Yang Dongyan, Howard George, Coffey Christopher S, Roseman Jeffrey
Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, Ala, USA.
Neuroepidemiology. 2004 May-Jun;23(3):118-22. doi: 10.1159/000075954.
The excess stroke mortality among African Americans and Southerners is well known. Because a higher proportion of the population living in the 'Stroke Belt' is African American, then a portion of the estimated excess risk of stroke death traditionally associated with African-American race may be attributable to geography (i.e., race and geography are 'confounded'). In this paper we estimate the proportion of the excess stroke mortality among African Americans that is attributable to geography.
The numbers of stroke deaths at the county level are available from the vital statistics system of the US. A total of 1,143 counties with a population of at least 500 whites and 500 African Americans were selected for these analyses. The black-to-white stroke mortality ratio was estimated with and without adjustment for county of residence for those aged 45-64 and for those aged 65 and over. The difference in the stroke mortality ratio before versus after adjustment for county provides an estimate of the proportion of the excess stroke mortality inappropriately attributed to race (that is in fact attributable to geographic region).
For ages 45-64, the black-to-white stroke mortality ratio was reduced from 3.41 to 3.04 for men, and from 2.82 to 2.60 for women, suggesting that between 10 and 15% of the excess mortality traditionally attributed to race is rather due to geography. Over the age of 65, the black-to-white stroke mortality ratio was reduced from 1.31 to 1.27 for men, and from 1.097 to 1.095 for women, suggesting that between 2 and 13% of the excess mortality attributed to black race is actually attributable to geography. The reductions of all the four age strata gender groups were highly significant.
These results suggest that a significant, although relatively small, proportion of the excess mortality traditionally attributed to race is rather a factor of geography.
非裔美国人和南方人的中风死亡率过高是众所周知的。由于生活在“中风带”的人口中，非裔美国人占比更高，因此传统上与非裔美国人种族相关的中风死亡额外风险的一部分可能归因于地理位置（即种族和地理位置“混淆”）。在本文中，我们估计了非裔美国人中风死亡率过高中可归因于地理位置的比例。
县级中风死亡人数可从美国生命统计系统获得。共选择了1143个县进行分析，这些县的白人人口和非裔美国人口至少各有500人。对45 - 64岁以及65岁及以上人群，分别估计了调整居住县前后的黑/白中风死亡率比。调整县因素前后中风死亡率比的差异，提供了对不恰当地归因于种族（实际上归因于地理区域）的中风额外死亡率比例的估计。
对于45 - 64岁人群，男性的黑/白中风死亡率比从3.41降至3.04，女性从2.82降至2.60，这表明传统上归因于种族的额外死亡率中有10%至15%实际上是由地理位置导致的。65岁以上人群中，男性的黑/白中风死亡率比从1.31降至1.27，女性从1.097降至1.095，这表明归因于黑人种族的额外死亡率中有2%至13%实际上可归因于地理位置。所有四个年龄层性别组的降幅都非常显著。
这些结果表明，传统上归因于种族的额外死亡率中，有相当一部分（尽管相对较小）实际上是地理位置因素造成的。
