Trends in air pollution and mortality - An approach to the assessment of unmeasured confounding
Trends in air pollution and mortality - An approach to the assessment of unmeasured confounding
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DOI：
10.1097/ede.0b013e31806462e9
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发表时间：
2007-07-01
期刊：
影响因子：
5.4
通讯作者：
Zeger, Scott L.
中科院分区：
文献类型：
--
作者：
Janes, Holly;Dominici, Francesca;Zeger, Scott L.
我们提出了一种方法，用于诊断混淆偏见下的模型，链接的空间和时间变化的暴露和健康结果。我们将关联分解成正交分量，对应于不同的空间和时间尺度的变化。如果模型完全控制了混杂因素，则暴露效应估计值在不同的时间和空间尺度上应该相等。我们发现，整体暴露效应估计是一个加权平均的尺度特定的暴露效应estimates.我们使用这种方法来估计细颗粒物（PM2.5）的月平均值之间的关联在过去的12个月和每月死亡率在113个美国县从2000年到2002年。我们将PM2.5与死亡率之间的关联分解为两个组成部分：（1）PM2.5与死亡率的“全国趋势”之间的关联;以及（2）“地方趋势”之间的关联，定义为特定于国家的偏离全国趋势。这第二个组成部分提供的证据，是否县有陡峭的下降PM2.5也有陡峭的下降死亡率相对于他们的国家trends.We发现，暴露效应估计是不同的，在这2个时空尺度，这引起了人们对混淆偏差的关注。我们认为，在全国范围内，PM2.5趋势与死亡率之间的关联比PM2.5趋势与地方范围内死亡率之间的关联更容易混淆。如果将全国范围内的关联放在一边，几乎没有证据表明12个月暴露于PM2.5与死亡率之间存在关联。
We propose a method for diagnosing confounding bias under a model that links a spatially and temporally varying exposure and health outcome. We decompose the association into orthogonal components, corresponding to distinct spatial and temporal scales of variation. If the model fully controls for confounding, the exposure effect estimates should be equal at the different temporal and spatial scales. We show that the overall exposure effect estimate is a weighted average of the scale-specific exposure effect estimates.We use this approach to estimate the association between monthly averages of fine particles (PM2.5) over the preceding 12 months and monthly mortality rates in 113 US counties from 2000 to 2002. We decompose the association between PM2.5 and mortality into 2 components: (1) the association between "national trends" in PM2.5 and mortality; and (2) the association between "local trends," defined as county-specific deviations from national trends. This second component provides evidence as to whether counties having steeper declines in PM2.5 also have steeper declines in mortality relative to their national trends.We find that the exposure effect estimates are different at these 2 spatiotemporal scales, which raises concerns about confounding bias. We believe that the association between trends in PM2.5 and mortality at the national scale is more likely to be confounded than is the association between trends in PM2.5, and mortality at the local scale. If the association at the national scale is set aside, there is little evidence of an association between 12-month exposure to PM2.5, and mortality.