Temperature, temperature extremes, and mortality:: a study of acclimatisation and effect modification in 50 US cities
Temperature, temperature extremes, and mortality:: a study of acclimatisation and effect modification in 50 US cities
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DOI：
10.1136/oem.2007.033175
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发表时间：
2007-12-01
影响因子：
4.9
通讯作者：
Schwartz, J.
中科院分区：
文献类型：
--
作者：
Medina-Ramon, M.;Schwartz, J.
目的：研究不同地区冷热温度对死亡率的影响，影响效应估计的变异性的决定因素及其对适应的影响。方法：作者在美国50个城市进行了一项交叉病例研究。他们使用了-2000年期间6513330例死亡的每日死亡率和天气数据。暴露使用两种方法进行评估。首先，作者根据当地的温度分布，使用特定城市的指标变量来确定暴露在极端温度下的情况。其次，他们使用分段线性变量来评估高于或低于阈值的连续范围内的温度暴露。在特定季节的模型中考察了冷热温度的影响。结果：发现与极端寒冷(两天累计增加1.59%(95%可信区间0.56至2.63))和极端高温(5.74%(95%可信区间3.38至8.15))有关的死亡率增加，前者尤其易发生心肌梗死和心脏骤停死亡。在温度不那么极端的情况下，死亡率的增加不那么明显。极端寒冷(定义为百分位数)的影响在不同气候的城市中是一致的，这表明只有寒冷温度的不寻常(而不是其绝对值)对死亡率(即适应寒冷)有实质性影响。相反，热效应是非常不同的，在夏季较温和、空调较少和人口密度较高的城市观察到的影响最大。对臭氧进行调整后得到了类似的结果，但由于其他未受控制的污染物，可能存在一些残留的混杂。结论：作者在大样本城市中证实，寒冷和炎热的温度都会增加死亡风险。这些发现表明，全球变暖导致的与高温有关的死亡率的增加不太可能通过与寒冷有关的死亡率的下降来弥补，而且人们对高温的适应仍然不完全。
Objectives: The authors examined the increase in mortality associated with hot and cold temperature in different locations, the determinants of the variability in effect estimates, and its implications for adaptation.Methods: The authors conducted a case-crossover study in 50 US cities. They used daily mortality and weather data for 6 513 330 deaths occurring during 1989 -2000. Exposure was assessed using two approaches. First, the authors determined exposure to extreme temperatures using city-specific indicator variables based on the local temperature distribution. Secondly, they used piecewise linear variables to assess exposure to temperature on a continuous scale above/ below a threshold. Effects of hot and cold temperature were examined in season-specific models. In a meta-analysis of the city-specific results, the authors examined several city characteristics as effect modifiers.Results: Mortality increases associated with both extreme cold (2-day cumulative increase 1.59% (95% CI 0.56 to 2.63)) and extreme heat (5.74% (95% CI 3.38 to 8.15)) were found, the former being especially marked for myocardial infarction and cardiac arrest deaths. The increase in mortality was less marked at less extreme temperatures. The effect of extreme cold (defined as a percentile) was homogeneous across cities with different climates, suggesting that only the unusualness of the cold temperature (and not its absolute value) had a substantial impact on mortality (that is, acclimatisation to cold). Conversely, heat effects were quite heterogeneous, with the largest effects observed in cities with milder summers, less air conditioning and higher population density. Adjustment for ozone led to similar results, but some residual confounding could be present due to other uncontrolled pollutants.Conclusions: The authors confirmed in a large sample of cities that both cold and hot temperatures increase mortality risk. These findings suggest that increases in heat-related mortality due to global warming are unlikely to be compensated for by decreases in cold-related mortality and that population acclimatisation to heat is still incomplete.