空氣懸浮微粒與到院前心跳停止發生率之相關性研究

Abstract

背景 心因性猝死是已開發國家民眾之重要死因。在過去的研究中顯示，心因性猝死的發生會隨著晝夜、星期、季節的不同而產生週期性的變動。許多動物及人體研究的結果，提供了空氣污染的暴露和心血管疾病之相關致病機轉。到院前心跳停止是指在醫院外發生的心因性猝死，此研究在探討空氣懸浮微粒與到院前心跳停止病患發生率之相關性。 材料與方法 所有在2003年9月到2007年12月間，登錄在台北市緊急醫療網的成人到院前心跳停止病患均收錄在本研究中，排除條件為創傷、在現場沒有進行急救以及以事先聲明不要進行急救的病患。氣象及空氣污染指標包括一氧化碳、二氧化硫、氮氧化物、臭氧、空氣懸浮微粒(PM2.5和PM10)及氣溫等資料，是經由台灣環保署所取得。對於到院前心跳停止病患及空氣污染資料，將會進行描述性統計和分析。在時間序列分析中，將會採用卜瓦松迴歸模型(Poisson regression model)及廣義加法模型(generalized additive mode)，對於每日空氣污染濃度及每日的到院前心跳停止病患數，進行相關分析。在個案交叉(case-crossover)分析中，會採取每日時間及每週星期的配對來選取對照組，進而探討空氣污染濃度和到院前心跳停止的發生其相關性。在相關性分析中亦會進行敏感度分析和效應修正(effect modification)的探討。 結果 在研究期間共有6341個符合條件的到院前心跳停止病患，其平均年齡為71.7歲，男性多於女性。每日上午6點到10點以及下午5點到8點是發生到院前心跳停止的尖峰期，冬季的個案發生率明顯增加，在星期一、五、六和日的個案發生率也是比較高。空氣中一氧化碳和氮氧化物的濃度存在高度相關，兩種懸浮微粒(PM2.5和PM10)的濃度也是彼此相關。 時間序列分析的結果顯示，懸浮微粒濃度的上升和到院前心跳停止發生率呈現正相關的趨勢。在個案交叉(case-crossover)分析中，24小時前的懸浮微粒(PM2.5和PM10) 24小時平均濃度，和到院前心跳停止的發生率，有統計上明顯的正相關。PM10之濃度每增加一個四分位間距(interquartile range)或29.01 µg/m3，發生到院前心跳停止的勝算比(odds ratio)為1.054，其95%信賴區間為1.017至1.093。PM2.5之濃度每增加一個四分位間距(interquartile range)或19.21 ug/m3，發生到院前心跳停止的勝算比(odds ratio)為1.060，其95%信賴區間為1.022至1.099。這樣的相關性在男性以及年齡40到74歲的族群更加明顯。 研究限制 到院前心跳停止的病患不見得會真的暴露在空氣污染之中，病患的真實暴露和空氣污染測量站的數值之間可能存在偏差。在緊急醫療網資料庫中有限的個人資料，限制了時間序列分析的能力以及效應修正範圍上的探討。 結論 空氣懸浮微粒和到院前心跳停止的發生是存在正相關的連結，空氣污染的防制可能可以成為減少心血管疾病死亡的預防措施。 關鍵字：懸浮微粒，空氣污染，心因性猝死，心跳停止，心血管疾病

Background Sudden cardiac death is the leading cause of death in developed countries. Circadian, weekly, and seasonal variations in the incidence of sudden cardiac death have been observed. Numerous animal and human studies provide biological evidence linking air pollution exposure and cardiovascular disease. Sudden cardiac death occurring outside hospital is usually referred to as out-of-hospital cardiac arrest (OHCA). This study was conducted to investigate the association between particulate matter (PM) and the incidence of OHCA. Material and Methods All adult OHCA patients that activated the emergency medical service system in Taipei city from September 2003 through December 2007 were included in the study. Patients with traumatic injuries, and patients for whom resuscitation was not attempted by emergency medical service personnel due to terminal illness or an existing do-not-attempt-resuscitate order were excluded. The data of climate and air pollution measurements, including carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxide (NO), nitrogen dioxide (NO2), ozone (O3), particulate matters (PM2.5 and PM10), and temperature were obtained from the Taiwan Environmental Protection Administration. Descriptive analyses of the study targets and air pollution data were performed. In the time-series analysis, Poisson regression models and generalized additive models were applied to analyze the association between daily-averaged air pollutant levels and daily OHCA patient numbers. The case-crossover design with matching by hour-of-day and day-of-week was used to explore the association between the incidence of OHCA and air pollution levels. Sensitivity analysis and investigations on effect modification were performed. Results There were 6341 cases of OHCA during the study period. The mean age was 71.7 years, and the study targets included more men than women. Circadian variation was observed, with a maximum occurrence rate between 6 and 10 AM and a secondary evening peak between 5 and 8 PM. There were significantly more OHCA patients during winter. Compared to other weekdays, there were significantly more OHCA patients on Monday, Friday, Saturday, and Sunday. There was high correlation between CO, NO, NO2 and NOx levels. PM2.5 was also highly correlated with PM10. In the time-series analysis, positive trends indicated that increasing PM10 and PM2.5 levels were associated with increasing incidence of OHCA. However, in the case-crossover analysis, the 24-hour mean PM10 and PM2.5 levels with 24-hour lag were significantly associated with the incidence of OHCA. For an increase of one interquartile range (29.01 µg/m3 ) in PM10, the odds ratio estimate for OHCA was 1.054 (95% confidence interval: 1.017- 1.093). For an increase of one interquartile range (19.21 µg/m3) in PM2.5, the odds ratio estimate for OHCA was 1.060 (95% confidence interval: 1.022- 1.099). These associations were stronger in males and in the 40- 74-year group. Limitations There is no assurance that OHCA patients were indeed exposed to air pollution. Discrepancies between ambient and actual personal exposures may exist. Limited personal information in the database restricted the power of time-series analysis and the extent of exploring effect modification. Conclusion Particulate matter is positively associated with the incidence of OHCA. Controlling air pollution may be a preventable means to decrease cardiovascular mortality. Key words: particulate matter, air pollution, sudden cardiac death, cardiac arrest, cardiovascular disease.