Department of Public Health and Clinical Medicine, Epidemiology and Global Health, Umeå University, Umeå, Sweden.
Environ Health. 2012 Apr 10;11:23. doi: 10.1186/1476-069X-11-23.
We examine the effect of heat waves on mortality, over and above what would be predicted on the basis of temperature alone.
Present modeling approaches may not fully capture extra effects relating to heat wave duration, possibly because the mechanisms of action and the population at risk are different under more extreme conditions. Modeling such extra effects can be achieved using the commonly left-out effect-modification between the lags of temperature in distributed lag models.
Using data from Stockholm, Sweden, and a variety of modeling approaches, we found that heat wave effects amount to a stable and statistically significant 8.1-11.6% increase in excess deaths per heat wave day. The effects explicitly relating to heat wave duration (2.0-3.9% excess deaths per day) were more sensitive to the degrees of freedom allowed for in the overall temperature-mortality relationship. However, allowing for a very large number of degrees of freedom indicated over-fitting the overall temperature-mortality relationship.
Modeling additional heat wave effects, e.g. between lag effect-modification, can give a better description of the effects from extreme temperatures, particularly in the non-elderly population. We speculate that it is biologically plausible to differentiate effects from heat and heat wave duration.
我们研究了热浪对死亡率的影响，这种影响超出了仅根据温度预测的范围。
目前的建模方法可能无法完全捕捉到与热浪持续时间有关的额外影响，这可能是因为在更极端的条件下，作用机制和风险人群不同。可以使用分布式滞后模型中温度滞后之间常见的效应修正来实现对这种额外效应的建模。
使用来自瑞典斯德哥尔摩的数据和各种建模方法，我们发现，热浪对超额死亡人数的影响稳定且具有统计学意义，每出现一个热浪日，超额死亡人数增加 8.1%至 11.6%。与热浪持续时间直接相关的影响（每天增加 2.0%至 3.9%的超额死亡人数）对整体温度-死亡率关系中允许的自由度更为敏感。然而，允许大量自由度表明过度拟合了整体温度-死亡率关系。
对额外的热浪效应进行建模，例如滞后效应修正之间的建模，可以更好地描述极端温度的影响，特别是在非老年人群体中。我们推测，区分热量和热浪持续时间的影响在生物学上是合理的。
