General Medical Disciplines, Stanford University School of Medicine, Stanford, California, United States of America.
PLoS One. 2012;7(4):e32930. doi: 10.1371/journal.pone.0032930. Epub 2012 Apr 17.
Life expectancy at birth, estimated from United States period life tables, has been shown to vary systematically and widely by region and race. We use the same tables to estimate the probability of survival from birth to age 70 (S(70)), a measure of mortality more sensitive to disparities and more reliably calculated for small populations, to describe the variation and identify its sources in greater detail to assess the patterns of this variation. Examination of the unadjusted probability of S(70) for each US county with a sufficient population of whites and blacks reveals large geographic differences for each race-sex group. For example, white males born in the ten percent healthiest counties have a 77 percent probability of survival to age 70, but only a 61 percent chance if born in the ten percent least healthy counties. Similar geographical disparities face white women and blacks of each sex. Moreover, within each county, large differences in S(70) prevail between blacks and whites, on average 17 percentage points for men and 12 percentage points for women. In linear regressions for each race-sex group, nearly all of the geographic variation is accounted for by a common set of 22 socio-economic and environmental variables, selected for previously suspected impact on mortality; R(2) ranges from 0.86 for white males to 0.72 for black females. Analysis of black-white survival chances within each county reveals that the same variables account for most of the race gap in S(70) as well. When actual white male values for each explanatory variable are substituted for black in the black male prediction equation to assess the role explanatory variables play in the black-white survival difference, residual black-white differences at the county level shrink markedly to a mean of -2.4% (+/-2.4); for women the mean difference is -3.7% (+/-2.3).
出生时的预期寿命，根据美国时期生命表进行估计，已被证明会因地区和种族而系统地广泛变化。我们使用相同的表来估计从出生到 70 岁的存活率（S(70)），这是一种对差异更敏感且更可靠地计算小人口的死亡率指标，以更详细地描述这种变化，并确定其来源，以评估这种变化的模式。检查每个美国县的未调整的 S(70)概率，这些县有足够的白人和黑人人口，可以发现每个种族-性别群体的巨大地理差异。例如，出生在 10%最健康的县的白人男性有 77%的概率活到 70 岁，但如果出生在 10%最不健康的县，则只有 61%的机会。每个性别的白人女性和黑人也面临类似的地理差异。此外，在每个县内，黑人与白人之间的 S(70)差异很大，男性平均相差 17 个百分点，女性平均相差 12 个百分点。在每个种族-性别组的线性回归中，几乎所有的地理差异都由一组共 22 个社会经济和环境变量来解释，这些变量是根据先前怀疑对死亡率有影响的因素选择的；R(2)范围从白人男性的 0.86 到黑人女性的 0.72。在每个县内分析黑人和白人的生存机会发现，相同的变量也解释了 S(70)中大部分种族差距。当将每个解释变量的实际白人男性值代入黑人男性预测方程中以评估解释变量在黑人和白人的生存差异中所起的作用时，县一级的黑人和白人残余差异明显缩小到平均值为-2.4%（+/-2.4）；对于女性，平均差异为-3.7%（+/-2.3）。
