Association between Weather-Related Factors and Cardiac Arrest of Presumed Cardiac Etiology: A Prospective Observational Study Based on Out-of-Hospital Care Data

<b>Objective</b>: The objective of this study was to determine the association between weather-related factors and out-of-hospital cardiac arrest (OHCA) of presumed cardiac etiology. <b>Methods</b>: This was a prospective observational study performed in a prehospital setting. Data from the Emergency Medical Service in Hamburg (Germany) and data from the local weather station were evaluated over a 5-year period. Weather data (temperature, humidity, air pressure, wind speed) were obtained every minute and matched with the associated rescue mission data. Lowess-Regression analysis was performed to assess the relationship between the above-mentioned weather-related factors and OHCA of presumed cardiac etiology. Additionally, varying measuring-ranges were defined for each weather-related factor in order to compare them with each other with regard to the probability of occurrence of OHCA. <b>Results</b>: During the observation period 1,558 OHCA with presumed cardiac etiology were registered (age: 67 ± 19 yrs; 62% male; hospital admission: 37%; survival to hospital discharge: 6.7%). Compared to moderate temperatures (5 – 25°C), probability of OHCA-occurrence increased significantly at temperatures above 25°C (p = 0.028) and below 5°C p = 0.011). Regarding air humidity, probability of OHCA-occurrence increased below a threshold-value of 75% compared to values above this cut-off (p = 0.006). Decreased probability was seen at moderate atmospheric pressure (1000 hPa – 1020 hPa), whereas increased probability was seen above 1020 hPa (p = 0.023) and below 1000 hPa (p = 0.035). Probability of OHCA-occurrence increased continuously with increasing wind speed (p &lt; 0.001). <b>Conclusions</b>: There are associations between several weather-related factors such as temperature, humidity, air pressure, and wind speed, and occurrence of OHCA of presumed cardiac etiology. Particularly dangerous seem to be cold weather, dry air and strong wind.

研究目的：本研究旨在明确气象相关因素与推测为心源性病因的院外心脏骤停（out-of-hospital cardiac arrest, OHCA）之间的关联。
研究方法：本研究为一项院前场景下的前瞻性观察性研究。本研究对德国汉堡紧急医疗服务（Emergency Medical Service）及当地气象站的5年时间段数据进行了分析。气象数据（气温、湿度、气压、风速）以每分钟1次的频率采集，并与对应急救任务数据进行匹配。本研究采用局部加权回归散点平滑（Lowess-Regression）分析，以评估上述气象因子与推测为心源性病因的院外心脏骤停之间的关联。此外，本研究为各气象因子设定了不同的测量区间，以对比不同区间内院外心脏骤停的发生概率。
研究结果：观测期内共登记1558例推测为心源性病因的院外心脏骤停病例，患者平均年龄为67±19岁，男性占比62%，入院率为37%，出院存活率为6.7%。与中等温度区间（5~25℃）相比，温度高于25℃（p=0.028）或低于5℃（p=0.011）时，院外心脏骤停的发生概率均显著升高。就空气湿度而言，与湿度高于75%的区间相比，湿度低于该阈值时院外心脏骤停的发生概率升高（p=0.006）。中等气压区间（1000~1020百帕）对应的院外心脏骤停发生概率较低，而气压高于1020百帕（p=0.023）或低于1000百帕（p=0.035）时，发生概率则升高。院外心脏骤停的发生概率随风速升高持续升高（p<0.001）。
研究结论：多项气象相关因子（包括气温、湿度、气压及风速）与推测为心源性病因的院外心脏骤停的发生存在相关性。其中寒冷天气、低湿度空气与强风速似乎具有较高的危险性。