Achilleos Souzana, Kioumourtzoglou Marianthi-Anna, Wu Chih-Da, Schwartz Joel D, Koutrakis Petros, Papatheodorou Stefania I
Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA.
Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York, NY, USA.
Environ Int. 2017 Dec;109:89-100. doi: 10.1016/j.envint.2017.09.010. Epub 2017 Oct 5.
The link between PM exposure and adverse health outcomes is well documented from studies across the world. However, the reported effect estimates vary across studies, locations and constituents. We aimed to conduct a meta-analysis on associations between short-term exposure to PM constituents and mortality using city-specific estimates, and explore factors that may explain some of the observed heterogeneity.
We systematically reviewed epidemiological studies on particle constituents and mortality using PubMed and Web of Science databases up to July 2015.We included studies that examined the association between short-term exposure to PM constituents and all-cause, cardiovascular, and respiratory mortality, in the general adult population. Each study was summarized based on pre-specified study key parameters (e.g., location, time period, population, diagnostic classification standard), and we evaluated the risk of bias using the Office of Health Assessment and Translation (OHAT) Method for each included study. We extracted city-specific mortality risk estimates for each constituent and cause of mortality. For multi-city studies, we requested the city-specific risk estimates from the authors unless reported in the article. We performed random effects meta-analyses using city-specific estimates, and examined whether the effects vary across regions and city characteristics (PM concentration levels, air temperature, elevation, vegetation, size of elderly population, population density, and baseline mortality).
We found a 0.89% (95% CI: 0.68, 1.10%) increase in all-cause, a 0.80% (95% CI: 0.41, 1.20%) increase in cardiovascular, and a 1.10% (95% CI: 0.59, 1.62%) increase in respiratory mortality per 10μg/m increase in PM. Accounting for the downward bias induced by studies of single days, the all-cause mortality estimate increased to 1.01% (95% CI: 0.81, 1.20%). We found significant associations between mortality and several PM constituents. The most consistent and stronger associations were observed for elemental carbon (EC) and potassium (K). For most of the constituents, we observed high variability of effect estimates across cities.
Our meta-analysis suggests that (a) combustion elements such as EC and K have a stronger association with mortality, (b) single lag studies underestimate effects, and (c) estimates of PM and constituents differ across regions. Accounting for PM mass in constituent's health models may lead to more stable and comparable effect estimates across different studies.
PROSPERO: CRD42017055765.
世界各地的研究充分证明了接触细颗粒物（PM）与不良健康后果之间的联系。然而，不同研究、地点和成分的报告效应估计值有所不同。我们旨在使用特定城市的估计值对短期接触PM成分与死亡率之间的关联进行荟萃分析，并探讨可能解释部分观察到的异质性的因素。
我们使用PubMed和Web of Science数据库系统回顾了截至2015年7月关于颗粒物成分与死亡率的流行病学研究。我们纳入了研究一般成年人群中短期接触PM成分与全因、心血管和呼吸系统死亡率之间关联的研究。每项研究根据预先指定的研究关键参数（如地点、时间段、人群、诊断分类标准）进行总结，并且我们使用健康评估与翻译办公室（OHAT）方法评估每项纳入研究的偏倚风险。我们提取了每种成分和死亡原因的特定城市死亡率风险估计值。对于多城市研究，除非文章中有报告，我们向作者索要特定城市的风险估计值。我们使用特定城市的估计值进行随机效应荟萃分析，并检查效应是否因地区和城市特征（PM浓度水平、气温、海拔、植被、老年人口规模、人口密度和基线死亡率）而异。
我们发现，每增加10μg/m³的PM，全因死亡率增加0.89%（95%置信区间：0.68，1.10%），心血管死亡率增加0.80%（95%置信区间：0.41，1.20%），呼吸系统死亡率增加1.10%（95%置信区间：0.59，1.62%）。考虑到单日研究引起的向下偏倚，全因死亡率估计值增至1.01%（95%置信区间：0.81，1.20%）。我们发现死亡率与几种PM成分之间存在显著关联。对于元素碳（EC）和钾（K），观察到的关联最为一致且更强。对于大多数成分，我们观察到不同城市间效应估计值的高度变异性。
我们的荟萃分析表明，（a）如EC和K等燃烧元素与死亡率的关联更强，（b）单滞后研究低估了效应，（c）不同地区PM及其成分的估计值存在差异。在成分的健康模型中考虑PM质量可能会导致不同研究间的效应估计值更稳定且具有可比性。
PROSPERO：CRD42017055765。
