Air Health Effects Division, Health Canada, University of Alberta, Edmonton, Canada.
Stroke. 2010 Jul;41(7):1319-25. doi: 10.1161/STROKEAHA.110.580571. Epub 2010 Jun 10.
Long-term air pollution effects on stroke incidence have not been examined extensively. We investigated the associations between ambient pollution and the incidence of stroke, as well as stroke subtypes, in a northern Canadian city surrounded by energy-sector pollution sources.
Stroke data from an administrative database from 2003 through 2007 were used to estimate annual incidence rates within small geographic regions within Edmonton, Canada. Air pollution levels for each region were estimated from continuous fixed-site monitoring stations in and around Edmonton. We fit models estimating stroke risk in relation to pollution levels; risks were adjusted for age, sex, income, social deprivation, and other factors.
Between 2003 and 2007, the average 5-year concentration of NO(2) and CO was positively associated with the incidence of stroke, particularly for hemorrhagic and nonhemorrhagic stroke subtypes (NO(2): hemorrhagic stroke relative risk=1.46; 95% CI, 1.19-1.80; nonhemorrhagic stroke relative risk=1.36; 95% CI, 1.19-1.56). However, these estimates of risk diminished after controlling for the ecological measures of income and deprivation. Adjustment for ecologically derived indices of smoking, hypertension, and body mass index did not alter the estimates of risk in any meaningful way.
Although long-term NO(2) and CO levels were positively associated with a higher incidence of stroke in the entire study area, the risk estimates were strongly attenuated by household income levels. Further research that incorporates individual-level risk factor data would improve our understanding of the relation of longer-term exposures to ambient air pollution and stroke outcomes.
长期的空气污染对中风发病率的影响尚未得到广泛研究。我们在加拿大北部一个被能源部门污染源环绕的城市，调查了环境污染物与中风发病率以及中风亚型之间的关系。
利用来自加拿大埃德蒙顿市的行政数据库中 2003 年至 2007 年的中风数据，在埃德蒙顿及其周边的固定监测站估计每个地区的空气污染水平，用以估算该地区内小地理区域的中风年发病率。我们拟合了模型，估算与污染水平相关的中风风险；风险调整因素包括年龄、性别、收入、社会贫困程度以及其他因素。
在 2003 年至 2007 年期间，NO2 和 CO 的平均 5 年浓度与中风发病率呈正相关，尤其是与出血性和非出血性中风亚型相关（NO2：出血性中风相对风险=1.46；95%可信区间，1.19-1.80；非出血性中风相对风险=1.36；95%可信区间，1.19-1.56）。然而，在控制了收入和贫困程度的生态指标后，这些风险估计值会降低。通过生态衍生的吸烟、高血压和体重指数指数进行调整，不会对风险估计值产生任何有意义的改变。
尽管长期的 NO2 和 CO 水平与整个研究区域内更高的中风发病率呈正相关，但家庭收入水平强烈削弱了风险估计值。进一步的研究，结合个体风险因素数据，将有助于提高我们对长期暴露于环境空气污染与中风结局之间关系的理解。
