Historical roots of social epidemiology: socioeconomic gradients in health and contextual analysis

Nancy Krieger

Department of Health and Social Behavior, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Email: nkrieger{at}hsph.harvard.edu

Sir—In recent years, social epidemiologists have brought to the fore two seemingly new observations:

  1. a socioeconomic gradient in health exists, extending from top to bottom ranks of society, not simply a poverty threshold that separates those with awful versus good health;12 and
  2. context and level matter: poor people living in poor neighbourhoods are likely to have poorer health than equally poor people living in more affluent neighbourhoods.34

Together, these observations offer important challenges to aetiologic explanations and policy interventions.

But are these observations in fact new? Or is it that contemporary scientists—and perhaps policy makers—are once again willing to engage with questions initially raised during the formative days of epidemiology as a discipline, in the early 19th century?5

Consider, for example, research conducted by one of the earliest and foremost investigators linking population health to political economy: Louis René Villermé (1782–1863).67 A French physician and liberal supporter of the free market, in the mid-1820s Villermé creatively employed newly amassed and unprecedented Parisian census data to produce a novel finding. His classic 1826 study demonstrated empirically, for the first time for any city anywhere, that variations in annual mortality rates across neighbourhoods—even in non-epidemic years—were patterned by poverty and wealth, as opposed to the ‘natural environment’ of Hippocratic doctrine.8 Moreover, death rates not only were highest among areas whose residents paid the least in ‘untaxed rents’, a type of tax paid only by the wealthy, but also clearly exhibited a continuous socioeconomic gradient (Table 1Go).


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Table 1 Average annual mortality à domicile (in households) of rich and poor, by arrondissement, 1817–1821, Paris8(pp.227)
 
Consider, too, the studies that Friedrich Engels (1820–1895) drew upon to prepare his classic account of the impact of early industrialization on health: The Condition of the Working Class in England,910 written in 1844. As recently pointed out by George Davey Smith,11 in this work Engels cited evidence regarding higher mortality among poor houses in poor compared to ‘improved’ streets (Table 2Go), illustrating that context matters. Engels also emphasized the importance of early life deprivation on adult health,9(pp.118–19,169,180–83,237–38) an insight next forcefully re-emerging in the 1930s in the works of such leading researchers such as Edgar Sydenstricker (1881–1936)12 and William O Kermack (1898–1970),1315 and now generating a large research programme.1517Other examples can readily be found, including 19th and early 20th century research adducing that racial discrimination at any economic level can harm health among African Americans, above and beyond—and also compounding—socioeconomic deprivation brought about by such discrimination.1822


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Table 2 Mortality by class of street and class of house, Chorlton-on-Medlock, a suburb of Manchester, United Kingdom, 18449(pp.120–21)
 
Recognizing these prior social epidemiological insights in no way discounts the importance of new 21st century research on these same topics, especially studies enhanced by new methodological and aetiologic discoveries.14, 2326 It does, however, suggest that the value of contemporary social epidemiology lies as much, if not more, in its continued salience, rather than its novelty. The net implication? We do a disservice to the weight of evidence, past and present, on social inequalities in health if we suggest that what chiefly hampers efforts to promote social equity in health is a lack of knowledge, whether of the social patterning of health, or trends, or pathways. Better instead to delineate explicitly persisting and changing structural and political determinants of these persisting—and changing—inequalities, including who deliberately or inadvertently benefits from these inequalities, so as to inform efforts to secure social equity in health. Staying grounded in history can help us both avoid notions of a technocratic ‘quick fix’ and deepen the meaningful contributions social epidemiologists can make to public democratic debate over social determinants of well-being.

References

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2 Marmot M, Ryff CD, Bumpass LL, Shipley M, Marks NF. Social inequalities in health: next questions and converging evidence. Soc Sci Med 1997;44:901–10.[ISI][Medline]

3 Diez-Roux AV. Bringing context back into epidemiology: variables and fallacies in multilevel analysis. Am J Public Health 1998;88:216–22.[Abstract]

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9 Engels F. The condition of the working class in England. (1845) Translated by Henderson WO and Chaloner WH. Stanford, CA: Stanford University Press, 1958.

10 Marcus S. Engels, Manchester & the working class. New York: Vintage Books, 1974.

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12 Sydenstricker E. Health and environment. New York: McGraw-Hill, 1933.

13 Kermack WO, McKendrick AG, McKinlay PL. Death rates in Great Britain and Sweden: some general regularities and their significance. Lancet 1934;226:698–703.

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19 Ernst W, Harris B (eds). Race, science and medicine, 1700–1960. London: Routledge, 1999.

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21 Nathan WB. Health conditions in North Harlem, 1923–1927. New York: National Tuberculosis Association, 1932.

22 Krieger N. Discrimination and health. In: Berkman L, Kawachi I (eds). Social epidemiology. Oxford: Oxford University Press, 2000, pp.36–75.

23 Berkman L, Kawachi I (eds). Social epidemiology. Oxford: Oxford University Press, 2000.

24 Marmot M, Wilkinson RG (eds). Social determinants of health. Oxford: Oxford University Press, 1999.

25 Leon D, Walt G (eds). Poverty, inequality, and health: an international perspective. Oxford: Oxford University Press, 2001.

26 Young TK. Population health: concepts and methods. New York: Oxford University Press, 1998.