Dong Wentan, Zeng Qiang, Ma Yue, Li Guoxing, Pan Xiaochuan
Department of Occupational and Environmental Health, School of Public Health, Peking University, No. 38, Xueyuan Rd, Haidian District, Beijing 100191, China.
Tianjin Center for Disease Control and Prevention, Tianjin 300011, China.
Int J Environ Res Public Health. 2016 Sep 21;13(9):933. doi: 10.3390/ijerph13090933.
Heat waves are associated with increased mortality, however, few studies have examined the added effect of heat waves. Moreover, there is limited evidence for the influence of different heat wave definitions (HWs) on cardiovascular mortality in Beijing, the capital of China. The aim of this study was to find the best HW definitions for cardiovascular mortality, and we examined the effect modification by an individual characteristic on cardiovascular mortality in Beijing, a typical northern city in China. We applied a Poisson generalized additive approach to estimate the differences in cardiovascular mortality during heat waves (using 12 HWs) compared with non-heat-wave days in Beijing from 2006 to 2009. We also validated the model fit by checking the residuals to ensure that the autocorrelation was successfully removed. In addition, the effect modifications by individual characteristics were explored in different HWs. Our results showed that the associations between heat waves and cardiovascular mortality differed from different HWs. HWs using the 93th percentile of the daily average temperature (27.7 °C) and a duration ≥5 days had the greatest risk, with an increase of 18% (95% confidence interval (CI): 6%, 31%) in the overall population, 24% (95% CI: 10%, 39%) in an older group (ages ≥65 years), and 22% (95% CI: 3%, 44%) in a female group. The added effect of heat waves was apparent after 5 consecutive heat wave days for the overall population and the older group. Females and the elderly were at higher risk than males and younger subjects (ages <65 years). Our findings suggest that heat wave definitions play a significant role in the relationship between heat wave and cardiovascular mortality. Using a suitable definition may have implications for designing local heat early warning systems and protecting the susceptible populations during heat waves.
热浪与死亡率上升相关，然而，很少有研究探讨热浪的附加影响。此外，关于不同热浪定义（HWs）对中国首都北京心血管死亡率影响的证据有限。本研究的目的是找出针对心血管死亡率的最佳热浪定义，并且我们考察了个体特征对北京（中国一个典型的北方城市）心血管死亡率的效应修正。我们应用泊松广义相加模型方法来估计2006年至2009年北京热浪期间（使用12种热浪定义）与非热浪日相比心血管死亡率的差异。我们还通过检查残差来验证模型拟合，以确保成功消除自相关。此外，在不同的热浪定义中探讨了个体特征的效应修正。我们的结果表明，热浪与心血管死亡率之间的关联因不同的热浪定义而异。使用日平均温度第93百分位数（27.7℃）且持续时间≥5天的热浪定义具有最大风险，总体人群中增加了18%（95%置信区间（CI）：6%，31%），老年组（年龄≥65岁）中增加了24%（95%CI：10%，39%），女性组中增加了22%（95%CI：3%，44%）。对于总体人群和老年组，连续5天热浪之后热浪的附加效应明显。女性和老年人比男性和年轻受试者（年龄<65岁）面临更高风险。我们的研究结果表明，热浪定义在热浪与心血管死亡率之间的关系中起着重要作用。使用合适的定义可能对设计当地的热浪早期预警系统以及在热浪期间保护易感人群具有意义。
