12.1 The Socioeconomic Gradient, or Why Do Some People Get Sick and Others Do Not?

I. WHO GETS SICK? THE SOCIAL INEQUALITY OF DISEASE

Disease is not distributed evenly through the population. Certain groups of people get sick more often than do others. Some populations have more premature deaths than others. These trends are revealed in epidemiological research, the study of disease in populations. Through such studies, the connections between society and the individual become apparent. Such connections have important implications for personal health and for social policy. This article is about those connections.

The recognition of social causes for disease began in the last century. Virchou, credited as the founder of modern pathology, did pioneering research into causes of typhus epidemics in a region now a part of Poland. He identified connections between disease and poverty, work, and the organization of agriculture. Typhus, his report concluded, can be eliminated through ' . . . education, with its daughters, liberty and prosperity.' Virchou confirmed that epidemic has its origins in social conditions and that its elimination required social change.

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II. THE POWER OF MONEY

If you wish to have a long and healthy life, it is advisable to be wealthy. More specifically, try not to be born into poverty. In the United States, the poorer you are, the more likely you are to contract and succumb to heart disease, respiratory disorders, ulcers, rheumatoid diseases, psychiatric diseases or a number of types of cancer. Being sick of course, affects your money situation.

The number one cause of bankruptcy in the United States today is overwhelming medical expense. Sophie Tucker summed it up well when she said, "I've been poor and I've been rich. Rich is better."

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When the incidence of disease correlates in some way with money or status, social scientists call that the socioeconomic gradient. Why is there a socioeconomic gradient? It seems so unfair! It is tough enough to be short of money without being sick more often because of it. Fair or not, in matters of health, money does matter. How does money exert its influence on health?

• Differential access to health care. This one seems logical but there is a problem; in egalitarian Scandinavian countries with equal access to government subsidized health care, the gradient still exists. The well-to-do are still healthier than those who are without.
• The poor live amidst health risks. The poor are more likely to be alcoholics, obese, or smokers. Housing is more often located on gang war turf, near toxic dumps or smoke-belching factories.
• Education leads to better health. In fact, years of schooling correlates rather well with the degree of health. The better educated of society tend to be healthier.
• The stress of poverty makes people sick. When people are broke, they seem to be holding the ladder to success for others, not climbing it themselves. In economic downturns, they are the first to be laid off. They have the least control of their lives. The poor are least likely to have good health insurance. For good measure, the affluent remainder to society looks down on them, denying a basic human need: self respect.

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None of these alone is responsible for some groups being more sick than others. The cause of the socioeconomic gradient is in fact complex and subtle. A long running study in Great Britain offers crucial new insight into why some groups of people seem more likely to get sick than others. The famous Whitehall Study is the focus of our next section.

However, two further comments must be made about money and health.

• •The socioeconomic gradient seems to make an indelible mark on life. In a study of elderly nuns who have lived similar adult lives together for decades, their disease patterns and longevity correlate with their socioeconomic status in childhood. The lack of money in childhood left a lifelong scar on their lives.
• •Some diseases run counter to the gradient. The wealthy are more prone to autoimmune diseases including rheumatoid arthritis, multiple sclerosis, melanoma, and endometriosis. Some medical people are skeptical of these negative correlations. They say that these are artifacts of detection. The poor have so many problems that these go unreported.

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III. CORONARY HEART DISEASE IN BRITISH CIVIL SERVANTS.

The highly respected Whitehall study in Britain has followed thousands of British civil servants for more than two decades, accumulating an extensive array of information on each of the individuals in the study. The data is both person specific at any given time(cross sectional) and longitudinal (over a period of time). This approach offers important advantages over the many studies of status and health based only on group average data at a single point in time. The study is elegant in design and rigorous in its execution.

Why civil servants? The hierarchy of income and rank in the civil service is well defined. (My note: pay attention to that term hierarchy! It will have cross-species implications later.) Something else about the civil servants in this study is important: Their income, work history, and health are well documented.

Early on, Whitehall researchers found that the mortality among males aged forty to sixty-four was about three and a half times higher for clerical and manual grades, than it was for senior administrative grades. The correlation between status and health is alive and well in the Whitehall project. But that is only the beginning of the story.

There was an obvious gradient in mortality from top to bottom of the civil service hierarchy. Mortality increased as one goes down through even the professional and executive ranks.

None of these upper groups are impoverished or deprived. All are employed in office jobs with low risk in the physical environment. They are well paid compared with the general population. Yet, however, there is still a gradient among just the upper ranks.

A gradient in mortality is shown for a number of diseases or causes of death (but not all). Top people smoked less than folks at the bottom. People at the top who did smoke were less affected by it. People at the lower grades had higher cholesterol and blood pressure levels. Yet, when the effects of the triad of smoking/cholesterol/high blood pressure are factored in, the gradient yet remains.

The established coronary risk factors seem to account for less than half the social gradient. Something else powerfully influences health. The influence seems to be the hierarchy itself

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New results from the Whitehall study (July 1997) show that employees with little control over their working environment face a significantly higher risk of heart disease than those with authority to influence their job conditions. Several factors were considered related to employment grade; low social supports, hostility, sedentary lifestyle, and smoking. None of these factors, however, explained the gradient as well as does low control.

Data from a study of 7,372 men and women in the British civil service were tracked from 1985 to 1993. In the earlier Whitehall study started in the 1960s found those in low-status jobs had a significantly higher risk of heart disease. In general, their health was worse and they died sooner; they were more likely to smoke and less likely to exercise. Health problems were greater in spite of access to government subsidized health care.

In the new study, Marmot's team looked at the effect of smoking, inactivity, high blood pressure, and the feeling of lack of control. That lack of control proved to be the largest single factor in the increased incidence of coronary heart disease at the lowest ranks. The persons at the lowest civil service levels had a 50% greater chance of developing symptoms of coronary heart disease. Lack of control was felt by 8% at the top, but by 75% at the bottom.

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How do workplace conditions translate into cardiovascular disease? A variety of psychological and social stresses affect hormonal and immune-system functions that can ravage the lining of the arteries that nourish the heart. Low control is associated with higher plasma fibrinogen concentrations. Fibrinogen is a protein that binds blood cells together to form clots. Also, stress hormones increases can trigger higher levels of fibrinogen. They can raise the pulse and make the heart less flexible in responding to changing demand. Clearly, social environment has a biological effect.

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What are the implications? Illness in the workplace is to some extent a management issue. The way work is organized appears to make an important contribution to the link between socioeconomic status and heart attack risk. Greater sensitivity to the design of work environments may be an important way to reduce inequalities in health. Social organization influences individual health.

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IV. DOMINANCE HIERARCHIES IN PRIMATES

Hierarchies appear in other primate species besides humans. They provide a cross-species opportunity for examination of the effect of hierarchies on health.

Free ranging olive baboons in Kenya have been examined for the effect of dominance hierarchy in their lives. There is a significant difference between dominant and subordinate males in the functioning of their endocrine systems. In dominant males, the physiological responses to stress--the 'fight or flight' responses are turned off more rapidly after the stressful event is passed. In subordinate animals, there seems to be a break in the feedback loop and the stress response continues on after the stressful event is passed.

Top baboons thus cope with stress better than their subordinates who seem to be in a state of continuous anxiety. (My note: one my most difficult professors in dental school said repeatedly, 'some people give ulcers and some people get them.' Just thinking of that course as I write this evokes stress.)

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Whitehall researchers report that all ranks have similar levels of elevated blood pressure when at work. But the blood pressure of senior administrators drops much more when they go home. They seem to be better able to leave work problems at work. They can turn off the stress response when leaving work. Doesn't their physiological response parallel that of the baboons? .

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In a study of female macaque monkeys, the animals' response to high cholesterol diets was studied. The intent was to induce heart disease, and this indeed occurred. But a striking finding was that the degree of stenosis (narrowing) of the coronary arteries was nearly four times as severe among the low-status as among the high status monkeys. Prolonged stress can lead to injury to the arterial walls, and this in turn to clotting, atherosclerosis, and coronary heart disease.

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V. DOES HEALTH CARE MATTER?

There have been enormous changes in the extent and patterns of disease in Western society. In the early nineteenth century the infant mortality rate was very high, life was short (about 40 years), and epidemics were common. Infectious diseases were often fatal. At the turn of the century, the United States' annual death rate was 28 per thousand population. It is 9 per thousand at present. The cause of death was usually pneumonia, influenza, tuberculosis, typhoid fever or dysentery.

The disease rate and the death rate have changed. Fewer people die of infectious disease now than in the past. Chronic diseases such as heart disease, cancer, and stroke are now the major causes of death in the United States. Is the medical establishment due all the credit?

Infectious diseases such as measles, tuberculosis, scarlet fever, typhoid, and pneumonia were in long secular declines before vaccines or antibiotics became available. Social changes in the environment seem primarily responsible for those beneficial declines in disease. The most obvious of these are sanitation, improved housing and nutrition, and the general rise in the standard of living. Was some individual suffering prevented or cured? Of course! But, the introduction of specific medical services are generally not responsible for most of the modern decline in mortality.

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VI. HEALTH POLICY

This article ends with a discussion of policy and choice. The health care industry in America consumes close to 14% of the GDP and in 1997 exceeded a thousand billion dollars annually. This is some serious money. Further, health care is able to absorb any number of dollars thrown at it. If we have Medicare expanded to include persons younger than 65 or devise universal coverage for children, it is going to cost something more in addition to the numbers I've cited.

The policy question is this: IF we are committed to better health for more people, THEN how is that achieved? This article has introduced you to the 'socioeconomic gradient' and disease. Now, think about what we've covered in this article, and then consider the following: if your goal is to reduce coronary heart disease, what is the most economical way to improve the lot of the most people? Should it be a new hospital cardiac ward bristling with new technology, or should it be improved working conditions? Knowledge of the 'socioeconomic gradient' and social factors in disease has dollars and cents value if we can apply it to both personal and public policy decisions.

..... CJ'99

Resources

Conrad, P. and Kern, R. The Sociology of Health and Illness, 4th ed. New York: St. Martin's Press, 1994. (This book contains an excellent set of articles. Many thanks to Stephanie Shanks-Meile for loaning her copy to me.)

Evans, R., Barer, M., and Marmor, T. Why Are Some People Healthy and Others Not? New York: Aldine de Gruyter, 1994.

Marmot, M., Bosma, H., Hemingway, H., Brunner, E., and Stansfeld, S. "Contribution of job control and other risk factors to social variations in coronary heart disease incidence" The Lancet Vol 350: July 26, 1997 pp 235-239.

Sapolsky, R. "How the Other Half Heals" Discover. April, 1998 pp 46-52.