Today's entry in the Lexicon is "Social Determinants of Health." Perhaps the most basic way to introduce this topic is simply to ask, what causes health, or the lack thereof?
There are many possible answers to this question. Perhaps, in the classical spirit, we might attempt to come out this question by assessing the negative -- what causes poor health? One obvious answer is "microorganisms" or other infectious agents. Another, obviously topical response might be "poor access to care." Smoking has long been linked to poor health, as has poor nutrition, substance abuse, and so on and so forth.
These answers all seem plausible, but a significant body of research suggests that they are rather inadequate to account for poor health, at least in the aggregate. Why?
The short answer is that they are too far down the causal chain. While it is accurate to say that substance abuse causes poor health, addressing the argument itself seems to require assessing why exactly some people, indeed, some societies, show dramatic levels of substance abuse. Here, we finally come to the idea that social structures -- history, politics, culture -- exert at the highest level a profound influence on health. It is analysis of these social structures that best explains prevalence patterns of substance abuse. For example, can it truly be coincidence that indigenous populations on opposite sides of the globe display unbelievably high prevalence of substance abuse? Both Native Americans and Aborigines, victims of horrifying structural violence, to use Paul Farmer's term, have such prevalence.
Similarly, the insights of social epidemiologists like Marmot in the U.K., and Kawachi and Kennedy in the U.S., show that a relative socioeconomic gradient correlates robustly with health. In English, this means simply that the higher your socioeconomic standard, the more healthy you are likely to be. Because the gradient is relative, it means not just that the rich are healthier than the poor, but the really rich are healthier than the slightly less well-off, who in turn are healthier than the slightly less well-off, etc, etc.
Daniels, Kawachi, and Kennedy posit some causal pathways for the correlation, in particular noting that countries with significant investments in education for the population from a young age strongly predicts health. In addition, they note that income inequality tends to undermine social cohesion, which in turn results in much lower political and civic participation, which tends to reinforce entrenched inequities.
There are further demonstrations that social factors are the most powerful determinants of health. Some might object to the analysis thus far by arguing that drugs are incredibly important determinants of health. To be sure, biologics and devices have an important role to play in care. The assessment required here is one of relative priority -- what are the primary causal factors of population health? And on this question, there is significant reason to doubt that drugs and devices exert a prominent, widespread effect.
For example, we know quite well that chemotherapeutics had little to do with the dramatic health transition (assessed by reduction of mortality) between 1800 and 1940. The reasons for the epidemiologic shift remain hotly disputed, but it is relatively clear that drugs were a negligible factor. Moreover, a relatively reliable vaccine for smallpox was common knowledge since the late 18th century; yet this knowledge did not prevent significant smallpox epidemics throughout the 19th century. We have extremely effective treatments for malaria; yet approximately 1 million people, most of them children, die from the illness every year in Africa.
Amartya Sen showed over 25 years ago that contrary to popular belief (then and now), physical conditions apparently did not cause famine. His analysis definitively demonstrated that in regions with virtually identical climates and geographical factors (such as drought, flood, etc.), some regions prospered while others suffered greatly. The difference, he identified, was the social and political structures, and in particular the government structures. There was no lack of humanitarian aid and food in these regions; in some of them, human agency prevented them from reaching those who most needed it.
In any case, there is a great deal more that could be said about this, and, in point of fact, multiple books and articles have been written on the subject. One immediate implication for U.S. culture is that the strident emphasis on individual responsibility for health may be somewhat misplaced. This is not to suggest that such responsibility has no role in health, but simply that social structures may exert a significantly larger causal effect on health.
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Bibliography
Amartya Sen, An Essay on Entitlement and Deprivation (New York: Oxford University Press, 1981).
Norman Daniels, Bruce Kennedy, & Ichiro Kawachi, Is Inequality Bad for Our Health? (Boston: Beacon Press, 2000).
Social Determinants of Health, eds. Michael Marmot, Richard G. Wilkinson, 2d ed. (New York: Oxford University Press, 2005).
Paul Farmer, Pathologies of Power (Berkeley, CA: University of California Press, 2004).
The Social Medicine Reader, Vol II, eds. Gail E. Henderson et al., 2d. ed (Durham, NC: Duke University Press, 2005).
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