London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
J Epidemiol Community Health. 2011 Apr;65(4):340-5. doi: 10.1136/jech.2009.093161. Epub 2010 May 3.
It is well known that high ambient temperatures are associated with increased mortality, even in temperate climates, but some important details are unclear. In particular, how heat-mortality associations (for example, slopes and thresholds) vary by climate has previously been considered only qualitatively.
An ecological time-series regression analysis of daily counts of all-cause mortality and ambient temperature in summers between 1993 and 2006 in the 10 government regions was carried out, focusing on all-cause mortality and 2-day mean temperature (lags 0 and 1).
All regions showed evidence of increased risk on the hottest days, but the specifics, in particular the threshold temperature at which adverse effects started, varied. Thresholds were at about the same centile temperatures (the 93rd, year-round) in all regions-hotter climates had higher threshold temperatures. Mean supra-threshold slope was 2.1%/°C (95% CI 1.6 to 2.6), but regions with higher summer temperatures showed greater slopes, a pattern well characterised by a linear model with mean summer temperature. These climate-based linear-threshold models capture most, but not all, the association; there was evidence for some non-linearity above thresholds, with slope increasing at highest temperatures.
Effects of high daily summer temperatures on mortality in English regions are quite well approximated by threshold-linear models that can be predicted from the region's climate (93rd centile and mean summer temperature). It remains to be seen whether similar relationships fit other countries and climates or change over time, such as with climate change.
众所周知，即使在温带气候下，环境温度升高也与死亡率增加有关，但一些重要细节尚不清楚。特别是，热死亡率关联（例如，斜率和阈值）如何因气候而异，此前仅从定性角度进行了考虑。
对 1993 年至 2006 年夏季 10 个政府区域内所有原因死亡率和环境温度的每日计数进行了生态时间序列回归分析，重点关注所有原因死亡率和 2 天平均温度（滞后 0 和 1）。
所有区域都有在最热日出现风险增加的证据，但具体情况，特别是开始出现不利影响的阈值温度，存在差异。阈值在所有区域中大致相同的百分位数温度（全年第 93 位），较热的气候具有更高的阈值温度。高于阈值的平均超阈值斜率为 2.1%/°C（95%CI 1.6 至 2.6），但夏季温度较高的区域斜率更大，这种模式很好地用平均夏季温度的线性模型来描述。这些基于气候的线性阈值模型可以捕捉到大部分（但不是全部）关联；在最高温度处存在超过阈值的非线性证据，斜率随着温度升高而增加。
英国各区域夏季每日高温对死亡率的影响可以通过阈值线性模型很好地近似，这些模型可以从区域气候（第 93 百分位数和平均夏季温度）来预测。其他国家和气候是否存在类似的关系，或者随着时间的推移（例如气候变化）是否会发生变化，还有待观察。
