy: applied thematic analysis of 2016-2020 parliamentary debates.

OBJECTIVE: The UK Soft Drinks Industry Levy (SDIL) (announced in March 2016; implemented in April 2018) aims to incentivise reformulation of soft drinks to reduce added sugar levels. The SDIL has been applauded as a policy success, and it has survived calls from parliamentarians for it to be repealed. We aimed to explore parliamentary reaction to the SDIL following its announcement until two years post-implementation in order to understand how health policy can become established and resilient to opposition. DESIGN: Searches of Hansard for parliamentary debate transcripts that discussed the SDIL retrieved 186 transcripts, with 160 included after screening. Five stages of Applied Thematic Analysis were conducted: familiarisation and creation of initial codebooks; independent second coding; codebook finalisation through team consensus; final coding of the dataset to the complete codebook; and theme finalisation through team consensus. SETTING: The United Kingdom Parliament. PARTICIPANTS: N/A. RESULTS: Between the announcement (16/03/2016) - royal assent (26/04/2017), two themes were identified 1: SDIL welcomed cross-party 2: SDIL a good start but not enough. Between royal assent - implementation (5/04/2018), one theme was identified 3: The SDIL worked - what next? The final theme identified from implementation until 16/03/2020 was 4: Moving on from the SDIL. CONCLUSIONS: After the announcement, the SDIL had cross-party support and was recognised to have encouraged reformulation prior to implementation. Lessons for governments indicate that the combination of cross-party support and a policy's documented success in achieving its aim can help cement the resilience of it to opposition and threats of repeal.

Changes in soft drinks purchased by British households associated with the UK soft drinks industry levy: a controlled interrupted time series analysis.

OBJECTIVE: To determine changes in household purchases of drinks 1 year after implementation of the UK soft drinks industry levy (SDIL). DESIGN: Controlled interrupted time series. PARTICIPANTS: Households reporting their purchasing to a market research company (average weekly n=22 091), March 2014 to March 2019. INTERVENTION: A two-tiered tax levied on soft drinks manufacturers, announced in March 2016 and implemented in April 2018. Drinks with ≥8 g sugar/100 mL (high tier) are taxed at £0.24/L, drinks with ≥5 to <8 g sugar/100 mL (low tier) are taxed at £0.18/L. MAIN OUTCOME MEASURES: Absolute and relative differences in the volume of, and amount of sugar in, soft drinks categories, all soft drinks combined, alcohol and confectionery purchased per household per week 1 year after implementation. RESULTS: In March 2019, compared with the counterfactual, purchased volume of high tier drinks decreased by 140.8 mL (95% CI 104.3 to 177.3 mL) per household per week, equivalent to 37.8% (28.0% to 47.6%), and sugar purchased in these drinks decreased by 16.2 g (13.5 to 18.8 g), or 42.6% (35.6% to 49.6%). Purchases of low tier drinks decreased by 170.5 mL (154.5 to 186.5 mL) or 85.8% (77.8% to 93.9%), with an 11.5 g (9.1 to 13.9 g) reduction in sugar in these drinks, equivalent to 87.8% (69.2% to 106.4%). When all soft drinks were combined irrespective of levy tier or eligibility, the volume of drinks purchased increased by 188.8 mL (30.7 to 346.9 mL) per household per week, or 2.6% (0.4% to 4.7%), but sugar decreased by 8.0 g (2.4 to 13.6 g), or 2.7% (0.8% to 4.5%). Purchases of confectionery and alcoholic drinks did not increase. CONCLUSIONS: Compared with trends before the SDIL was announced, 1 year after implementation, volume of all soft drinks purchased combined increased by 189 mL, or 2.6% per household per week. The amount of sugar in those drinks was 8 g, or 2.7%, lower per household per week. Further studies should determine whether and how apparently small effect sizes translate into health outcomes. TRIAL REGISTRATION NUMBER: ISRCTN18042742.

Associations between social media, adolescent mental health, and diet: A systematic review.

Social media use is integral to many adolescents' lives. It brings benefits but can also have detrimental effects on both physical and mental health. We conducted a systematic review examining associations between social media use, adolescent mental health (including body image, self-esteem, stress, interpersonal relationships and loneliness, anxiety, and depressive symptoms), and dietary outcomes. Quantitative studies published between 2019 and 2023 investigating both mental health and diet were searched in 11 databases. The risk of bias was appraised using ROBINS-E. Data were narratively synthesized by type of association, PROGRESS-Plus health equity characteristics, and related to social media influencers. Twenty-one studies were included, of which only one focused on influencers. Sex/gender was the only equity characteristic assessed (n = 8), with mixed results. The findings suggest significant positive correlations between social media use and both depressive and disordered eating symptoms, body dissatisfaction, and anxiety. Four studies identified body image, self-esteem, or anxiety as moderators acting between social media exposure and dietary outcomes. Policy interventions mitigating the impact of social media on adolescents-particularly body image and disordered eating-are needed, alongside follow-up studies on causal pathways, the role of influencers, equity impacts, dietary intake, and the best measurement tools to use.

Learning from the CO-CREATE project: A protocol for systems thinking across research (STAR).

The CO-CREATE project aimed to work with young people to create, inform, and disseminate obesity-preventive evidence-based policies using a complex systems perspective. This paper draws lessons from this experience and proposes a protocol for embedding systems thinking within a research project. We first draw on existing systems thinking frameworks to analyze how systems thinking was translated across CO-CREATE, including the flow and relationship between the work packages and in the methods used. We then take the lessons from CO-CREATE and the principles of existing systems thinking frameworks-which focus on various points of intervention planning and delivery but not on research projects as a whole-to formulate a protocol for embedding systems thinking across a research project. Key lessons for future planning and delivery of systems-oriented research projects include incorporating "boundary critique" by capturing key stakeholder (adolescent) values and concerns; working to avoid social exclusion; ensuring methodological pluralism to allow for reflection and responsiveness (with methods ranging from group model building, Photovoice, and small group engagement); getting policy recipients to shape key questions by understanding their views on the critical drivers of obesity early on in the project; and providing opportunity for intraproject reflection along the way.

Co-creating obesity prevention policies with youth: Policy ideas generated through the CO-CREATE project.

Despite growing recognition of the importance of applying a systems lens to action on obesity, there has only been limited analysis of the extent to which this lens has actually been applied. The CO-CREATE project used a youth-led participatory action research approach to generate policy ideas towards the reduction of adolescent overweight and obesity across Europe. In order to assess the extent to which these youth-generated policy ideas take a systems approach, we analyzed them using the Intervention Level Framework (ILF). The ILF ascribes actions to one of five system levels, from Structural Elements, the least engaged with system change, up to Paradigm, which is the system's deepest held beliefs and thus the most difficult level at which to intervene. Of the 106 policy ideas generated by young people during the CO-CREATE project, 91 (86%) were categorized at the level of Structural Elements. This emphasis on operational rather than systems level responses echoes findings from a previous study on obesity strategies. Analyzing the distribution of systems level responses using the ILF has the potential to support more effective action on obesity by allowing identification of opportunities to strengthen systems level responses overall.

Designing a youth-led Dialogue Forum tool: The CO-CREATE experience.

While obesity prevention represents an established field of research, the inclusion of young people, who are regularly cited as an important priority group, are rarely actioned in long-term studies. This paper focuses on the development of a dialogue tool intended to tackle this issue, engaging, and eliciting insights on the theme of obesity prevention, by young people and for young people. As part of the CO-CREATE project, this tool was co-developed by designers, public health, and youth participation experts, researchers, and young people. Co-creation is a key methodology in the design of the dialogue tool, as young people were involved in all stages of the development process. This paper elaborates on the process of co-designing a dialogue tool that helps explore obesity prevention policy ideas from multiple perspectives, and describes the design principles that informed the process and the final versions of the tool. The purpose of the Dialogue Forum tool is for youth to engage policymakers and other relevant stakeholders to discuss and refine co-created and youth-initiated ideas for healthier food and physical activity environments. We analyze how specific design principles were integrated into different prototypes and the value of this within the project and the field.

Adolescents' capacity to take action on obesity: A concurrent controlled before-and-after study of the European CO-CREATE project.

This study evaluated the effect on reported readiness for action and attitudes toward obesity prevention among older adolescents (mean age 17) who took part in a youth-led participatory action research European initiative (CO-CREATE Youth Alliances) compared with a comparison group that acted as controls. This was a concurrent before-and-after controlled study across five countries and took place between September 2019 and October 2020. Adolescents (n = 159) recruited from schools and youth organizations came together with researchers and formed 15 Youth Alliances. An online questionnaire measuring their readiness for action and attitudes toward obesity prevention was administered. Alliance members (n = 62) who filled in the questionnaire at both baseline and postinitiative, and adolescents from the comparison group (n = 132) who completed the questionnaire twice were included in the main analysis. Two-level linear mixed models controlling for country-related variance were fitted. Alliance members scored significantly higher than the comparison group on two factors in each of the readiness for action, responsibility, and drivers of behavior concepts. The findings suggest that involving youth in co-creating policies to prevent obesity may increase adolescents' readiness for action and promote a shift in adolescents' conceptualization of obesity from an individual perspective to a societal responsibility and drivers of behavior.

What policies are there and what policies are missing? A Photovoice study of adolescents' perspectives on obesity-prevention policies in their local environment.

The aim of this study was to investigate adolescents' critical awareness of whether obesity prevention policies targeting physical activity (PA) and nutrition were operating in their local community. Participants were 41 adolescents (aged 16-18, 90% women) recruited from three communities in Poland. Prior to this study, they were involved in obesity-prevention participatory initiatives (conducted within the CO-CREATE project), where obesity-related public policy limitations were analyzed in a youth-led discussion. A Photovoice exercise was designed to capture obesity-related public policies that were either present or absent in young people's local environments. The photographs (N = 213) were coded and mapped according to the policy themes they illustrated, using the MOVING and NOURISHING frameworks. The public policies represented in the photographs are most frequently related to: healthy retail or food service environments; food advertising or promotion; structures and surroundings that promote PA; and infrastructure and opportunities that support public or active transport. Adolescents are critically aware of the presence and lack of specific public policies operating in their local environment, particularly policies affecting structural aspects of food and PA environments. Policy-oriented photovoice exercises may prompt critical awareness among adolescents and empower them to contribute to obesity prevention policy processes.

Understanding the dynamics emerging from the interplay among poor mental wellbeing, energy balance-related behaviors, and obesity prevalence in adolescents: A simulation-based study.

Both obesity and poor mental wellbeing have a high prevalence in European youth. Adolescents in six countries identified mental wellbeing factors as main drivers of youth obesity through systems mapping. This study sought to (1) explore the dynamics of the interplay between poor mental wellbeing, energy balance-related behaviors, and adolescent overweight and obesity prevalence and (2) test the effect of intervention point scenarios to reduce adolescent obesity. Drawing on the youth-generated systems maps and a literature synthesis, we built a simulation model that represents the links from major feedback pathways for poor mental wellbeing to changes in dietary, physical activity, and sleep behaviors. The model was calibrated using survey data from Norway, expert input, and literature and shows a good fit between simulated behavior and available statistical data. The simulations indicate that adolescent mental wellbeing is harmed by socio-cultural pressures and stressors, which trigger reinforcing feedback mechanisms related to emotional/binge eating, lack of motivation to engage in physical activity, and sleep difficulty. Targeting a combination of intervention points that support a 25% reduction of pressure on body image and psychosocial stress showed potentially favorable effects on mental wellbeing-doubling on average for boys and girls and decreasing obesity prevalence by over 4%.

Encouraging greater empowerment for adolescents in consent procedures in social science research and policy projects.

The United Nations Convention on the Rights of the Child emphasizes the importance of allowing children and adolescents to influence decisions that are important to them following their age and maturity. This paper explores the principles, practices, and implications around using parental versus child/adolescent consent when participating in social science research and policy development. Experiences from two studies are presented: The Confronting Obesity: Co-creating policy with youth (CO-CREATE) and the Health Behaviour in School-aged Children (HBSC) study, a World Health Organization (WHO) Collaborative Cross-National study. Although parental consent may be an important gatekeeper for protecting children and adolescents from potentially harmful research participation, it may also be considered an obstacle to the empowerment of children and adolescents in case they want to share their views and experiences directly. This paper argues that evaluation of possible harm should be left to ethics committees and that, if no harm related to the research participation processes is identified and the project has a clear perspective on collaborating with the target group, adolescents from the age of 12 years should be granted the legal capacity to give consent to participate in the research project. Collaboration with adolescents in the development of the research project is encouraged.

Industry views of the UK Soft Drinks Industry Levy: a thematic analysis of elite interviews with food and drink industry professionals, 2018-2020.

OBJECTIVES: The UK Soft Drinks Industry Levy (SDIL), implemented in 2018, has been successful in reducing the sugar content and purchasing of soft drinks, with limited financial impact on industry. Understanding the views of food and drink industry professionals involved in reacting to the SDIL is important for policymaking. However, their perceptions of the challenges of implementation and strategic responses are unknown. The aim of this study, therefore, was to explore how senior food and drink industry professionals viewed the SDIL. DESIGN: We undertook a qualitative descriptive study using elite interviews. Data were analysed using Braun and Clarke's thematic analysis, taking an inductive exploratory and descriptive approach not informed by prior theory or frameworks. SETTING AND PARTICIPANTS: Interviews were conducted via telephone with 14 senior professionals working in the food and drink industry. RESULTS: Five main themes were identified: (1) a level playing field…for some; industry accepted the SDIL as an attempt to create a level playing field but due to the exclusion of milk-based drinks, this was viewed as inadequate, (2) complex to implement, but no lasting negative effects; the SDIL was complex, expensive and time consuming to implement, with industry responses dependent on leadership buy-in, (3) why us?-the SDIL unfairly targets the drinks industry; soft drinks are an unfair target when other categories also contain high sugar, (4) the consumer is king; consumers were a key focus of the industry response to this policy and (5) the future of the SDIL; there appeared to be a wider ripple effect, which primed industry to prepare for future regulation in support of health and environmental sustainability. CONCLUSIONS: Insights from senior food and drink industry professionals illustrate how sugar-sweetened beverage taxes might be successfully implemented and improve understanding of industry responses to taxes and other food and drink policies. TRIAL REGISTRATION NUMBER: ISRCTN18042742.

The use of participatory systems mapping as a research method in the context of non-communicable diseases and risk factors: a scoping review.

CONTEXT: Participatory systems mapping is increasingly used to gain insight into the complex systems surrounding non-communicable diseases (NCDs) and their risk factors. OBJECTIVES: To identify and synthesize studies that used participatory systems mapping in the context of non-communicable diseases. DESIGN: Scoping review. ELIGIBILITY CRITERIA: Peer-reviewed studies published between 2000 and 2022. STUDY SELECTION: Studies that focused on NCDs and/or related risk factors, and included participants at any stage of their system's mapping process, were included. CATEGORIES FOR ANALYSIS: The main categories for analysis were: (1) problem definition and goal-setting, (2) participant involvement, (3) structure of the mapping process, (4) validation of the systems map, and (5) evaluation of the mapping process. RESULTS: We identified 57 studies that used participatory systems mapping for a variety of purposes, including to inform or evaluate policies or interventions and to identify potential leverage points within a system. The number of participants ranged from 6 to 590. While policymakers and professionals were the stakeholder groups most often included, some studies described significant added value from including marginalized communities. There was a general lack of formal evaluation in most studies. However, reported benefits related mostly to individual and group learning, whereas limitations described included a lack of concrete actions following from systems mapping exercises. CONCLUSIONS: Based on the findings of this review, we argue that research using participatory systems mapping would benefit from considering three different but intertwined actions: explicitly considering how different participants and the power imbalances between them may influence the participatory process, considering how the results from a systems mapping exercise may effectively inform policy or translate into action, and including and reporting on evaluation and outcomes of the process, wherever possible.

The Health Economic Assessment Tool (HEAT) for walking and cycling - experiences from 10 years of application of a health impact assessment tool in policy and practice.

Introduction: In recent years, walking and cycling have moved into the focus as promising approaches to achieve public health, sustainable transport, climate goals and better urban resilience. However, they are only realistic transport and activity options for a large proportion of the population when they are safe, inclusive and convenient. One way to increase their recognition in transport policy is the inclusion of health impacts of walking and cycling into transport economic appraisals. Methods: The Health Economic Assessment Tool (HEAT) for walking and cycling calculates: if x people walk or cycle a distance of y on most days, what is the economic value of impacts on premature mortality, taking into account effects of physical activity, air pollution and road fatalities, as well as effects on carbon emissions. Different data sources were collated to examine how the HEAT in more than 10 years of existence, and to identify lessons learned and challenges. Results: Since its launch in 2009, the HEAT has gained wide recognition as a user friendly, yet robust, evidence-based tool usable by academics, policymakers, and practitioners. Originally designed for use in Europe, it has since been expanded for global use. Discussion: Challenges for a wider uptake of health-impact assessment (HIA) tools including active transport such as HEAT are the promotion and dissemination to local practitioners and policy makers also outside European and English-speaking regions and in low- and middle-income contexts, further increasing usability, and more generally the advancement of systematic data collection and impact quantification related to walking and cycling.

Correction: Anticipatory changes in British household purchases of soft drinks associated with the announcement of the Soft Drinks Industry Levy: A controlled interrupted time series analysis.

[This corrects the article DOI: 10.1371/journal.pmed.1003269.].