Background Heat waves have devastating health effects on human populations. Our previous study shows that heat waves had a higher risk for stroke mortality in Nanjing. Despite many studies of mortality risk for heat waves in urban areas, few studies have examined the spatial variations among different regions. Objectives We analyzed the stroke mortality of a heat wave in 2010 in Nanjing, China and investigated the spatial variability of stroke mortality risk between heat wave days and non-heat wave days. Methods Within each town of Nanjing, we calculated the stroke mortality during the heat wave (July 30-August 22, 2010) and a reference period (July 30-August 22, 2009). We estimated the rate ratios (RRs) of urban, suburban, and rural regions. Spatial autocorrelation was used to measure the spatial patterns of heat wave mortality. The Anselin Local Moran's I statistic was applied to identify the statistically significant spatial clusters. Results Stroke mortality in both the heat wave and the reference period were spatially clustered, with the Moran's Index of 0.147 and 0.089. During the reference period, two HH spots(areas with high stroke mortality surrounded by other areas with high stroke mortality) were found in rural regions and the clusters in urban and suburban regions were not significant. During the heat wave, the two hot spots in rural regions remained while an HL spot (areas with high mortality surrounded by other areas with low mortality) was discovered in the suburban region. During the heat wave, the RRs of stroke mortality were 2.25(95%CI,1.03-4.27) in the urban area, 4.14(95%CI,2.77-5.95) in the suburban area, and 1.66(95%CI,1.33-2.05) in the rural area. Conclusions We found that stroke mortality risk from heat waves in Nanjing has clear spatial patterns. During the heat wave, suburban regions have the highest and spatially clustered stroke mortality risk. These findings revealed the importance of the health impact of heat waves in suburban areas.
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机译：背景技术热浪对人类的健康具有毁灭性的影响。我们以前的研究表明，南京的热浪中风死亡率更高。尽管对城市热浪的死亡风险进行了许多研究，但很少有研究研究了不同地区之间的空间变化。目的我们分析了中国南京市2010年热浪的卒中死亡率，并调查了热浪天和非热浪天之间的中风死亡率风险的空间变异性。方法我们计算了南京市每个镇的热浪期间（2010年7月30日至8月22日）和参考期（2009年7月30日至8月22日）的卒中死亡率。我们估计了城市，郊区和农村地区的比率（RRs）。使用空间自相关来测量热波死亡率的空间格局。应用Anselin Local Moran's I统计量来识别具有统计意义的空间聚类。结果热浪和参考期的卒中死亡率在空间上均呈聚类，Moran指数分别为0.147和0.089。在参考期内，在农村地区发现了两个高发区（高卒中死亡率地区，其他地区为高卒中死亡率地区），城市和郊区的聚类不明显。在热浪期间，农村地区仍然存在两个热点，而郊区则发现了HL点（高死亡率地区，其他低死亡率地区）。在热浪期间，城市地区卒中死亡率的RRs为2.25（95％CI，2.73-4.95），郊区为4.14（95％CI，2.77-5.95），而1.66（95％CI，1.33-1.33） 2.05）。结论我们发现南京热浪导致的中风死亡风险具有清晰的空间格局。在热浪期间，郊区地区的卒中死亡风险最高且在空间上呈簇状分布。这些发现揭示了郊区热浪对健康的影响的重要性。
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