ABSTRACT

This paper opens a discussion on the main features of an investment case for obesity prevention and control, by scanning available evidence on existing approaches and by highlighting contextual considerations and evidence for Latin America and the Caribbean. We call on researchers and analysts in the field to update and broaden existing methods of economic analyses to better reflect the multisectoral nature of an investment case for obesity prevention and control. We also identify research gaps and further work required to advance methods and evidence towards investment cases throughout the Americas.

Keywords
Cost-benefit analysis; obesity; investments; health economics; health policy; Americas

RESUMEN

Este artículo abre un debate sobre las principales características de los argumentos a favor de la inversión para prevenir y controlar la obesidad, al buscar evidencia sobre los métodos existentes y destacar las consideraciones relativas al contexto y la evidencia para América Latina y el Caribe. Instamos a los investigadores y analistas en el campo a que actualicen y amplíen los métodos existentes de análisis económico a fin de reflejar mejor la naturaleza multisectorial de los argumentos a favor de la inversión para la prevención y el control de la obesidad. También encontramos lagunas en la investigación y el trabajo adicional que se requiere para impulsar los métodos y la evidencia que respalden estos argumentos a favor de la inversión en toda América.

Palabras clave
Análisis costo-beneficio; obesidad; inversiones en salud; economía de la salud; política de salud; Américas

RESUMO

Esta análise visa trazer à discussão as principais características de um caso de investimento para prevenção e controle da obesidade ao examinar comprovações sobre os enfoques existentes e destacar considerações contextuais e evidências para a América Latina e o Caribe. Fazemos um chamado aos pesquisadores e analistas no campo a atualizar e expandir a metodologia atual de análise econômica a fim de melhor refletir o caráter multissetorial de um caso de investimento para prevenção e controle da obesidade. Também identificamos lacunas de pesquisa e a necessidade de trabalhar mais para melhorar a metodologia e as evidências de casos de investimento nas Américas.

Palavras-chave
Análise custo-benefício; obesidade; investimentos em saúde; economia da saúde; política de saúde; Américas

As the obesity epidemic has been spreading rapidly across the Americas, national governments and regional and international organizations have called for action from the whole of society (¹1. Pan American Health Organization. Plan of Action for the Prevention of Obesity in Children and Adolescents. Washington, D.C.: PAHO; 2015. Available at: http://www.paho.org/hq/index.php?option=com_content&view=article&id=11373%3Aplan-of-action-prevention-obesity-children-adolescents&catid=8358%3Aobesity&Itemid=4256&lang=en Accessed 15 January 2018.
http://www.paho.org/hq/index.php?option=... –⁴4. Barquera S, Campos I, Rivera JA. Mexico attempts to tackle obesity: the process, results, push backs and future challenges. Obes Rev. 2013;14(S2):69–78.). To answer these calls, jurisdictions are seeking comprehensive investment cases that would articulate the benefits and costs of an intervention strategy across various economic actors and the factors that could affect its implementation. For example, the United Nations Interagency Task Force on the Prevention and Control of Noncommunicable Diseases has been working with countries around the globe to prepare investment cases for prevention and control of noncommunicable diseases (NCDs) and their risk factors (⁵5. World Health Organization. UN Interagency Task Force on NCDs (UNIATF). Available at: http://www.who.int/ncds/un-task-force/en/ Accessed 15 January 2018
http://www.who.int/ncds/un-task-force/en... ).

An investment case presents reasoning for an action and includes a strategy to achieve a stated objective. Drawing from recent efforts to formulate investment cases (⁵5. World Health Organization. UN Interagency Task Force on NCDs (UNIATF). Available at: http://www.who.int/ncds/un-task-force/en/ Accessed 15 January 2018
http://www.who.int/ncds/un-task-force/en... –⁷7. World Health Organization. Investing in mental health: evidence for action. Geneva: WHO; 2013.), we find that a public health investment case generally includes six steps: 1) describing the problem within a given country, including determinants and risk factors and public health and economic impacts; 2) identifying effective, feasible, and locally relevant interventions for analysis; 3) providing analysis of the costs versus benefits of intervening, and identifying synergies among interventions; 4) building a package of interventions based on the second and third steps as well as other criteria such as distributional consequences and acceptability among stakeholders; 5) identifying the funding requirements and finding resources; and 6) developing a detailed plan for implementation and evaluation of results. Figure 1 summarizes this process.

The objective of this paper is to discuss how various economic methods for valuing costs and benefits can be applied to obesity-targeted interventions (the third step listed above). The paper also summarizes major evidence towards the development of an investment case for obesity prevention and control in line with the third and fourth steps. In addition, research gaps in methods and evidence are underscored, and ways forward are proposed.

It should be noted that this paper is not a systematic literature review, but rather a scoping review of methodologies and the evidence supporting them.

METHODS OF ECONOMIC EVALUATION OF INTERVENTIONS

Social cost-benefit analysis as a conceptual framework

Economic analyses can assess whether a policy response is required from the efficiency perspective. For example, the analyses can identify market failures in efficient resource allocation, as well as whether such failures are amenable to intervention (⁸8. Ellis VL, Milliken OV. Integrating economics into the rationale for multisectoral action on obesity. Rev Panam Salud Publica. 2018;42:e58. https://doi.org/10.26633/RPSP.2018.58
https://doi.org/10.26633/RPSP.2018.58... ). Further, economic evaluation, both prospective and experiential, can inform on a range of interventions. Note that in this paper we refer to an economic evaluation as either a prospective or retrospective “comparative analysis of alternative courses of action in terms of both their costs and consequences” (⁹9. Drummond MF, Sculpher GL, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the economic evaluation of health care programmes. 3d ed. New York: Oxford University Press; 2005.).

A social cost-benefit analysis (SCBA) is a general economic framework used to examine which interventions, or intervention package, bring the highest socioeconomic return. Under SCBA, social welfare (well-being) is some measure of the well-being of all individuals in the economy. As individuals maximize their own overall well-being, rather than health alone, SCBA takes a broad perspective, under which societal health-related goals are balanced with that of the consumption of goods and services, including food, beverages, and physical activity.

In the most comprehensive case of SCBA, costs and benefits are presented in monetary units, allowing various benefits to be added together and compared with costs associated with the intervention(s). Also, using common currency allows analyses of benefits to various economic actors, including central ministries and nonhealth stakeholders. Lifetime costs and benefits are usually discounted to a base year, to assess the present value of total multiyear benefits and costs. An intervention to address obesity is desirable from a society's viewpoint if the present value of total benefits outweighs that of the intervention costs (⁹9. Drummond MF, Sculpher GL, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the economic evaluation of health care programmes. 3d ed. New York: Oxford University Press; 2005.).

Health benefits can be described as: 1) a direct contribution to well-being (intrinsic value of health); 2) greater productivity; 3) greater longevity; and 4) greater engagement in society, including volunteering (¹⁰10. World Health Organization. Economic evaluation of childhood obesity. In: World Health Organization. Consideration of the evidence on childhood obesity for the Commission on Ending Childhood Obesity: report of the Ad Hoc Working Group on Science and Evidence for Ending Childhood Obesity, Geneva, Switzerland. Geneva: WHO; 2016:37–43. Available at: http://apps.who.int/iris/bitstream/10665/206549/1/9789241565332_eng.pdf Accessed 15 January 2018.
http://apps.who.int/iris/bitstream/10665... ). A range of methods to value health or life can be employed, including a value of statistical life (VSL) approach under either a revealed preference or a contingent valuation (willingness to pay) method. In principle, a VSL approach measures all four of those health benefits.

Costs of an intervention include implementation costs, but also economic losses attributable to an intervention (such as financial losses to a food industry or job layoffs due to a labeling regulation or due to a tax). Also, resources saved in health care, enhanced productivity, etc., that are attributed to the intervention are subtracted from costs (⁹9. Drummond MF, Sculpher GL, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the economic evaluation of health care programmes. 3d ed. New York: Oxford University Press; 2005.).

As a gold standard of economic evaluation, a comprehensive SCBA has high information requirements that may not be achievable in each practical application. Particularly, the search for methods to value benefits of improved health is ongoing, underscoring the difficulties of this task (¹¹11. Brazier J, Ratcliffe J, Saloman J, Tsuchiya A. Measuring and valuing health benefits for economic evaluation. New York: Oxford University Press; 2017.). The value of health cannot be directly assessed from market prices, and likely is best derived from a combination of an assessment of individual preferences and professional opinion (⁹9. Drummond MF, Sculpher GL, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the economic evaluation of health care programmes. 3d ed. New York: Oxford University Press; 2005., ¹⁰10. World Health Organization. Economic evaluation of childhood obesity. In: World Health Organization. Consideration of the evidence on childhood obesity for the Commission on Ending Childhood Obesity: report of the Ad Hoc Working Group on Science and Evidence for Ending Childhood Obesity, Geneva, Switzerland. Geneva: WHO; 2016:37–43. Available at: http://apps.who.int/iris/bitstream/10665/206549/1/9789241565332_eng.pdf Accessed 15 January 2018.
http://apps.who.int/iris/bitstream/10665... ). When valuation information is incomplete or estimates vary widely, sensitivity analysis can assess the robustness of the SCBA.

Applications of social cost-benefit analysis

Based on a general SCBA framework, various applications and protocols have been developed, such as cost-utility analysis (CUA), cost-effectiveness analysis (CEA), and social return on investment (SROI) (⁹9. Drummond MF, Sculpher GL, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the economic evaluation of health care programmes. 3d ed. New York: Oxford University Press; 2005., ¹²12. Banke-Thomas AO, Madaj B, Charles A, van den Broek N. Social return on investment (SROI) methodology to account for value for money of public health interventions: a systematic review. BMC Public Health. 2015;15(1):582., ¹³13. UK Cabinet Office, The Office of the Third Sector. A guide to social return on investment 2012. Available at: https://www.bond.org.uk/data/files/Cabinet_office_A_guide_to_Social_Return_on_Investment.pdf Accessed 8 January 2018.
https://www.bond.org.uk/data/files/Cabin... ) (Table 1). These represent versions of an SCBA that forgo comprehensiveness for tractability, standardization, or verifiability. However, by simplifying, such applications can introduce bias or ignore broad impacts.

Cost-effectiveness and cost-utility analyses. CEAs/CUAs of obesity prevention and management interventions dominate the field. They allow the comparison of costs and benefits of an intervention with that of a status quo or of a different intervention. In a health-related CEA, benefits are often measured in life years saved or changes in body mass index (BMI). In a CUA, quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs) are used, which compared to a CEA, adds the quality-of-life dimension into the outcome (¹⁴14. Sassi F. Calculating QALYs, comparing QALY and DALY calculations. Health Policy Plan. 2006;21(5):402–8.). As CEAs and CUAs evaluate benefits in units of health rather than placing a society's value on these units, these analyses only account indirectly for the first and third benefits mentioned above. Also, CUAs and CEAs cannot formally integrate the second and fourth benefits.

In general, CEAs and CUAs work well when a single sector's perspective is used and intervention effects are contained within this sector, such as replacing an existing pharmaceutical with a more potent one. Despite their wide usage for in-health-sector analyses, these methods are not commonly used by other sectors (e.g., agriculture, environment, transport), even for decisions related to human health (¹⁵15. Food and Agriculture Organization of the United Nations. Tool for designing, monitoring and evaluating land administration programmes in Latin America. Available at: http://www.fao.org/in-action/herramienta-administracion-tierras/module-5/practical-evaluation-guide/introduction-cba/en/ Accessed 8 January 2018.
http://www.fao.org/in-action/herramienta... –¹⁷17. Navrud S, Lindhem H. Valuing mortality risk reduction in regulatory analysis of environmental, health and transport policies: policy implications. Available at: http://www.oecd.org/env/tools-evaluation/49447312.pdf Accessed 8 January 2018.
http://www.oecd.org/env/tools-evaluation... ).

Compared to the SCBA, CEA/CUA frameworks can neither account for multisectoral benefits evaluated by different metrics (e.g., dollars, QALYs, days of sick leave, years of education) in a single measure nor directly compare the costs against the benefits of an intervention to determine whether the intervention is worth pursuing. Instead, the decision regarding whether the intervention improves upon the status quo is based on a comparison with a subjective threshold of cost-effectiveness (e.g., acceptable number of dollars spent per QALY). The implications of the arbitrary nature and narrow focus of cost-effectiveness thresholds have been discussed elsewhere (⁹9. Drummond MF, Sculpher GL, Torrance GW, O'Brien BJ, Stoddart GL. Methods for the economic evaluation of health care programmes. 3d ed. New York: Oxford University Press; 2005.).

Social return on investment. Compared to CEA and CUA, the SROI approach has the capacity to measure broader socioeconomic and environmental benefits of interventions. Benefits to intervention beneficiaries as well as to relevant stakeholders are measured using financial proxies (¹³13. UK Cabinet Office, The Office of the Third Sector. A guide to social return on investment 2012. Available at: https://www.bond.org.uk/data/files/Cabinet_office_A_guide_to_Social_Return_on_Investment.pdf Accessed 8 January 2018.
https://www.bond.org.uk/data/files/Cabin... ) and are compared to costs of intervening. SROI is much less commonly used for interventions in public health (¹²12. Banke-Thomas AO, Madaj B, Charles A, van den Broek N. Social return on investment (SROI) methodology to account for value for money of public health interventions: a systematic review. BMC Public Health. 2015;15(1):582.) than are CEA and CUA, and the SROI method for public health is not yet well established. Issues remain regarding whose benefits should be accounted for, the choice of financial proxies to monetize benefits, and the attribution of effects/benefits of the intervention (¹²12. Banke-Thomas AO, Madaj B, Charles A, van den Broek N. Social return on investment (SROI) methodology to account for value for money of public health interventions: a systematic review. BMC Public Health. 2015;15(1):582.).

Macroeconomic analyses

Macroeconomic models, in particular general equilibrium or partial equilibrium models, can assess sectoral and economy-wide costs and benefits resulting from obesity prevention interventions. They are well suited for forecasting the economy-wide or sectoral effects of interventions (¹⁸18. Astolfi R, Lorenzoni L, Oderkirk J. Informing policy makers about future health spending: a comparative analysis of forecasting methods in OECD countries. Health Policy. 2012;107(1):1–10.). Examples of such effects include job losses as a result of a shrinking demand for unhealthy products, impacts on trade and agriculture due to a shift in demand for certain foods, and a healthier workforce.

AVAILABLE EVIDENCE OF COSTS AND BENEFITS

Evidence of the economic cost of obesity

Although economic cost estimates alone are insufficient for developing an investment case for obesity prevention and control, they can describe the size of the pre-intervention impact of obesity as well as the potential savings as a result of intervention strategies. Unfortunately, evidence describing the economic cost of obesity for the Americas is sparse, with the exceptions of Canada and the United States of America (¹⁹19. Tremmel M, Gerdtham U, Nilsson PM, Saha S. Economic burden of obesity: a systematic literature review. Int J Environ Res Public Health. 2017;14(4):435.). Further, the information is largely limited to impacts on health care expenditures. The most recent systematic review suggests a wide range of estimates of obesity-attributed health care costs in Latin America, from 0.1% to 14% of total health care expenditures, depending on the country and study. For example, this estimate was 3.2% for Brazil in 2013 and 2.1% for Chile in 2014 (²⁰20. Cuadrado C. Projecting costs of obesity in Chile (and Latin-America): data and method issues. Presentation at: Advancing Economics for the Prevention and Control of NCDs in the Americas; Washington, D.C.; 2016 Aug 31–Sept 1.). For Canada, the most recent estimates are 1.7% (²¹21. Anis AH, Zhang W, Bansback N, Guh D, Amarsi Z, Birmingham C. Obesity and overweight in Canada: an updated cost-of-illness study. Obes Rev. 2010;11(1):31–40.) and 2.6% (²²22. Krueger H, Turner D, Krueger J, Ready AE. The economic benefits of risk factor reduction in Canada: tobacco smoking, excess weight and physical inactivity. Can J Public Health. 2014;105(1):e69-e78.), whereas for the United States, the range is 5% to 10% (²³23. Tsai AG, Williamson DF, Glick HA. Direct medical cost of overweight and obesity in the USA: a quantitative systematic review. Obes Rev. 2011;12(1):50–61.).

The worldwide available evidence on productivity losses due to premature mortality and sickness absences attributed to obesity indicates that these are at least as high as health care expenditures due to obesity (²⁴24. Dee A, Kearns K, O'Neill C, Sharp L, Staines A, O'Dwyer V, et al. The direct and indirect costs of both overweight and obesity: a systematic review. BMC Res Notes. 2014;7(1):242.). Few of these estimates are available for the Americas, with the exception of Canada and the United States (²⁵25. Trogdon J, Finkelstein E, Hylands T, Dellea P, Kamal-Bahl S. Indirect costs of obesity: a review of the current literature. Obes Rev. 2008;9(5):489–500.). Two studies for Mexico estimate productivity losses at 0.11% and 0.42% of gross domestic product (GDP), while a study for Argentina puts the figures at 0.02% of GDP (²⁰20. Cuadrado C. Projecting costs of obesity in Chile (and Latin-America): data and method issues. Presentation at: Advancing Economics for the Prevention and Control of NCDs in the Americas; Washington, D.C.; 2016 Aug 31–Sept 1.). Other economic effects of obesity, such as impacts on social protection programs, human capital development and education, employment, and nonpaid work, have received only cursory attention (¹⁰10. World Health Organization. Economic evaluation of childhood obesity. In: World Health Organization. Consideration of the evidence on childhood obesity for the Commission on Ending Childhood Obesity: report of the Ad Hoc Working Group on Science and Evidence for Ending Childhood Obesity, Geneva, Switzerland. Geneva: WHO; 2016:37–43. Available at: http://apps.who.int/iris/bitstream/10665/206549/1/9789241565332_eng.pdf Accessed 15 January 2018.
http://apps.who.int/iris/bitstream/10665... , ²⁶26. Smith E, Hay P, Campbell L, Trollor JN. A review of the association between obesity and cognitive function across the lifespan: implications for novel approaches to prevention and treatment. Obes Rev. 2011;12(9):740–55.).

Addressing obesity is a particular challenge for countries that, until recently, have targeted undernutrition. As the epidemiological transition progresses through the Americas, many countries are now experiencing a double burden of malnutrition, where stunting and micronutrient deficiencies take place together with increasing obesity rates (²⁷27. Etienne CF. Malnutrition in the Americas: challenges and opportunities. Rev Panam Salud Publica. 2016;40(2):102–3.). A 2017 study by the Economic Commission for Latin America and the Caribbean (ECLAC) and the World Food Program (WFP) found that in Ecuador and Mexico, respectively, the economic burden of malnutrition (lost productivity, reduced schooling, and elevated health care expenditures) is 4.3% and 2.3% of GDP. In these two countries, the burden of malnutrition is comprised mostly of losses due to stunting, which remain 1.5 to 3 times higher than that due to overnutrition/overweight. In contrast, the ECLAC/WFP study found that, while stunting is considered eradicated in Chile, the country faces a rising economic burden of overnutrition/overweight, representing 0.2% of GDP (²⁸28. Economic Commission for Latin America and the Caribbean; World Food Programme. The cost of the double burden of malnutrition: social and economic impact. Summary of the pilot study in Chile, Ecuador and Mexico. Available at: http://es.wfp.org/sites/default/files/es/file/english_pilotstudy_april_2017.pdf Accessed 15 January 2018.
http://es.wfp.org/sites/default/files/es... ). Moreover, adverse obesity outcomes may be worsened by associated deficiencies of iron, vitamin B12, vitamin D, and other micronutrients (²⁹29. Krzizek E, Brix JM, Herz CT, Kopp HP, Schernthaner G, Schernthaner G, et al. Prevalence of micronutrient deficiency in patients with morbid obesity before bariatric surgery. Obes Surg. 2018;28(3):643–8., ³⁰30. Via M. The malnutrition of obesity: micronutrient deficiencies that promote diabetes. ISRN Endocrinol. 2012;2012:103472. doi: 10.5402/2012/103472.
https://doi.org/10.5402/2012/103472... ), impacting disease progression and health care costs.

Although alarming, the obesity cost estimates presented above do not in themselves guide decisionmakers to an acceptable, feasible, efficient policy response. Further, the cost estimates cannot be directly translated into benefits or resource savings due to obesity interventions, but these estimates can inform assessments of potential savings.

Evidence of cost-utility and cost-effectiveness analyses and of valuations of benefits

Once the decision to intervene in order to correct market inefficiencies is made (⁸8. Ellis VL, Milliken OV. Integrating economics into the rationale for multisectoral action on obesity. Rev Panam Salud Publica. 2018;42:e58. https://doi.org/10.26633/RPSP.2018.58
https://doi.org/10.26633/RPSP.2018.58... ), policymakers need a list of interventions to choose from to create a package of measures. Such interventions have to be both effective and provide good value for money (be efficient) in a particular context. As described above, CEAs/CUAs are often used to assess the efficiency of a single intervention compared to an alternative. In general, only health-related benefits are considered, thus the perspective is essentially of a health sector, despite a general recognition that obesity needs to be addressed beyond the health sector. McKinnon et al. (³¹31. McKinnon RA, Siddiqi SM, Chaloupka FJ, Mancino L, Prasad K. Obesity-related policy/environmental interventions: a systematic review of economic analyses. Am J Prev Med. 2016;50(4):543–49.) provide the most recent systematic review of CEA/CUA of obesity prevention worldwide, while Lehnert et al. (³²32. Lehnert T, Sonntag D, Konnopka A, Riedel-Heller S, König H. The long-term cost-effectiveness of obesity prevention interventions: systematic literature review. Obes Rev. 2012;13(6):537–53.) review evidence for countries of the Organization for Economic Cooperation and Development (OECD). Others have conducted systematic reviews of economic evaluations (mostly CEAs/CUAs) of childhood obesity-related interventions (³³33. Döring N, Mayer S, Rasmussen F, Sonntag D. Economic evaluation of obesity prevention in early childhood: methods, limitations and recommendations. Int J Environ Res Public Health. 2016;13(9):911.–³⁵35. John J, Wolfenstetter SB, Wenig CM. An economic perspective on childhood obesity: recent findings on cost of illness and cost effectiveness of interventions. Nutrition. 2012;28(9):829–39.). Interventions included in those reviews (³¹31. McKinnon RA, Siddiqi SM, Chaloupka FJ, Mancino L, Prasad K. Obesity-related policy/environmental interventions: a systematic review of economic analyses. Am J Prev Med. 2016;50(4):543–49.–³⁵35. John J, Wolfenstetter SB, Wenig CM. An economic perspective on childhood obesity: recent findings on cost of illness and cost effectiveness of interventions. Nutrition. 2012;28(9):829–39.) were in the areas of community and built environment, nutrition-related policy/education changes, the school environment, and social marketing and media. Many studies in the reviews found beneficial economic outcomes of interventions. However, while many studies reported in the reviews modeled long-term impacts, most of the experienced-based assessments were from trials or observational studies over a relatively short horizon. Evidence of the long-term impact of interventions remains a research gap.

Countries of Latin America and the Caribbean (LAC) have been planning and piloting population-wide and targeted policy responses to obesity (³⁶36. Kline L, Jones-Smith J, Jaime Miranda J, Pratt M, Reis R, Rivera J, et al. A research agenda to guide progress on childhood obesity prevention in Latin America. Obes Rev. 2017;18(S2):19–27., ³⁷37. University of the West Indies; Caribbean Public Health Agency; Healthy Caribbean Coalition; University of Toronto. Accelerating action on NCDs. Evaluation of the 2007 CARICOM heads of government Port of Spain NCD summit declaration. Report on behalf of PAHO/WHO and CARICOM. Available at: http://onecaribbeanhealth.org/wp-content/uploads/2016/10/ACCELERATING-ACTION-ON-NCDS-POSDEVAL-Report-1.pdf Accessed 8 January 2018.
http://onecaribbeanhealth.org/wp-content... ). However, rigorous evaluations of effectiveness of those LAC obesity prevention and control measures have been sparse. Emerging evidence includes evaluations of a tax on sugar-sweetened beverages in Mexico (³⁸38. Colchero MA, Rivera-Dommarco J, Popkin BM, Ng SW. In Mexico, evidence of sustained consumer response two years after implementing a sugar-sweetened beverage tax. Health Aff (Millwood). 2017 Mar 1;36(3):564–571.), school-based programs in Latin America (³⁹39. Lobelo F, Garcia de Quevedo I, Holub CK, Nagle BJ, Arredondo EM, Barquera S, et al. School-based programs aimed at the prevention and treatment of obesity: evidence-based interventions for youth in Latin America. J Sch Health. 2013;83(9):668–77.), obesity treatment interventions for children in Latin America (⁴⁰40. Nagle BJ, Holub CK, Barquera S, Sánchez-Romero LM, Eisenberg CM, Rivera-Dommarco JA, et al. Interventions for the treatment of obesity among children and adolescents in Latin America: a systematic review. Salud Publica Mex. 2013;55:434–40.), and physical activity interventions (⁴¹41. Salvo D, Reis RS, Sarmiento OL, Pratt M. Overcoming the challenges of conducting physical activity and built environment research in Latin America: IPEN Latin America. Prev Med. 2014;69:S86–S92.). Given the sparseness of evidence, earlier comprehensive nationwide studies, such as the 2010 CEA study by OECD and the World Health Organization (WHO) (⁴²42. Cecchini M, Sassi F, Lauer JA, Lee YY, Guajardo-Barron V, Chisholm D. Tackling of unhealthy diets, physical inactivity, and obesity: health effects and cost-effectiveness. Lancet. 2010;376(9754):1775–84.) for Mexico and Brazil, used global evidence on intervention effectiveness rather than evidence specific to the Americas. Similarly, the WHO menu of cost-effective interventions on noncommunicable diseases given in Appendix 3 of the Global Action Plan for the Prevention and Control of Noncommunicable Diseases 2013–2020 (⁴³43. World Health Organization. Updating Appendix 3 of the Global NCD Action Plan 2013–2020. Available at: http://www.who.int/ncds/governance/appendix3-update/en/ Accessed 10 November 2017.
http://www.who.int/ncds/governance/appen... ) is based on the global evidence of intervention effectiveness, for the most part in developed countries (⁴⁴44. World Health Organization. Consultation on Updating Appendix 3 of the Global NCD Action Plan 2013–2020. Available at: http://who.int/nmh/events/meeting-report-consultation-on-appendix-3-final.pdf?ua=1 Accessed 10 November 2017.
http://who.int/nmh/events/meeting-report... ), rather than region- or country-specific evidence.

Further information on effectiveness and on intervention efficiency as provided by SCBA, CEA, or CUA is needed. Currently, CEA/CUA evidence for LAC countries is extremely limited (²2. Caribbean Public Health Agency. Safeguarding our future development. Plan of action for promoting healthy weights in the Caribbean: Prevention and control of childhood obesity 2014–2019. Available at: http://carpha.org/downloads/HealthyWeights.pdf Accessed 15 January 2018.
http://carpha.org/downloads/HealthyWeigh... , ⁴4. Barquera S, Campos I, Rivera JA. Mexico attempts to tackle obesity: the process, results, push backs and future challenges. Obes Rev. 2013;14(S2):69–78., ³⁶36. Kline L, Jones-Smith J, Jaime Miranda J, Pratt M, Reis R, Rivera J, et al. A research agenda to guide progress on childhood obesity prevention in Latin America. Obes Rev. 2017;18(S2):19–27., ⁴⁵45. Barquera S. Obesity prevention. Salud Publica Mex. 2013;55 Suppl 3:356., ⁴⁶46. Montes F, Sarmiento OL, Zarama R, Pratt M, Wang G, Jacoby E, et al. Do health benefits outweigh the costs of mass recreational programs? An economic analysis of four Ciclovía programs. J Urban Health. 2012;89(1):153–70.).

The importance of valuing the benefits of obesity treatment and prevention in monetary units has been recognized, particularly to enable multisectoral analyses. However, only a few examples of such valuations exist, including for the United States (⁴⁷47. Cawley J. Contingent valuation analysis of willingness to pay to reduce childhood obesity. Econ Hum Biol. 2008;6(2):281–92.), Germany (⁴⁸48. Kesztyüs D, Lauer R, Schreiber AC, Kesztyüs T, Kilian R, Steinacker JM. Parents' willingness to pay for the prevention of childhood overweight and obesity. Health Econ Rev. 2014;4(1):20.), and Taiwan (⁴⁹49. Fu T, Lin Y, Huang CL. Willingness to pay for obesity prevention. Econ Hum Biol. 2011;9(3):316–24.). As for valuing benefits of healthy populations in general, several approaches have been offered (“full income,” “value of lost output,” and “value of life”), and their applications are emerging (⁵⁰50. World Economic Forum; Bain & Company. Maximizing healthy life years: investments that pay off. Available at: http://www3.weforum.org/docs/WEF_Maximizing_Healthy_Life_Years.pdf Accessed 15 January 2018.
http://www3.weforum.org/docs/WEF_Maximiz... ). Outside the health sector, guidance exists to incorporate and value health impacts using a diversity of methods within the SCBA framework, e.g., willingness to pay (¹⁶16. National Center for Environmental Economics, Office of Policy, U.S. Environmental Protection Agency. Guidelines for preparing economic analyses 2014. Available at: https://www.epa.gov/environmental-economics/guidelines-preparing-economic-analyses Accessed 15 January 2018.
https://www.epa.gov/environmental-econom... , ⁵¹51. HM Treasury. The Green Book; appraisal and evaluation in central government. Available at: https://www.gov.uk/government/publications/the-green-book-appraisal-and-evaluation-in-central-governent Accessed 15 January 2018.
https://www.gov.uk/government/publicatio... ).

Complementary economic evidence

A limited number of projects worldwide have attempted to evaluate impacts of nutrition-related policies on GDP and economic sectors. Mukhopadhyay and Thomassin (⁵²52. Mukhopadhyay K, Thomassin PJ. Economic impact of adopting a healthy diet in Canada. J Public Health. 2012;20(6):639–652.) studied the impact of changes in Canadians' diet on Canada's export and import of meat, dairy products, and fruits and vegetables. The OECD (⁵³53. Organisation for Economic Co-operation and Development. The market implications of reduced sugar consumption. (Agriculture Policy Note March 2017). Available at: https://www.oecd.org/tad/policynotes/The-market-implications-of-reduced-sugar-consumption.pdf Accessed 15 January 2018.
https://www.oecd.org/tad/policynotes/The... ) examined the impact of a reduction in sugar on the agriculture sector and trade. Srinivasan et al. (⁵⁴54. Srinivasan CS, Irz X, Shankar B. An assessment of the potential consumption impacts of WHO dietary norms in OECD countries. Food Policy. 2006;31(1):53–77.) quantified and valued the consumption impact of implementing WHO dietary norms. A World Economic Forum (WEF) report (⁵⁰50. World Economic Forum; Bain & Company. Maximizing healthy life years: investments that pay off. Available at: http://www3.weforum.org/docs/WEF_Maximizing_Healthy_Life_Years.pdf Accessed 15 January 2018.
http://www3.weforum.org/docs/WEF_Maximiz... ) provides examples of case studies that applied an SROI approach, including a grant for nutrition improvement in Singapore and its effect on coronary diseases. With this nutrition grant, benefits in QALYs were monetized using GDP per capita.

These various complementary studies illustrate how a broader scope of analysis could provide evidence to inform obesity-related multisectoral intervention decisions.

Designing an intervention package

Economic analyses of single interventions are useful, but they do not in themselves provide guidance for a national strategy for obesity prevention and control. To turn the rising tide of obesity, a comprehensive assessment of an intervention package in various settings and contexts is required, including potential synergies among chosen interventions and their scalability to a subnational or national level.

Several studies provide economic analysis of an intervention package at a national level with different degrees of methodological robustness. Table 2 provides summaries of these studies (⁴²42. Cecchini M, Sassi F, Lauer JA, Lee YY, Guajardo-Barron V, Chisholm D. Tackling of unhealthy diets, physical inactivity, and obesity: health effects and cost-effectiveness. Lancet. 2010;376(9754):1775–84., ⁵⁵55. Haby M, Vos T, Carter R, Moodie M, Markwick A, Magnus A, et al. A new approach to assessing the health benefit from obesity interventions in children and adolescents: the assessing cost-effectiveness in obesity project. Int J Obes. 2006;30(10):1463.–⁶⁰60. PricewaterhouseCoopers. Weighing the cost of obesity: a case for action. Available at: https://www.pwc.com.au/pdf/weighing-the-cost-of-obesity-final.pdf Accessed 8 March 2018.
https://www.pwc.com.au/pdf/weighing-the-... ). These studies recognize that a package should include both population-level and targeted interventions. Targets usually include children, obese individuals, or populations with low socioeconomic status. Considered intervention packages include health education, regulation, fiscal measures, individual counseling, medical treatment of obesity, healthy eating, and physical activity interventions in schools and worksites. Typically, assessed interventions require significant upfront investments, but only achieve impact after several years, such that at least five years of experience is needed for them to reach an acceptable level of cost-effectiveness. Interventions with the most favorable cost-effectiveness ratio at the population level are outside health care (⁴²42. Cecchini M, Sassi F, Lauer JA, Lee YY, Guajardo-Barron V, Chisholm D. Tackling of unhealthy diets, physical inactivity, and obesity: health effects and cost-effectiveness. Lancet. 2010;376(9754):1775–84., ⁵⁵55. Haby M, Vos T, Carter R, Moodie M, Markwick A, Magnus A, et al. A new approach to assessing the health benefit from obesity interventions in children and adolescents: the assessing cost-effectiveness in obesity project. Int J Obes. 2006;30(10):1463., ⁵⁶56. Carter R, Moodie M, Markwick A, Magnus A, Vos T, Swinburn B, et al. Assessing cost-effectiveness in obesity (ACE-Obesity): an overview of the ACE approach, economic methods and cost results. BMC Public Health. 2009;9(1):419.). Individual-level interventions on their own may take decades to reach a favorable cost-effectiveness ratio due to difficulties in reaching a large proportion of the population. In contrast, interventions in the environments that shape obesogenic behaviors (e.g., food labeling) have a modest individual effect, but are societally cost-effective because a modest effect is aggregated over an entire population, and implementation costs are relatively low.

A diverse package of complementary population-level interventions in obesogenic environments offers the most promising investment scenario for most country contexts. To support this, however, more evidence of a long-term effect of population-level interventions is needed. Further, global tobacco control experience shows that comprehensiveness and synergies are crucial for effectiveness (⁶¹61. World Health Organization. WHO Framework Convention on Tobacco Control. Geneva: WHO; 2003.). However, most integrated assessments for obesity action consider an overall effect of an intervention package as a sum of individual intervention effects, without consideration of cross-effects or synergies. We found only one study (⁴²42. Cecchini M, Sassi F, Lauer JA, Lee YY, Guajardo-Barron V, Chisholm D. Tackling of unhealthy diets, physical inactivity, and obesity: health effects and cost-effectiveness. Lancet. 2010;376(9754):1775–84.) that formally modeled a synergy effect.

Even if an intervention is effective at preventing obesity at reasonable cost (cost-effectiveness), other criteria influence decision-making. As preventive interventions are aimed at having a long-lasting effect, the majority of studies in Table 2 assess sensitivity of CEA results to the sustainability of an intervention effect. Also, the CEA/CUA-based studies in Table 2 apply criteria of equity, acceptability to stakeholders, feasibility of implementation, and scalability of interventions to a national level. Formal quantitative applications exist to incorporate these criteria in economic analysis (e.g., in the ACE study (⁵⁶56. Carter R, Moodie M, Markwick A, Magnus A, Vos T, Swinburn B, et al. Assessing cost-effectiveness in obesity (ACE-Obesity): an overview of the ACE approach, economic methods and cost results. BMC Public Health. 2009;9(1):419.), a CEA was undertaken specifically for indigenous populations), or to apply afterwards. In most instances, however, when other criteria were formally considered, it was in the form of a qualitative assessment by a stakeholder committee. It is noteworthy that guidelines in areas outside health (such as with environment and public service programs) suggest clear, explicit approaches to incorporate equity into analysis (¹⁶16. National Center for Environmental Economics, Office of Policy, U.S. Environmental Protection Agency. Guidelines for preparing economic analyses 2014. Available at: https://www.epa.gov/environmental-economics/guidelines-preparing-economic-analyses Accessed 15 January 2018.
https://www.epa.gov/environmental-econom... , ⁵¹51. HM Treasury. The Green Book; appraisal and evaluation in central government. Available at: https://www.gov.uk/government/publications/the-green-book-appraisal-and-evaluation-in-central-governent Accessed 15 January 2018.
https://www.gov.uk/government/publicatio... ).

DISCUSSION

The landscape of studies concerning the investment case for obesity is dominated by CEA/CUA. Some of these analyses are broader than others in terms of the number of interventions assessed and the criteria for intervention ranking. Significant methodological differences across the studies that we reviewed (even among CUAs/CEAs) prevent a comparison of results. Thus, studies that assess a variety of interventions using the same approach are the most useful. Among CUAs that analyzed packages of intervention for national contexts, some analyses, such as Cecchini et al. (⁴²42. Cecchini M, Sassi F, Lauer JA, Lee YY, Guajardo-Barron V, Chisholm D. Tackling of unhealthy diets, physical inactivity, and obesity: health effects and cost-effectiveness. Lancet. 2010;376(9754):1775–84.) and ACE-Obesity (⁵⁶56. Carter R, Moodie M, Markwick A, Magnus A, Vos T, Swinburn B, et al. Assessing cost-effectiveness in obesity (ACE-Obesity): an overview of the ACE approach, economic methods and cost results. BMC Public Health. 2009;9(1):419.), are based on rigorous epidemiological models incorporating uncertainty. Other CUA studies, such as McKinsey Global Institute (⁵⁹59. Dobbs R, Sawers C, Thompson F, Manyika J, Woetzel J, Child P, et al. Overcoming obesity: an initial economic analysis. Available at: https://www.mckinsey.com/industries/healthcare-systems-and-services/our-insights/how-the-world-could-better-fight-obesity Accessed 15 January 2018.
https://www.mckinsey.com/industries/heal... ), rely on intervention evidence from systematic reviews or from comprehensive studies. Several LAC countries have launched comprehensive packages of antiobesity interventions (⁴4. Barquera S, Campos I, Rivera JA. Mexico attempts to tackle obesity: the process, results, push backs and future challenges. Obes Rev. 2013;14(S2):69–78., ⁶²62. Caballero B, Vorkoper S, Anand N, Rivera J. Preventing childhood obesity in Latin America: an agenda for regional research and strategic partnerships. Obes Rev. 2017;18(S2):3–6.). However, the evidence on these interventions' effectiveness is sparse, and economic analyses of the packages as a whole, including their synergetic effect, are as yet limited.

The scope of an investment case for obesity prevention and control is large, and many methodological and evidence gaps exist. Moving forward will require a concerted effort of researchers, evaluators, and surveillance experts. In the process of developing intervention and research projects, early involvement by economists and other social scientists is needed in order to collect relevant economic data and ensure rigorous economic analysis. Table 3 summarizes two things: 1) gaps in current methods and evidence that impede the development of comprehensive investment cases for obesity prevention and control and 2) ways forward (⁸8. Ellis VL, Milliken OV. Integrating economics into the rationale for multisectoral action on obesity. Rev Panam Salud Publica. 2018;42:e58. https://doi.org/10.26633/RPSP.2018.58
https://doi.org/10.26633/RPSP.2018.58... , ⁴²42. Cecchini M, Sassi F, Lauer JA, Lee YY, Guajardo-Barron V, Chisholm D. Tackling of unhealthy diets, physical inactivity, and obesity: health effects and cost-effectiveness. Lancet. 2010;376(9754):1775–84., ⁵⁶56. Carter R, Moodie M, Markwick A, Magnus A, Vos T, Swinburn B, et al. Assessing cost-effectiveness in obesity (ACE-Obesity): an overview of the ACE approach, economic methods and cost results. BMC Public Health. 2009;9(1):419., ⁶³63. Cawley J. The impact of obesity on wages. J Hum Resour. 2004;39(2):451–74.).

On the methodological side, developing applications of existing methods for the monetary valuation of benefits will be essential to gain multisectoral support for obesity prevention and control. Although we found no studies that monetized health and other benefits of a comprehensive intervention package to address obesity, valuations of benefits from reduced obesity have been attempted (⁴⁷47. Cawley J. Contingent valuation analysis of willingness to pay to reduce childhood obesity. Econ Hum Biol. 2008;6(2):281–92.–⁴⁹49. Fu T, Lin Y, Huang CL. Willingness to pay for obesity prevention. Econ Hum Biol. 2011;9(3):316–24.), and associated methods are part of government agencies' guidelines for economic analyses (¹⁶16. National Center for Environmental Economics, Office of Policy, U.S. Environmental Protection Agency. Guidelines for preparing economic analyses 2014. Available at: https://www.epa.gov/environmental-economics/guidelines-preparing-economic-analyses Accessed 15 January 2018.
https://www.epa.gov/environmental-econom... , ⁵¹51. HM Treasury. The Green Book; appraisal and evaluation in central government. Available at: https://www.gov.uk/government/publications/the-green-book-appraisal-and-evaluation-in-central-governent Accessed 15 January 2018.
https://www.gov.uk/government/publicatio... ).

The subsection above on designing an intervention package outlines criteria other than economic efficiency that are important for decision-making. Among these are equity considerations, including the impact on the most vulnerable populations; feasibility and scalability of an intervention at a population level; and acceptability to various stakeholders. Transparent and consistent approaches for integrating these considerations into an investment case are required to improve decision-making and gain multisectoral buy-in. Here, guidelines and practical applications used by other sectors could be helpful for developing approaches with broad acceptance.

On the evidence side, progress is impeded by a lack of data and data infrastructure. This is shown not only by limited economic analyses of strategies implemented to address obesity throughout the Americas, but also by a paucity of evidence on intervention effectiveness in general, and on the cost of obesity to economies within LAC in particular. Evidence needs to be expanded to include prospective and retrospective economic evaluation of intervention packages, and to incorporate the broader costs of obesity, including impacts on diverse economic actors. While there may be opportunities for researchers to better utilize existing datasets, national authorities will likely need to invest in integrating economic data into public health surveillance infrastructure or surveys, including linkage or collection of new economic data, to support evidence-based policies. In the interim, countries can learn and extrapolate from their regional neighbors and adapt successful interventions to their context.

In practice, an investment case will differ from one jurisdiction to another, based on the perspective of analysis and the data in hand. Moreover, the choice of the most effective policy suite for a specific national context will be determined by a number of factors. These include the country-specific epidemiological profile, structure of the economy, dependence on trade, evidence on market failures, and distributional issues.

Acknowledgments

This paper has been facilitated by a discussion at a thematic working group virtual meeting and comments from participants of the in-person meeting on Advancing Economics for Prevention and Control of Noncommunicable Diseases in the Americas organized by PAHO in 2016. The authors thank John Cawley, Michele Cecchini, guest editors, and anonymous referees for their valuable comments.

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