Assessing cost-effectiveness of obesity prevention policies in Australia

ACE-obesity policy 2018

13 Dec 2018

The current obesity epidemic in Australia and around the globe has significant negative health and economic consequences. Addressing this problem will require a comprehensive societal response, including implementation of a suite of multi-sectoral government policies. Informed government action requires reliable comparative evidence on the costs and benefits of various policy options.

ACE-Obesity Policy is a priority-setting study that aimed to evaluate the economic credentials of a range of obesity prevention policies (including both regulatory and program-based interventions), across multiple sectors and multiple areas of governance (local, state and federal governments, and the private sector). The study formed part of the broader body of work of the National Health and Medical Research Council funded Centre of Research Excellence in Obesity Policy and Food Systems (APP1041020: 2012-2018), and answered the research question: “What are the most effective, cost- effective, affordable and implementable policy options to prevent obesity across a range of settings?”

The Assessing Cost-Effectiveness (ACE) approach was adopted – characterised by the use of consistent, rigorous methods for the technical cost-effectiveness analyses (including extensive uncertainty analyses), alongside qualitative analyses of key implementation considerations relevant to policy decisions (strength of evidence, equity, acceptability, feasibility, and sustainability). The modelling of expected health benefits and related costs in response to an intervention was based on a previously developed proportional, multi-state, life table Markov model.

Key advancements made to the model as part of the ACE-Obesity Policy study included:

  • the integration of physical activity and fruit and vegetables intake as risk factors (in addition to body mass index);
  • the development of an equity-focused version of the model that allowed the quantification of the differential cost, health and cost-effectiveness outcomes across different socio-economic position (SEP) groups; and modifications to allow better quantification of interventions targeted at children.

Intervention selection was based on a deliberative process that included consideration of:

  1. the potential impact on addressing obesity in Australia;
  2. the relevance to current policy decision-making; and
  3. the availability of evidence for intervention effectiveness.

Full economic evaluations were conducted for 16 interventions, with 50 different scenarios explored. Evidence reviews were completed for a further 12 interventions, but full economic modelling was not conducted due to the lack of evidence for effectiveness required to complete a robust evaluation.

ACE-Obesity Policy is a priority- setting study that aimed to evaluate the economic credentials of a range of obesity prevention policies across multiple sectors and multiple areas of governance.

Effective action to prevent obesity will not be possible without strong governmental leadership and commitment.

All 16 interventions were found to be cost-effective approaches to addressing obesity in the Australian population. Eleven of these interventions were estimated to produce health benefits and save costs in the long term (classified as ‘dominant’). The five remaining interventions were estimated to produce health benefits at a cost well below the common decision threshold used in Australia (classified as ‘cost-effective’). Extensive uncertainty, threshold and scenario analyses showed that results were robust to changes in intervention-specific key input variables and assumptions.

An intervention to increase the price of alcohol through a uniform volumetric tax performed best in terms of its cost-effectiveness credentials and health benefits. This intervention has not previously been evaluated as an obesity prevention measure. Regulations to tax sugar-sweetened beverages and restrict television advertising of unhealthy foods ranked second and third on the cost- effectiveness league table, and have both been recommended by authoritative obesity prevention reports and health promotion bodies as key components of an obesity prevention strategy. This study is the first to evaluate the cost-effectiveness of several other promising obesity prevention interventions such as: restrictions on price promotions of unhealthy foods; supermarket shelf-tags on healthier products; and workplace interventions to reduce sedentary behaviour.

The vast majority (seven out of nine) regulatory interventions evaluated were dominant, compared to around half (four out of seven) of the program-based interventions. These differences were largely driven by the increased implementation costs of program-based interventions. However, the modelling of program-based interventions was generally based on stronger evidence for intervention effectiveness. Due to limitations in the current state of the evidence, the modelling of many of the regulatory interventions was based on their demonstrated impact on dietary and physical activity outcomes; their likely impact on body weight was generally based on the assumption that diet and physical activity outcomes are sustained without compensatory behaviour.

Two interventions (related to taxing sugar-sweetened beverages, and restricting television advertising of unhealthy foods) were quantitatively evaluated for their impact on equity. Both evaluations found a positive impact on equity of health outcomes, with higher health gains in the lower SEP groups. The qualitative assessment that included a judgement on both process and outcome dimensions of equity, found that many of the most cost-effective interventions also resulted in higher out-of-pocket costs relative to income for lower SEP groups.

Governments need to consider the design of obesity prevention interventions to ensure inequities are not exacerbated (e.g., hypothecation of taxes to benefit those in special need and from lower SEP groups).

Effective action to prevent obesity will not be possible without strong governmental leadership and commitment. Challenges will arise from the following:

  1. Several interventions evaluated in this study may reduce specific company profits resulting in low levels of industry acceptability.
  2. Many of the health benefits and cost-savings may only materialise in the longer term (i.e., beyond any single political cycle).
  3. Many of the recommended interventions are cross-sectoral in nature, and successful implementation will require a whole-of-government approach with inter-departmental co- operation and co-ordination.
  4. Broad-based societal support for obesity prevention needs to be mobilised.

Despite these challenges, the great potential for substantial health benefits stemming from the obesity prevention interventions evaluated in this study can be used to garner a coalition of support for these policies.

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