Background

Diurnal temperature range (DTR) reflects within-day temperature variability and is closely associated with climate change. In comparison to temperature extremes, up-to-date DTR-health evidence at the regional and national scales has been still very limited worldwide, especially in Europe.

Objectives

This study aimed to provide nationwide estimates for DTR-associated effects on mortality, and explore whether season and regional-level characteristics modify DTR-mortality relation in United Kingdom.

Methods

Fourteen-year time-series data on weather and mortality were collected from 10 regions in England and Wales during 1993–2006, including 7,573,716 total deaths. A quasi-Poisson regression incorporated with distributed lag non-linear model was first applied to estimate region-specific DTR-mortality relationships. Then, a multivariate meta-analysis was employed to derive the pooled DTR effects at the national level. Also, the modifying effects of some regional characteristics (e.g., geographical and climatological) were examined by conducting multivariate meta-regression.

Results

A non-linear DTR-mortality relationship was identified in UK. At the national level, increasing DTR raised the mortality risk observably when DTR exposure was below 25th percentile or above 90th percentile of DTR distribution, with an intermediate risk plateau indicating no associations. Extremely high DTR exhibited greater adverse effect estimates in hot season compared with in cold and transitional season, whereas entirely different association patterns were observed for the season-specific effects of extremely low DTR. In addition to season, regional latitudes, average temperature and humidity were also found to significantly modify DTR-mortality relationship.

Conclusions

Our study added strong evidence that extremely high DTR increased short-term mortality, whereas the effects of extremely low DTR exhibited entirely different seasonal patterns. Also, mortality vulnerability to DTR extremes varied greatly by regional latitudes and climate conditions.

中文翻译：

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英格兰和威尔士昼间温度范围与每日死亡率的关联：一项全国性的时间序列研究

背景

昼夜温度范围（DTR）反映了一天之内的温度变化，并且与气候变化密切相关。与极端温度相比，在全球范围内，尤其是在欧洲，区域和国家范围内最新的DTR-Health证据仍然非常有限。

目标

这项研究旨在为全国范围内与DTR相关的死亡率影响提供估计，并探讨季节和区域性特征是否会改变英国的DTR死亡率关系。

方法

在1993年至2006年期间，从英格兰和威尔士的10个地区收集了有关天气和死亡率的14年时间序列数据，包括7,573,716人的总死亡人数。首先，将带有分布式滞后非线性模型的准Poisson回归应用于估计特定于区域的DTR死亡率关系。然后，进行了多元荟萃分析，以推导国家层面上汇集的DTR效应。此外，通过进行多元荟萃回归，研究了某些区域特征（例如地理和气候）的改良作用。

结果

在英国确定了非线性DTR死亡率关系。在国家一级，当DTR暴露低于DTR分布的25％或高于90％时，DTR的增加明显增加了死亡风险，中等风险水平表明没有相关性。与寒冷和过渡季节相比，极高的DTR在炎热季节表现出更大的不利影响估计，而对于极低DTR的特定季节效应，观察到完全不同的关联模式。除季节外，还发现区域纬度，平均温度和湿度显着改变了DTR死亡率关系。

结论

我们的研究增加了有力的证据，表明极高的DTR增加了短期死亡率，而极低的DTR则表现出完全不同的季节性模式。此外，因地区纬度和气候条件而对DTR极端事件造成的死亡率脆弱性差异很大。