摘要：Objectives. This study assessed whether income inequality and primary care physician supply have a different effect on mortality among Blacks compared with Whites. Methods. We conducted a multivariate ecologic analysis of 1990 data from 273 US metropolitan areas. Results. Both income inequality and primary care physician supply were significantly associated with White mortality ( P < .01). After the inclusion of the socioeconomic status covariates, the effect of income inequality on Black mortality remained significant ( P < .01), but the effect of primary care physician supply was no longer significant ( P > .10), particularly in areas with high income inequality. Conclusions. Improvement in population health requires addressing socioeconomic determinants of health, including income inequality and primary care availability and access. Studies in the United States and elsewhere have shown the association between wide disparities in income of the wealthy and that of the less wealthy (“income inequality”) and poor health. 1 – 8 Our previous published study showed that primary care may mitigate the adverse effects of income inequality. 9 We used 1990 US state-level data and found a significant association between higher primary care physician supply and lower mortality, longer life expectancy, and better birth outcome, even in the presence of high income inequality and other adverse sociodemographic characteristics. The literature examining the effect of income inequality on racial/ethnic disparity in health has been limited. The few studies 8 , 9 that have included race/ethnicity used it as a control variable, thus eliminating the possibility of detecting racial/ethnic differences in determinants of health. If race/ethnicity-related differences are actually a differential response to other measured factors, then simply including race/ethnicity as a control variable will not address the interaction between race/ethnicity and other independent measures. We used US metropolitan areas as the unit of analysis to assess whether income inequality and primary care physician supply have a different effect on mortality among Blacks compared with Whites, controlling for socioeconomic determinants of health. Although states are the principal sources of variation in policies affecting income inequality, metropolitan areas may be a more appropriate unit of analysis for variations in health care resources.
