|Socioeconomic Status and Health Inequalities||To Health Determinants page|
As with any biological characteristic, there is considerable variation in health status in any population. Some people die young; some suffer chronic disease or disability; others live to a ripe old age. It is not these differences per se that comprise the theme of inequalities in health. Instead, it is the finding that such contrasts do not occur at random. Differences in health can be analyzed by region, by race, by gender or age, and by indicators of socioeconomic status. All of these show systematic patterns in the distribution of health, both between and within societies, such that at birth not every person shares an equal chance of a long and healthy life.
Socioeconomic status (SES) refers to a person's position in society. This cannot be measured directly, so there are a number of possible indicators. SES may be expressed in terms of income, or level of education, type of occupation, accumulated wealth or the value of a person's house, etc. Whatever the indicator we use, there is an almost universal tendency for people in lower socioeconomic groups to die younger and to suffer more illness during their lifetime.
Data from Canada.
In the diagram below, income is used to represent SES. It has been grouped into 5 categories ('quintiles') running from poor to rich. The graph shows life expectancy at age 25 by income quintiles. This indicates the years of life remaining, on average, to people in each income category. The data were taken from a study of 2.735 million Canadians who were followed for 15 years after the 1991 Census, with deaths being recorded and linked back to the information on the census. ("The Canadian census mortality follow-up study, 1991 through 2001". Health Reports 2008; 19(3):25-43).
You will observe that, for males, people in the lowest income category will live on average to age 73 (25 + 48), while people in the richest income level can expect to live to age 80 (25 + 55): a discrepancy of 7 years. The gap is about 4 years for women.
The same study compared mortality across occupational groups.
For men, the risk of dying (after adjustment for age) is more than twice as high for those who are unemployed compared to professionals. People who were visible minorities actually have lower mortality rates than the white population, but mortality among Aboriginal peoples is 1.4 times the rate in the non-Aboriginal population. Interestingly, people who only speak French have a 15% higher mortality risk than Anglophones or bilingual people.
For women, those with no paid occupation have a 50% increased risk of dying; visible minorities again fare better than the white population; Aboriginal women are at 1.76 times the risk of mortality (i.e., close to twice); but unilingual French speaking women have a slightly lower chance of dying.
Data from outside Canada
The table below shows data from England and Wales summarizing years of potential life lost per thousand in the population. This statistic counts deaths, but also considers how young the person was when he died. In this instance the data refer to men aged 20 to 65, so a death occurring at age 40 would contribute 25 years of potential life lost.
Annual, age-adjusted rate of Years of Potential Life Lost per 1000. Men aged 20 - 64, England and Wales, 1971 to 1992
I (professional people)
III (skilled non-manual)
III (skilled manual)
IV (partly skilled)
(Figures from Blane and Drever, British Medical Journal 1998;317:255)
You can see a clear gradient across the occupational groups, but perhaps even more provocative is the finding that, although premature deaths are declining over time, the rate of improvement is also greatest among the socially advantaged, so the social inequality is actually increasing. The inequality ratios across the occupational groups rose from 2.1 in 1970-72 [103 to 48.7], to 3.3 in 1991-93.
For another illustration of the effect of income on mortality, click here.
Link to Educational level and health PPT show on SES and Infant Mortality in Canada
Comparisons between countries
Because of the differences between countries in wealth, in climate, and natural resources, it is not surprising that there are international differences in health. What is striking (and politically unacceptable) is the level of the disparities, and the fact that improvements in the world economic situation have not greatly diminished the health gap between rich and poor countries.
To illustrate the type of international disparities that exist, the table below presents statistics from eight countries.
Gross national product per capita U.S. $, 1997
Life expectancy (1999)
Infant mortality rate per 1,000 births (1996)
Sources: Economic information and infant mortality from the World Bank’s World development report, 1998/99. Oxford, OUP, 1998. Life expectancy data from the World Health Organization’s World health report, 2000
When infant mortality rates are graphed by gross national product, mortality declines steeply as GNP rises to about $5,000 (U.S.) per person per year, then declines more slowly until about $10,000 and remain low thereafter (figures for 1996). Although the GNP dollar values have changed, the essential pattern of this relationship has remained unaltered over the past 50 years.
More information may be found in a World Bank report which shows socioeconomic differentials in mortality in 44 countries for the year 2000.