热浪与非意外死亡和呼吸系统疾病死亡的病例交叉研究

Relationship between Heat Waves and Daily Death from Non-accidental Death and Respiratory Disease:a Case-crossover Study

目的探讨北京市热浪对当地居民每日非意外死亡及呼吸系统疾病死亡人数的影响。方法运用病例交叉设计的基本方法,分析北京市1999年1月1日—2000年6月30日期间5次热浪对居民每日非意外死亡和呼吸系统疾病死亡人数的影响,同时研究其对慢性阻塞性肺病(COPD)死亡的影响。采用1∶1单向回顾性对照,选择死亡发生前第7天作为自身对照,分别计算不同长度的危险期时的OR值,以最高的OR值及其对应的危险期来反映每次热浪过程对每日非意外死亡及呼吸系统疾病死亡人数的影响、滞后天数及持续时间。结果研究期间共发生5次热浪。第1次持续9d,最高气温为38.8℃,平均湿度为46.7%,居民每日非意外死亡、呼吸系统疾病死亡和COPD死亡的OR值分别为1.442(95%CI:1.310～1.588),2.667(95%CI:1.893～3.756)和1.778(95%CI:1.182～2.674);第2次热浪持续3d,最高气温为36.8℃,平均湿度为61.0%,3种死因每日死亡的OR值分别为1.200(95%CI:0.973～1.480),3.000(95%CI:1.090～8.254)和3.333(95%CI:0.917～12.112);第3次热浪持续7d,最高气温为41.5℃,平均湿度为58.5%,3种死因每日死亡的OR值分别为2.135(95%CI:1.925～2.368),3.360(95%CI:2.450～4.608)和2.897(95%CI:1.899～4.418);第4次持续3d,最高气温为39.6℃,平均湿度为31.9%,3种死因每日死亡的OR值分别为1.464(95%CI:1.042～2.057),1.000(95%CI:0.375～2.664)和1.000(95%CI:0.290～3.454);第5次热浪持续4d,最高气温为37.4℃,平均湿度为42.0%,3种死因每日死亡OR值分别为和1.525(95%CI:1.099～2.118),2.000(95%CI:0.500～7.997)和2.000(95%CI:0.603～5.371)。结论热浪对居民死亡有影响,且存在滞后效应,非意外死亡影响的滞后期一般为2～3d,呼吸系统疾病包括COPD死亡的滞后期为2～5d;热浪过程中气温越高,湿度越高,对呼吸系统疾病死亡的影响越大。

Objective To explore the effects of heat wave on daily death counts in Beijing. Methods Case-crossover design was used to study the impact of five heat waves on the daily death of non-accidental death and respiratory diseases from Jan. 1, 1999 to Jun. 30, 2000. Moreover the relationship between the heat wave and chronic obstructive pulmonary disease （COPD） death were investigated. The 7th day before death was chosen as 1：1 unidirectional retrospective self-matched control. The OR of different length of risk period was calculated. The highest OR value and its corresponding risk period was utilized to reflect the impact of heat wave on daily number of non-accidental death and respiratory disease death, lag days and duration. Results There were five heat waves during the study period. The first heat wave sustained 9 days and the maximum temperature was 38.8 ℃ and average humidity was 46.7%. The OR values for the non-accidental death, respiratory disease death and COPD death were 1.442 （95%CI： 1.310-1.588）, 2.667（95%CI： 1.893-3.756） and 1.778（95%CI： 1.182-2.674） respectively. The second heat wave lasted 3 days, with the maximum temperature of 36.8 ℃ and average humidity of 61.0%. The OR values for the three causes of death were 1.200（95% CI： 0.973-1.480）, 3.000 （95%CI： 1.090-8.254） and 3.333 （95%CI： 0.917-12.112） respectively. The third heat wave continued 7 days, with the maximum temperature of 41.5 ~C, and average humidity of 58.5%. The OR values for the daily death counts caused by non-accidental, respiratory diseases and COPD were 2.135（95%CI： 1.925-2.368）, 3.360（95%CI： 2.450--4.608） and 2.897（95% CI： 1.899-4.418） respectively. The fourth lasted 3 days, with the maximum temperature of 39.6℃ and average humidity of 31.9%. The OR values for the cardiovascular disease death, cerebrovascular diseases death and acute myocardial infarction death were 1.464（95%CI：1.042-2.057）, 1.000（95%CI： 0.375-2.664） and 1.000（95%CI： 0.290-3.454） respectively. The Fifth heat wave lasted for 4 days. The maximum temperature was 37.4 ℃, and average humidity was 42.0% during the period. The OR values for daily death counts caused by non-accidental, respiratory diseases and COPD were 1.525 （95%CI： 1.099-2.118）, 2.000 （95%CI： 0.500- 7.997） and 2.000 （95%CI： 0.603-5.371） respectively. Conclusion Significant increase was seen for daily death counts in Beijing during the heat wave and there was hysteresis effect usually. The lag phase of non-accidental death is generally 2-3 days, respiratory disease including COPD death usually is 2-5 days. The daily temperature and relative humidity present a positive association with the risk of death from respiratory disease during the heat wave.