What is cold-related mortality? A multi-disciplinary perspective to inform climate change impact assessments
What is cold-related mortality? A multi-disciplinary perspective to inform climate change impact assessments
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DOI：
10.1016/j.envint.2018.08.053
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发表时间：
2018-12-01
影响因子：
11.8
通讯作者：
Vardoulakis, Sotiris
中科院分区：
文献类型：
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作者：
Arbuthnott, Katherine;Hajat, Shakoor;Vardoulakis, Sotiris
背景：关于炎热和寒冷天气的死亡负担以及气候变化可能如何改变这些之间的平衡的讨论越来越多。气候变化的净影响经常被提出，在某些情况下，这些可能表明与寒冷相关的死亡率的降低将超过与炎热相关的死亡率的增加。然而，这些讨论的关键是，与温度相关的死亡率的大小对温度阈值的设置完全敏感，高于或低于该温度阈值将影响建模。特别是对于冷暴露，阈值效应通常不明确，已发表的研究之间阈值放置的选择差异很大，即使在同一地点也是如此。尽管如此，关于适当阈值选择以及报告的关联是否反映真正的因果关系的讨论很少，即是否所有发生在给定温度阈值以下的死亡都可以被视为与寒冷相关，因此可能会随着气候变暖而减少。 目标：我们的目标是围绕阈值设置的重要性发起讨论，并检查用于量化与寒冷相关的死亡率的整个温度范围内因果关系的证据。我们研究了解因果机制是否可以为阈值选择、当前和未来与寒冷相关的健康负担的解释及其在政策制定中的使用提供信息。方法：以大伦敦数据为例，我们首先说明与寒冷相关的死亡率对阈值选择的敏感性。然后，我们以布拉德福德希尔标准为框架，整合来自多个学科和领域的知识和证据，包括动物和人类生理学、流行病学、生物标志物研究和人群水平研究。这允许讨论在健康影响研究中使用的“寒冷”温度和滞后期范围内运行的几种可能的直接和间接因果机制，以及这是否反过来可以为适当的阈值设置提供信息。结果：来自一系列学科的证据似乎支持寒冷在一系列温度和滞后期之间存在因果关系，尽管有更一致的证据表明在更极端的温度下存在因果关系。寒冷死亡的“直接”机制可能发生在较低的温度下，而“间接”机制（例如通过增加感染传播）可能发生在较温和的温度下，这似乎是合理的。结论：区分“极度”和“中度”寒冷（例如英国大约 8-9 摄氏度到 18 摄氏度之间的温度）的影响可能有助于解释引用归因死亡率的研究 负担。然而，仍然存在一个普遍的困境：是否使用较低的寒冷阈值更好，低于该阈值我们可以更确定因果关系，但存在低估寒冷死亡人数的风险。
Background: There is a growing discussion regarding the mortality burdens of hot and cold weather and how the balance between these may alter as a result of climate change. Net effects of climate change are often presented, and in some settings these may suggest that reductions in cold-related mortality will outweigh increases in heat related mortality. However, key to these discussions is that the magnitude of temperature-related mortality is wholly sensitive to the placement of the temperature threshold above or below which effects are modelled. For cold exposure especially, where threshold effects are often ill-defined, choices in threshold placement have varied widely between published studies, even within the same location. Despite this, there is little discussion around appropriate threshold selection and whether reported associations reflect true causal relationships - i.e. whether all deaths occurring below a given temperature threshold can be regarded as cold-related and are therefore likely to decrease as climate warms.Objectives: Our objectives are to initiate a discussion around the importance of threshold placement and examine evidence for causality across the full range of temperatures used to quantify cold-related mortality. We examine whether understanding causal mechanisms can inform threshold selection, the interpretation of current and future cold-related health burdens and their use in policy formation.Methods: Using Greater London data as an example, we first illustrate the sensitivity of cold related mortality to threshold selection. Using the Bradford Hill criteria as a framework, we then integrate knowledge and evidence from multiple disciplines and areas-including animal and human physiology, epidemiology, biomarker studies and population level studies. This allows for discussion of several possible direct and indirect causal mechanisms operating across the range of 'cold' temperatures and lag periods used in health impact studies, and whether this in turn can inform appropriate threshold placement.Results: Evidence from a range of disciplines appears to support a causal relationship for cold across a range of temperatures and lag periods, although there is more consistent evidence for a causal effect at more extreme temperatures. It is plausible that 'direct' mechanisms for cold mortality are likely to occur at lower temperatures and 'indirect' mechanisms (e.g. via increased spread of infection) may occur at milder temperatures.Conclusions: Separating the effects of 'extreme' and 'moderate' cold (e.g. temperatures between approximately 8-9 degrees C and 18 degrees C in the UK) could help the interpretation of studies quoting attributable mortality burdens. However there remains the general dilemma of whether it is better to use a lower cold threshold below which we are more certain of a causal relationship, but at the risk of under-estimating deaths attributable to cold.