Hierarchy is associated with health- Resolving what it is about hierarchy that influences health has important implications for health and social policy. Large gradients in health status and life expectancy by income level, education and occupation were repeatedly observed in various parts of the developed world in the 20th century (Antonovsky 1967; Cassel 1976; Marmot and McDowell 1986; van der Meer and Mackenbach 1998). Income, education, and occupation indicators are interrelated and, individually and in various combinations, have been used to measure socioeconomic status (SES). That associations between SES and morbidity and mortality are found for each indicator suggests some underlying primary causal process, correlated with relative social position, which expresses itself through pathways of health and disease.
Much research has targeted a better understanding of health disparities. Disease incidence, mental illness, morbidity and mortality have been shown to vary between groups rated, in terms of SES, as more or less ‘advantaged’ or ‘disadvantaged.’ Multiple studies have generated strikingly similar conclusions about the reduced life expectancy, greater frequency of chronic disease, and greater prevalence of behavioural and affective disorders for disadvantaged versus advantaged groups (Bennett 1995; Fiscella and Franks 1997; Lantz et al. 1998; Shouls et al. 1996).
That low'SES groups are characterised by obesity, poor diet and physical inactivity, and are deprived of adequate medical care and exposed to environmental pollutants, crowding, sub-standard housing, violence, and infection does not fully explain the relationship between SEvS and health. Risk factors (eg, poor diet, physical inactivity, or obesity) and risk conditions (eg, social, or living, conditions) differ by level of SES in their distribution and relationship to health. An underlying causal determinant of the relationship between SES and health appears to operate across the entire range of SES. It has become clear that the impact of SES on health is not a threshold effect due to poverty, but is a graded effect across the social hierarchy (hence the term ‘social gradient’) (Adler et al. 1994).
The Whitehall study (which takes advantage of the ranked grades of employment in the British civil service) is probably the most telling of the studies examining the social gradient in health outcome. Compared to the top administrators, the relative risk of mortality over 10 years was 1.6 for the professional-executive grades, 2.2 for the clerical grades, and 2.7 for the unskilled workers (Marmot et al. 1984).