Geography Reference
In-Depth Information
commonly referred to as the 'determinants of
health' and fall into four broad categories:
1
Human biological determinants,
encompassing
factors that are internal to the human body
(for example, genetic composition, ageing and
gender).
2
Environmental determinants,
encompassing
environmental factors that are external to the
human body. These factors can be further
classified according to the physical
environment (for example, climate and
altitude), the social environment (for example,
housing and population density), and the
biological environment (for example, the
presence and persistence of disease-causing
microorganisms).
3
Lifestyle determinants,
encompassing personal
behaviours that can threaten health (for
example, personal hygiene, smoking,
substance abuse and diet).
4
Health-care system determinants,
encompassing
the resources devoted to health care and
medicine in a population.
The epidemiological (health) transition
Environments, lifestyles and health-care systems
alter with the processes of social and economic
development. As development rarely (if ever)
progresses at an even rate in a given geographical
area, it follows that socio-spatial variations in
health are intrinsically dynamic phenomena. One
framework for analysing this dynamism is the
concept of epidemiological transition (Omran
1971) and the broader concept of health transition
(Caldwell
et al
. 1990). The concept of
epidemiological transition was widely publicised
by Abdel Omran in 1971 and since then has been
the subject of empirical examination in many
countries of both the developed and developing
world (Frenk
et al
. 1989; 1996; Phillips 1990; 1994;
Phillips andVerhasselt 1994). Indeed, such has been
the impact of the concept that the wider subject
area has spawned its own journal since 1991,
Health Transition Review.
In essence, the epidemiological transition
envisages a process by which the mortality profile
(and, by implication, the health profile) of a human
population progresses through three distinct stages:
Stage 1, a period with a preponderance of Old
World epidemics and pandemics of infection and
famine; Stage 2, a period of receding pandemics;
and Stage 3, a period in which chronic,
degenerative and human-induced ailments
predominate. Each stage is associated with a
decreasing death rate, a decreasing birth rate, an
increasing life expectancy and demographic
ageing. More recently, and for developed countries
at least, Olshansky and Ault (1986) have posited a
Stage 4 of the transition. This fourth stage is
associated with advances in the medical treatment
of chronic and degenerative diseases, thereby
giving rise to increased survivorship (but
potentially worsening overall health status) in
middle-aged and elderly populations.
While the linear model of epidemiological
transition provides a conceptual framework for
studying the evolution of mortality patterns in
particular, and health patterns more generally, it is
obviously a simplification of a complex reality. The
transition is widely affected in its timing and
Current thought on the aetiology of many
chronic, degenerative and mental illnesses has
implicated a range of human biological,
environmental and lifestyle factors in disease
expression (see Kiple 1993; McNally
et al
. 1998).
For example, factors implicated in the aetiology
of cardiovascular disease have included nervous
stress, hypertension, cigarette smoking, physical
inactivity, obesity, genetic predisposition and the
existence of other diseases such as diabetes
mellitus. It seems likely that some complex and,
perhaps individualised, combinations of
predisposing and precipitating factors ensure that
some people, groups and places experience higher
or lower rates of certain diseases. It is also apparent
that, even in countries with high-grade systems of
medical care, there may be spatial variations in the
efficacy of programmes aimed at the early
detection and successful treatment of life-
threatening illnesses (Expert Advisory Group on
Cancer 1995).
