Evaluating the role of fiscal policy in improving diets and preventing chronic disease in Chile: impact evaluation and modelling

慢性病（如中风、心脏病和糖尿病）——往往是由不健康的饮食造成的——在发展中国家的死亡率和发病率中所占的比例迅速上升。它们不仅是一种疾病，而且给有关国家造成了沉重的经济负担。智利正面临着一项巨大的挑战，要遏制不断上升的肥胖率和与饮食有关的疾病。在智利，这种疾病负担对穷人的影响大于对富人的影响。让更健康的选择更实惠——而不健康的选择更昂贵——似乎是解决问题的一个有希望的选择。毕竟，在长期实行税收政策的减少烟酒消费的努力中，使用价格激励已被证明非常有效。然而，当涉及到使用经济激励来促进更健康的饮食选择时，我们到目前为止几乎没有令人信服的证据来证明这种税收或补贴政策是否真的会产生预期的结果。这是因为大部分“证据”是基于对此类政策的假设建模，而不是基于对这些政策在现实世界中实施的实际案例的评估。2014年9月，智利是世界上为数不多的几个国家之一，实施了健康饮食的价格激励措施。更具体地说，智利政府增加了含糖饮料的消费税，同时减少了它认为非含糖饮料的税收。这是一个非常难得的机会，首先可以评估这项政策在相对较短的时间内（1年）是否奏效。进行这样的评估是具有挑战性的，并且需要使用产生可信影响证据的方法，即使该政策没有作为随机实验实施（如果评估新药的有效性，就会发生这种情况）。然而，在公共卫生的许多领域都是如此，有一些方法已经被应用，也可以被应用。另一个挑战是，在包括智利在内的许多国家，没有现成的适当数据来进行这种分析。然而，某些商业市场研究公司定期收集了高质量、详细的家庭购买数据，我们坚信这是目前允许我们评估政策影响的唯一数据。这些数据非常细致，提供了在智利政策生效前后的几年中，一组具有全国代表性的家庭基本上所有带回家购买饮料的信息。一旦我们评估了政策是否“有效”，就减少不健康饮料的购买而言，我们还想知道这种短期效果是否会转化为有意义的长期健康影响。这只能通过长期结果的复杂建模来完成，并且团队拥有开发此类模型的专业知识和跟踪记录。此外，智利政府热衷于探讨进一步完善这一政策。为了直接为这种审议提供信息，我们将使用我们的模型来分析一系列相关的税收或补贴政策，这些政策同样旨在促进更健康的饮食，至少在现有证据的基础上，这些政策看起来很有希望。我们已经与卫生部的高级决策者建立了一个适当的双向沟通渠道，这将有助于确保我们提供的证据能够满足政府的知识需求，而不会过度干扰研究。总的来说，这项研究不仅将为智利政府提供重要的证据，而且还将为许多其他低收入和中等收入国家提供重要的证据，这些国家也面临着饮食相关疾病的挑战，并渴望了解财政政策在促进健康饮食和预防慢性病方面的实际范围。

Chronic diseases (e.g. stroke, heart diseases, and diabetes) - often driven by unhealthy diets - account for a fast growing share of mortality and morbidity in developing countries. They impose not only a disease but also a substantial economic burden to the countries concerned. Chile is facing an enormous challenge to curb rising rates of obesity and diet-related ill-health. Much of this disease burden is affecting the poor more than the rich within Chile.Making healthier choices more affordable - and unhealthier options more expensive - might appear as a promising option to tackle the problem. After all, using price incentives has been shown to work very effectively in the efforts to reduce tobacco and alcohol consumption, where tax policies have long been applied. Yet when it comes to using economic incentives to promote healthier diet choices, we are so far left with preciously little, convincing evidence on whether such tax or subsidy policies would in fact have the desired results. This is because the bulk of the "evidence" is based on hypothetical modelling of such policies, rather than on the evaluation of actual examples of cases where they have been implemented in the real world. Chile is one out of a handful of countries world-wide that have now - in September 2014 - implemented a price incentive for healthier diets. More specifically, the Chilean Government has increased the excise tax on sugar sweetened beverages (SSBs), while reducing the tax on what it considers as non-SSBs. This is a great and extremely rare opportunity to first of all evaluate whether this policy has worked over a comparatively short period of time (1 year).Conducting such an evaluation is challenging and requires the use of methods that produce credible impact evidence, even though the policy has not been implemented as a randomised experiment (which is what would have happened if evaluating the effectiveness of a new drug). This is the case in many areas of public health, however, and there are methods out there that have been, and can be, applied. The other challenge is that suitable data is not readily at hand in many countries, including in Chile, to conduct such an analysis. There is, however, high quality, detailed household purchasing data routinely collected by certain commercial market research companies, and we strongly believe this is the only data that currently allows us to assess the policy impact. Such data is exceptionally fine-grained, providing information on essentially all take-home purchases of beverages made by a nationally representative set of households over several years before and after the Chilean policy entered into force.Once we have evaluated whether the policy has 'worked', in terms of reducing unhealthy beverage purchasing, we then also want to know whether this short term effect translates into meaningful longer term health effects. This can only be done via complex modelling of the longer term consequences, and the team has the expertise and track record to develop such models. In addition, the Chilean Government is keen to explore further refinements to this policy. In order to directly inform such deliberations, we will use our model to also analyse a range of related tax or subsidy policies, again aimed at promoting healthier diets, which appear at least promising on the basis of existing evidence. We have established a suitable, two-way communication channel with the senior policymakers in the Ministry of Health that will help ensure that the kind of evidence we produce will answer to the knowledge needs of the Government, without unduly interfering with the research. Overall, this research will contribute vital evidence not only to the Chilean government but also to many other low- and middle-income countries also facing the challenge of diet-related ill health and eager to understand the actual scope for fiscal policies in the promotion of healthier diets and the prevention of chronic diseases.