Populations: Important Regional & International Differences in Populations, in respect of age, sex, occupation, social class, ethnicity and other characteristics

Understanding populations over time

Whilst births, deaths and migrations form important building blocks for understanding populations, Omran^[1], in this theory of epidemiologic transition, described many other factors impacting on population change.  His theory focuses on the complex change in patterns of health and disease and the importance of socioeconomic, political and cultural determinants such as standards of living, hygiene and nutrition. Omran describes the decline of infectious diseases in western Europe, the improvement in health outcomes for women and infants, improved life expectancy and gradual increase in cancer and cardiovascular diseases.  Japan fits into the 'Accelerated Epidemiologic Transition Model' and developing countries fit into the 'Delayed Epidemiologic Transition Model'.

More than 30 years since his theory was first published, many regions are not fitting neatly into Omran's theory.  Many low and middle income countries are suffering the double burden of high mortality from infectious diseases as well as emerging epidemics of non-communicable diseases, particularly in urban areas.   Russia is experiencing extremely high levels of alcohol related mortality amongst working age men.  The increase in childhood obesity in the UK has led to the danger of children having, for the first time, a shorter life expectancy than their parents.

International differences in respect of mortality

To understand the impact of mortality on a population both numerator i.e. the number of deaths and the denominator, the population of interest, are needed.

Registration of cause of death exists in approximately 70 countries, so comparing death rates across countries needs to be done with caution.  In India and China sentinel surveillance systems cover some parts of the population.  In other developing and middle income countries, registration systems are poorly developed, and surveys are used. 

The Global burden of Disease Study^[2] undertook an extensive synthesis of all available data to give a worldwide set of mortality estimates by age, sex, region and cause.  By 2003, data on deaths were available from 115 out of 192 countries, although data were complete in only 64 countries.  In some African countries, coverage was less than 10%. and estimates were made using South African data.  For many countries we still do not have information on who dies from what.

Death certificates provide space for multiple causes.  Summary statistics, reporting a single cause, aim to identify the 'underlying cause of death'.  There are, however, a number of weaknesses, for example,:

• Even in western European countries, diagnosis is an inexact and open to disagreements. 

• It is hard to gauge trends in death rates over time as ICD versions change - although  bridging tables do exist.

International differences on a range of indicators

The 2002 World Health Report examined a range of risks to health. (http://www.who.int/whr/2002/en/index.html) [accessed 30/11/2007]. It found that among men, the total burden of disease in the European region for the year 2000 is largely attributable to the consumption of alcohol and tobacco.  It accounted for almost as many DALYS as the total disease burden of some regions such as central and south eastern Europe.  It is equivalent to 80% of the disease burden in western Europe.  Download the database to compare countries on mortality, morbidity, lifestyle and health care indicators http://www.euro.who.int/hfadb [accessed 30/11/2007].

International differences in life expectancy[3]

Figure 1 gives comparative HALE at birth for selected countries. Stark inequalities are evident. While Japan had the highest HALE, with an average of 75 years, Sierra Leone had an average HALE of just 28.55 years. In general HALE figures are highest in countries in the northern hemisphere and lowest in war-torn countries of sub-Saharan Africa. Within all of these countries there are also internal disparities between rich and poor.

Figure 1: Healthy Life Expectancy at birth selected countries, male and female 

International differences in life expectancy over time³

Global life expectancy improved significantly during the Twentieth Century, especially in developed countries. Life expectancy at birth in the UK was 47 years in 1901^[5]. At the end of the century it was 77.5 years, an increase of over 64 per cent[3]. These gains were due largely to the eradication and control of numerous infectious diseases and to advances in agricultural technologies such as chemical fertilisers.  These increases, however, have not been universal. Due to the effects of HIV/AIDS life expectancy has actually declined recently in many sub-Saharan African countries. Average life expectancy in sub-Saharan Africa is now 47 years, when it could have been 62 without AIDS^[4].  Similarly, since the break-up of the Soviet Union in 1989, male life expectancy in Russia has dropped by 6 years to from 65 years in 1989 to 59 in 2005. 

International differences in age structure[4]

Regional differences in respect of age

The rise in sexually transmitted infections is predominantly affecting younger people.  Indications of public health in the English regions: sexual health http://www.nepho.org.uk/index.php?c=1662 [accessed 30/11/2007].

Regional differences in ethnicity

Indications of public health in the English regions: ethnicity and health http://www.lho.org.uk/viewResource.aspx?id=9840 [accessed 30/11/2007].

Regional Differences in social class

Widening inequalities in obesity by social class - health profile of England
http://www.dh.gov.uk/dr_consum_dh/groups [accessed 30/11/2007].

Office of Population Censuses and Surveys (OPCS) longitudinal study identified a 1% sample of the 1971 Census and followed them until death.  This study confirmed the existence of inequalities in health and the importance of social determinants such as housing tenure.
http://www.statistics.gov.uk/about/data/methodology [accessed 30/11/2007].

The Whitehall cohort study of British civil servants found marked inequalities in health and mortality by employment grade http://eprints.gla.ac.uk/2659/ [accessed 30/11/2007]. 

Regional differences in life expectancy

Whilst life expectancy is increasing overall in England, there is a distinct 'north/south' divide for female life expectancy at birth. In all regions from the Midlands northwards, female life expectancy is significantly shorter than in the regions to the south. The difference is around one year of life. For men in the north, life expectancy at birth is around two years shorter than for men in the south^[5].

Differences exist within regions also - see slide 20 showing tube map and differences in life expectancy in London
http://www.lho.org.uk/viewResource.aspx?id=10941 [accessed 30/11/2007].

References

[1] Omran, AR  The Epidemiologic Transition: A Theory of the Epidemiology of Population Change.' Milbank Memorial Fund Quarterly 49 (Oct 1971): 509-538
[2] http://www.who.int/healthinfo/bodproject/en/index.html [accessed 30/11/2007].
[3]http://www.esrc.ac.uk/ESRCInfoCentre/facts [accessed 30/11/2007].
[4] United Nations Department of Economic and Social Affairs/Population Division 23 World Population Prospects: The 2004 Revision, Volume III: Analytical Report http://www.un.org/esa/population/publications [accessed 30/11/2007].
[5] Health profile of England, Department of Health, 2006
 http://www.dh.gov.uk/en/Publicationsandstatistics [accessed 30/11/2007].

© M Goodyear & N Malhotra 2007