José Antonio Vergara
Just like other indicators of the health status of a community (such as infant mortality, self-perceived health and welfare, etc) life expectancy, or the length of life expected at birth, the worldwide highest and lowest values of which are in Japan (81.9 years) and in Sierra Leone (34 years), shows the existence of great inequalities in health between countries and also within individual societies. The usual tendency has been to explain these differences and changes in the epidemiological profile in terms of factors such as access to medical care and isolated risk factors such as genetic inheritance, age, behaviour and other individual characteristics (smoking, obesity, blood pressure, cholesterol level, etc).
However, in recent years the research area of population health has revealed that the striking variation between different populations, such as between developed and poor countries, is a result of the effect of the social environment (education, working conditions, social and economic relations, living conditions, social exclusion, etc) in which people develop.
This new perspective on the social determinants of health is not restricted to the realisation that the persistent, or even worsening, poverty in various regions of the world, which is a result of the lack of basic necessities such as clean water, food and vaccinations, means that in, for example, Sierra Leone the mortality rate of children under 5 years old is 316 per 1000 live births while in Japan it is just 5 per 1000. The emerging social epidemiology also emphasises that, besides the effect of infectious diseases, which continue to be of primary importance in poor countries, in other more developed societies with other causes of health loss such as non-infectious diseases (high blood pressure, cardiovascular disease, stroke, cancer), accidents and mental health problems (depression, drug and alcohol abuse, etc), the most important factor in determining community health is the economic inequality between social classes, and the greater this inequality the more destructive it is of social cohesion and solidarity, which in turn creates the collective conditions for loss of health (lack of trust in other people, isolation, stress, etc). The World Health Organisation has recently set up a high-level Commission on Social Determinants of Health to examine and propose public policies with a view to improving global health by striving for social justice, human rights and sustainable development.