A large and compelling body of evidence has accumulated, particularly during the last two decades, that reveals a powerful role for social factors—apart from medical care—in shaping health across a wide range of health indicators, settings, and populations.^1–16 This evidence does not deny that medical care influences health; rather, it indicates that medical care is not the only influence on health and suggests that the effects of medical care may be more limited than commonly thought, particularly in determining who becomes sick or injured in the first place.^4,6,7,17,18 The relationships between social factors and health, however, are not simple, and there are active controversies regarding the strength of the evidence supporting a causal role of some social factors. Meanwhile, researchers increasingly are calling into question the appropriateness of traditional criteria for assessing the evidence.^17,19–22

The limits of medical care are illustrated by the work of the Scottish physician, Thomas McKeown, who studied death records for England and Wales from the mid-19th century through the early 1960s. He found that mortality from multiple causes had fallen precipitously and steadily decades before the availability of modern medical-care modalities such as antibiotics and intensive care units. McKeown attributed the dramatic increases in life expectancy since the 19th century primarily to improved living conditions, including nutrition, sanitation, and clean water.²³ While advances in medical care also may have contributed,^23–26 most authors believe that nonmedical factors, including conditions within the purview of traditional public health, were probably more important;²⁴ public health nursing, including its role in advocacy, may have played an important role in improved living standards.²⁷ Another example of the limits of medical care is the widening of mortality disparities between social classes in the United Kingdom in the decades following the creation of the National Health Service in 1948, which made medical care universally accessible.²⁸ Using more recent data, Martinson found that although health overall was better in the United Kingdom than in the United States, which lacks universal coverage, disparities in health by income were similar in the two countries.²⁹ Large inequalities in health according to social class have been documented repeatedly across different European countries, again despite more universal access to medical care.^30–32

Another often-cited example of the limits of medical care is the fact that, although spending on medical care in the U.S. is far higher than in any other nation, the U.S. has consistently ranked at or near the bottom among affluent nations on key measures of health, such as life expectancy and infant mortality; furthermore, the country’s relative ranking has fallen over time.^33,34 A recent report from the National Research Council and Institute of Medicine has documented that the U.S. health disadvantage in both morbidity and mortality applies across most health indicators and all age groups except those older than 75 years of age; it applies to affluent as well as poor Americans, and to non-Latino white people when examined separately.³⁵ Other U.S. examples include the observation that, while expansions of Medicaid maternity care around 1990 resulted in increased receipt of prenatal care by African American women,^36,37 racial disparities in the key birth outcomes of low birthweight and preterm delivery were not reduced.³⁸ Although important for maternal health, traditional clinical prenatal care generally has not been shown to improve outcomes in newborns.^39–44

THE IMPACTS OF SOCIOECONOMIC AND OTHER SOCIAL FACTORS ON MOST HEALTH OUTCOMES

A number of studies have attempted to assess the impact of social factors on health. A review by McGinnis et al. estimated that medical care was responsible for only 10%–15% of preventable mortality in the U.S.;⁴⁵ while Mackenbach’s studies suggest that this percentage may be an underestimate, they affirm the overwhelming importance of social factors.^25,26 McGinnis and Foege concluded that half of all deaths in the U.S. involve behavioral causes;¹⁸ other evidence has shown that health-related behaviors are strongly shaped by social factors, including income, education, and employment.^46,47 Jemal et al., studying 2001 U.S. death data, concluded that “potentially avoidable factors associated with lower educational status account for almost half of all deaths among working-age adults in the U.S.”⁴⁸ Galea and colleagues conducted a meta-analysis, concluding that the number of U.S. deaths in 2000 attributable to low education, racial segregation, and low social support was comparable with the number of deaths attributable to myocardial infarction, cerebrovascular disease, and lung cancer, respectively.⁴⁹

The health impact of social factors also is supported by the strong and widely observed associations between a wide range of health indicators and measures of individuals’ socioeconomic resources or social position, typically income, educational attainment, or rank in an occupational hierarchy. In U.S. as well as European data, this association often follows a stepwise gradient pattern, with health improving incrementally as social position rises. This stepwise gradient pattern was first noted in the United Kingdom.^28,50 Although research on the socioeconomic gradient has been more limited in the U.S., the results of U.S. studies have mirrored the European findings. Figures 1​1​​–5 illustrate a few examples using U.S. data, with social position reflected by income or by educational attainment. Using national data, the National Center for Health Statistics’ “Health, United States, 1998” documented socioeconomic gradients in the majority of numerous health indicators measured across different life stages.⁵¹ Braveman and colleagues confirmed those findings using recent U.S. data.⁵² Both Pamuk et al.⁵¹ and Braveman et al.⁵² found that socioeconomic gradient patterns predominated when examining non-Latino black and white groups but were less consistent among Latino people. Minkler and colleagues found dramatic socioeconomic gradients in functional limitations among people aged 65–74 years.  Social and Physical Determinants of Health and the Effect on virtual patient.This finding is particularly remarkable because income gradients generally tend to flatten in old age.⁵³ As illustrated in Figure 5, and in both Pamuk et al.⁵¹ and Braveman et al.,⁵² these socioeconomic gradients in health have been observed not only in the U.S. population overall, but within different racial/ethnic groups, demonstrating that the socioeconomic differences are not explained by underlying racial/ethnic differences. Indeed, most studies that have examined racial/ethnic differences in health after adjusting for socioeconomic factors have found that the racial/ethnic differences disappeared or were substantially reduced.^54–56 This does not imply that the only differences in experiences between racial/ethnic groups are socioeconomic; for example, racial discrimination could harm the health of individuals of all socioeconomic levels by acting as a pervasive stressor in social interactions, even in the absence of anyone’s conscious intent to discriminate.^57,58 Furthermore, the black-white disparity in birth outcomes is largest among highly educated women.⁵⁹ Living in a society with a strong legacy of racial discrimination could damage health through psychobiologic pathways, even without overtly discriminatory incidents.^60–62

How do widespread and persistent socioeconomic gradients in health add to evidence that social factors are important influences on health? Strong links between poverty and health have been observed for centuries.^63–65 Observing a graded relationship (as opposed to a simple threshold, for instance at the poverty line) of socioeconomic factors with many different health indicators suggests a possible dose-response relationship, adding to the likelihood that socioeconomic factors—or factors closely associated with them—play a causal role. Although the effects of abject poverty on health are rarely disputed, not everyone concurs about the effects of income and education on health across the socioeconomic spectrum. Some have argued that income-health or education-health relationships reflect reverse causation (i.e., sickness leading to income loss and/or lower educational achievement).⁶⁶ Although ill health often results in lost income, and a child’s poor health could limit educational achievement, evidence from longitudinal and cross-sectional studies indicate that these do not account for the strong, pervasive relationships observed.⁶⁷ Links between education and health, furthermore, cannot be explained by reverse causation because once attained, educational attainment is never reduced. Social and Physical Determinants of Health and the Effect on virtual patient.