Is inequality killing us? Atul Gawande, the New Yorker‘s resident physician-reporter, raised a vexing question about health disparities in an interview with Ezra Klein. Gawande noted that in McAllen, Texas—the community that he recently featured as an example of runaway medical costs—income inequality seems to have an effect on health separate from poverty itself. That is, an extreme economic gap carries structural harms in addition to the problems that come with simply being poor.

I think the really interesting thing is that even beyond the baseline amount of poorer health associated with lower incomes, there’s this whole body of powerful literature showing that levels of inequality are even more highly correlated with poor health. So a place like Texas has poverty, yes, but also huge inequity of income. States with similar poverty but less inequity of income have much better health profiles. I’ve actually had this on my list to write about. I don’t completely understand what it is about inequality that drives that. For instance, there’s something protective about rural areas, where there’s less inequality, so if you take rural areas and urban areas with similar levels of poverty, the rural areas will be healthier. And people say these areas are more socially cohesive and that’s what does it. But how does that make cancer rates lower?

The equality-health question, explored in numerous studies, strikes at the heart of the health care reform debate: the system is a microcosm of how resources and well-being are distributed throughout society. Reform efforts must wrestle with the issue of whether the private market can really sustain people’s health when so much of health is bound up in the overarching social structure. In a National Bureau of Economic Research analysis published in 2003, researcher Angus Deaton found a complex connection between mortality and inequality. The exact casual chain is unclear, but the fascinating thing is how race stands out as a unique determinant:

In both the state and the city data, mortality is positively and significantly correlated with almost any measure of income inequality. Because whites have higher incomes and lower mortality rates than blacks, places where the population has a large fraction of blacks are also places where both mortality and income inequality are relatively high. However, the relationship is robust to controlling for average income (or poverty rates) and also holds, albeit less strongly, for black and white mortality separately. Nevertheless, it turns out that race is indeed the crucial omitted variable. In states, cities, and counties with a higher fraction of African-Americans, white incomes are higher and black incomes are lower, so that income inequality (through its interracial component) is higher in places with a high fraction black. It is also true that both white and black mortality rates are higher in places with a higher fraction black and that, once we control for the fraction black, income inequality has no effect on mortality rates…. None of this tells us why the correlation exists, and what it is about cities with substantial black populations that causes both whites and blacks to die sooner.

But Deaton adds that other kinds of inequality may be bigger factors, citing studies in which apparent impacts of socioeconomic inequality "vanish once we control for racial composition. I suggest that inequality may indeed be important for health, but that income inequality is less important than other dimensions, such as political or gender inequality." Such studies seem to confirm what we can easily intuit from looking around our neighborhoods: the toxic intersection of the color line, class divides, and health barriers. For disadvantaged individuals as well as the social system that has failed them, the synergy of racial and socioeconomic inequities could prove deadly. Image: Emergency room at a hospital in Madera, CA. (Gary Kazanjian / AP)