"The initial study, the Whitehall I Study, was conducted over a period of ten years, beginning in 1967. A second phase, the Whitehall II Study, examined the health of 10,308 civil servants aged 35 to 55, of whom two thirds were men and one third women. A long-term follow-up of study subjects from the first two phases is ongoing.
The initial Whitehall study found lower grades, and thus status, were clearly associated with greater propensities for significant risk factors, including obesity, smoking, reduced leisure time and physical activity, more baseline illness, higher blood pressure, and shorter height. Controlling for these risk factors accounted for no more than 40% of grade differences in cardiovascular disease mortality. Even after these standard risk factors were controlled for, the lowest grade still had a relative risk of 2.1 for cardiovasular disease mortality compared to the highest grade.
The Whitehall studies have dispelled two myths. The first is that people in high status jobs have higher risks of heart disease. The second is that the gradient of health in industrialised societies is simply a matter of poor health for the disadvantaged and good health for everyone else.
How did the Whitehall studies dispel these misconceptions? The first Whitehall Study compared mortality of people in the highly stratified environment of the British Civil Service. It showed that among British civil servants, none of whom was poor in the absolute sense, there was a social gradient in mortality that ran from the bottom to the top of society. The more senior you were in the employment hierarchy, the longer you might expect to live compared to people in lower employment grades. Twenty years later, the Whitehall II study documented a similar gradient in morbidity in women as well as men. A striking finding from the Whitehall Studies was that the social gradient was observed for a range of different diseases: heart disease, some cancers, chronic lung disease, gastrointestinal disease, depression, suicide, sickness absence, back pain and general feelings of ill-health. A major challenge, and a reason for the importance of these studies, was to understand the causes of this social distribution of so many disorders.
The Whitehall studies have gone some way towards unravelling the mystery of why someone in the middle of the social hierarchy should have worse health than those above them and better health than those below them."
http://en.wikipedia.org/wiki/Whitehall_Study "The same finding has been replicated in other countries. In Spain, for example, we performed a similar study, looking at life expectancy by social class, and we found that the members of the bourgeoisie (the European term to define the corporate class) live an average of two years longer than the petit bourgeoisie (the term to define the upper middle class), who live two years longer than the middle class, who live two years longer than the skilled working class, who live two years longer than the members of the unskilled working class, who live two years longer than the unskilled working class that has been chronically unemployed. The difference between the two poles—the corporate class and the chronically unemployed—is ten years. This average distance in the European Union is seven years. In the United States, it is 14 years.2
Why these differences in life expectancy? A lot of research has been done in the attempt to answer that question. And we have enough evidence to provide an answer: social distance and how that distance is perceived by people, in addition to the lack of social cohesion that it produces, is at the root of the problem. This situation appears clearly when we compare the life expectancy of a poor person in the United States (who makes $12,000 a year) with the life expectancy of a middle-class person in Ghana. The poor person in the United States is likely to have more material resources than the middle-class person of Ghana (who makes the equivalent of $9,000). The U.S. resident may have a car, a TV set, a larger apartment and other amenities that the middle-class person in Ghana does not. As a matter of fact, if the world were considered a single society, then the poor in the United States would be a member of the worldwide middle class and the middle-class person of Ghana would be part of the worldwide poor—certainly poorer than the poor in the United States. And yet, I repeat, the poor citizen of the United States (although of the worldwide middle class) has a shorter life expectancy than the middle-class person (although of the worldwide poor) in Ghana (two years less, to be precise).
Why? The answer is simple. It is more difficult to be a poor person in the United States than a middle-class person in Ghana."
http://www.monthlyreview.org/0604navarro.htm