Luo Kai, Li Runkui, Wang Zongshuang, Zhang Ruiming, Xu Qun
Department of Epidemiology and Biostatistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing 100005, China; Center of Environmental and Health Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100005, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science, Beijing 100101, China.
Environ Pollut. 2017 Nov;230:989-999. doi: 10.1016/j.envpol.2017.07.045. Epub 2017 Jul 25.
There is limited evidence showing the mortality effects of temperature variability (TV) on cardiovascular diseases. The joint effects between TV and air pollutants are also less well-established. This study aims to assess the effect modification of TV-cardiovascular mortality by air pollutants in three Chinese cities (Beijing, Nanjing and Chengdu). Data of daily mortality, air pollutants and meteorological factors from 2008 to 2011 was collected from each city. TV was calculated as the standard deviation of daily maximum and minimum temperatures over exposure days. The city-specific effect estimates of TV on cardiovascular mortality were calculated using a quasi-Poisson regression model, adjusting for potential confounders (e.g., seasonality and temperature). An interaction term of TV and a three-level air pollutants stratum indicator was included in the models. Effect modifications by air pollutants were assessed by comparing the estimates of TV's effect between pollutant stratums and calculating the corresponding 95% confidential interval of the differences. Multivariate meta-analysis was conducted to obtain the pooled estimates. The data showed that TV was associated with increased risk of cardiovascular mortality, especially for longer TV exposure days (0-8 days, TV08). This association was still observed after adjusting for air pollutants on current day or the previous two days. Stronger estimates were observed in females, but no significant difference between males and females was detected, indicating the absence of evidence of effect modification by gender. Estimates of TV-cardiovascular mortality varied across two season periods (warm and cool season) and age groups, but the evidence of effect modification by age and seasons was absent. Regarding the effect modification of TV-cardiovascular mortality association by air pollutants, a significant effect modification was identified for PM but not for NO and SO in the whole population for all TV exposure days. This finding also persisted in subgroups, specifically in females and the elderly.
仅有有限的证据表明温度变异性（TV）对心血管疾病死亡率的影响。TV与空气污染物之间的联合效应也尚未得到充分证实。本研究旨在评估中国三个城市（北京、南京和成都）中空气污染物对TV与心血管疾病死亡率之间关系的效应修正作用。收集了每个城市2008年至2011年的每日死亡率、空气污染物和气象因素数据。TV通过暴露天数内每日最高和最低温度的标准差来计算。使用准泊松回归模型计算TV对心血管疾病死亡率的特定城市效应估计值，并对潜在混杂因素（如季节性和温度）进行调整。模型中纳入了TV与一个三级空气污染物分层指标的交互项。通过比较污染物分层之间TV效应的估计值并计算相应差异的95%置信区间，评估空气污染物的效应修正作用。进行多变量荟萃分析以获得合并估计值。数据表明，TV与心血管疾病死亡率风险增加相关，尤其是对于较长的TV暴露天数（0 - 8天，TV08）。在对当日或前两天的空气污染物进行调整后，这种关联仍然存在。在女性中观察到更强的估计值，但未检测到男性和女性之间的显著差异，表明没有证据表明存在性别效应修正。TV与心血管疾病死亡率的估计值在两个季节期（温暖季节和凉爽季节）和年龄组之间有所不同，但没有年龄和季节效应修正的证据。关于空气污染物对TV与心血管疾病死亡率关联的效应修正作用，在所有TV暴露天数的总体人群中，确定了PM有显著的效应修正作用，而NO和SO则没有。这一发现也在亚组中持续存在，特别是在女性和老年人中。
