Department of Preventive Medicine, School of Health Sciences, Wuhan University, 185 Donghu Road, Wuhan 430071, China.
School of Public Health and Management, Hubei University of Medicine, Shiyan 442000, China.
Environ Int. 2018 Jun;115:325-333. doi: 10.1016/j.envint.2018.03.036. Epub 2018 Apr 5.
Sudden temperature change may elevate short-term mortality and remains an important global health threat in the context of climate change. To date, however, little available temperature-mortality evidence has taken into account both intra- and inter-day temperature variability (TV), thus largely limiting the comprehensive understanding of mortality burden due to unstable weather. Moreover, seasonal and temporal patterns in TV-mortality associations were sparsely discussed, nationally and regionally.
We aimed to assess the nationwide association of all-cause mortality with hourly temperature variability (HTV), quantify HTV-attributable mortality, and further explore the temporal and seasonal variations of mortality burden due to HTV in United Kingdom.
Fourteen-year time-series data on temperature and mortality were collected from 10 regions in England and Wales during 1993-2006, totally including 7,573,716 all-cause deaths. HTV was calculated from the standard deviation of hourly temperature records within two neighboring days. A three-stage analytic approach was adopted to assess HTV-associated mortality burden. We first applied a time-series quasi-Poisson regression to estimate region-specific HTV-mortality associations, then pooled these associations at the national level using a multivariate meta-analysis, and finally estimated the HTV-attributable mortality fraction and illustrated its seasonal and temporal variations by conducting season- and period-specific analyses based on time-varying distributed lag models.
We found strong evidence that large HTV exposure elevated short-term mortality risk in England and Wales, with a pooled estimate of 1.13% (95% confidence interval (CI): 0.88, 1.39) associated with a 1-°C increase in HTV. During the whole study period, HTV accounted for a national average attributable fraction of 2.52% (95% empirical confidence interval (eCI): 2.27, 2.76) of the total deaths. This HTV-attributable mortality estimate showed a significant temporal decrease (p < 0.001) from 2.72% (95% eCI: 2.58, 2.87) in 1993-99 to 2.28% (95% eCI: 2.13, 2.43) in 2000-06. Additionally, clear seasonal variations were observed for HTV-attributable mortality burden, with the largest estimate of 3.08% (95% eCI: 2.80, 3.38) in summer, followed by 2.71% (95% eCI: 2.44, 2.98) in spring, 2.40% (95% eCI: 2.16, 2.63) in autumn, and 2.00% (95% eCI: 1.81, 2.20) in winter.
Despite clear evidence observed for the reduction, mortality burden caused by temperature variability remained a great public health threat, especially in warm seasons. It highlighted the importance of specific interventions targeted to unstable weather as well as temperature extremes, so as to reduce climate-related mortality burden.
气温骤变可能会增加短期死亡率，并且在气候变化的背景下仍然是一个重要的全球健康威胁。然而，迄今为止，很少有关于温度与死亡率关系的可用证据同时考虑到日内和日间温度变化（TV），因此在很大程度上限制了对不稳定天气导致的死亡率负担的全面了解。此外，关于 TV 与死亡率之间的季节性和时间性关联的讨论也很少在全国和地区范围内进行。
我们旨在评估全因死亡率与小时温度变化（HTV）之间的全国性关联，量化 HTV 导致的死亡率，并进一步探讨英国因 HTV 导致的死亡率负担的季节性和时间性变化。
我们收集了英格兰和威尔士 10 个地区 1993-2006 年间的 14 年时间序列温度和死亡率数据，共包括 7573716 例全因死亡。HTV 是通过两天相邻小时温度记录的标准差计算得出的。我们采用三阶段分析方法评估 HTV 相关的死亡率负担。我们首先应用时间序列准泊松回归来估计特定地区的 HTV-死亡率关系，然后通过多元荟萃分析在全国范围内汇总这些关系，最后通过基于时变分布滞后模型的季节和时段特异性分析来估计 HTV 归因死亡率比例，并说明其季节性和时间性变化。
我们发现大量证据表明，较大的 HTV 暴露会增加英格兰和威尔士的短期死亡率风险，与 HTV 增加 1°C 相关的汇总估计值为 1.13%（95%置信区间（CI）：0.88，1.39）。在整个研究期间，HTV 占全国总死亡人数的平均归因分数为 2.52%（95%经验置信区间（eCI）：2.27，2.76）。HTV 归因死亡率的这一估计值显示出显著的时间下降（p<0.001），从 1993-99 年的 2.72%（95% eCI：2.58，2.87）降至 2000-06 年的 2.28%（95% eCI：2.13，2.43）。此外，HTV 归因死亡率负担也呈现出明显的季节性变化，夏季最大估计值为 3.08%（95% eCI：2.80，3.38），其次是春季 2.71%（95% eCI：2.44，2.98）、秋季 2.40%（95% eCI：2.16，2.63）和冬季 2.00%（95% eCI：1.81，2.20）。
尽管观察到明显的减少证据，但由温度变化引起的死亡率负担仍然是一个巨大的公共卫生威胁，尤其是在温暖季节。这突出了针对不稳定天气和极端温度的具体干预措施的重要性，以减少与气候相关的死亡率负担。
