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Epi Wit & Wisdom Articles
UNC Epidemiology Chairman Calls
For a New “Macro-Epidemiology”
Gives New Meaning to
Epidemiology as the Basic Science of Public Health
[Editor’s note: Several writers
have now weighed in with their view that epidemiology needs to take a
broader, more encompassing view of causal factors of disease. This
report on an article and interview with Carl Shy presents the case
very compellingly.]
Economists differentiate between
micro and macro economics. Soon you may be hearing a similar
distinction applied routinely to epidemiology if Carl Shy has his way.
Writing in the March 15th issue of the American Journal of
Epidemiology, the chairman of the Department of Epidemiology at the
UNC School of Public Health accuses academic epidemiology of failure
to serve as the basic science of public health. This it could do,
according to Shy, if epidemiology expanded the subject matter of its
investigations from an almost exclusive focus on individual risk
factors of disease to a focus on the determinants of health at the
population-level. If epidemiology became more preoccupied with such
determinants, it would then be best described as “macro-epidemiology.”
As such, Shy believes it would better serve the needs of public
health.
In an hour-long interview with
the Epi Monitor, Shy explained what triggered the article in the AJE.
Despite the comment by a colleague who has known him a long time and
says that “Carl Shy has always thought this way,” Shy himself denies
this and says his thinking on this topic only began 5 - 6 years ago.
It was “really stimulated” by a book entitled Why Are Some People
Healthy And Others Are Not? The Population Determinants of Disease by
Robert Evans and colleagues at the University of British Columbia. In
addition, he began thinking more deeply about the mission of public
health when he assumed the chairmanship of the Department of
Epidemiology at the UNC School of Public Health in 1993. Shy asked
himself, why is epidemiology considered the basic science of public
health? If it is, what exactly does public health need from
epidemiology? In reading the 1988 report on the “Future of Public
Health,” Shy was impressed by the statement on the mission of public
health as organized community effort to create the conditions in which
people can be healthy. If that is the mission of public health, and if
the functions which stem from this mission are the now famous core
functions of assessment, assurance, and policy development,
epidemiologists need to provide data which helps public health to do
these functions well. This must be done by identifying the
determinants of the differences in health at the population-level,
according to Shy, and not only at the individual level. Put another
way, Shy believes we should focus more on the underlying causes of
disease and less on the proximate causes of disease.
When challenged on this point by
being asked if the underlying causes are not just more difficult to
identify and more difficult to intervene on, Shy asks his own
question: Are the underlying causes really more difficult, or do we
only approach the more proximate causes associated with the
bio-medical model of disease because we are used to thinking from this
framework and we have well-developed methods associated with it? Shy
believes that there is an element of ecology in disease occurrence,
that is, that disease is a consequence of relationships and
epidemiologists should study those relationships at the community or
population-level as well as at the individual level.
He cited an example of the
shortcomings of the bio-medical perspective. Some are arguing for the
greater involvement of communities in research, says Shy, but the
bio-medical perspective does not tolerate this involvement. But if one
needs to get at factors at the community-level, then one needs more
than the bio- medical perspective. Epidemiology is not about methods,
it is about solving problems, agrees Shy, and it is about how
epidemiology can provide knowledge that helps solve large problems
such as teenage pregnancy and violence.
Shy says he is not asking
epidemiologists to become advocates. While epidemiologists have an
obligation to function as public health practitioners and there may be
an appropriate time and place for epidemiologists to advocate for
findings and for certain policies that are consistent with findings,
Shy is really arguing for epidemiologists to pursue a different kind
of knowledge, he says.
Other sources which Shy cited as
being influential in his thinking are the Leeds Declaration which was
issued following a meeting in the United Kingdom where participants
concluded that the appropriate knowledge base for public health action
called for:
1) More research on upstream
causes of disease (meaning an extension of the search for causes of
disease from the individual to the community and sociopolitical
system)
2) More community participation
(meaning a broadening of the methods of epidemiologic research to
include qualitative and participatory research methods)
3) More consideration of the
social context of disease (meaning integrating lay knowledge with
scientific knowledge to take account of the richness and complexity of
community life)
He also noted that what he is
saying is not different from what Nancy Kreiger at Harvard and Neal
Pearce at UNC have said in some recent papers they have published.
Shy’s views were challenged in
the AJE by Alexander Walker who argued that “epidemiologic research
that does not ultimately reach out to physical theories of causation
runs the risk of having no theoretical basis at all... There remain
enormous unexplained social class gradients in mortality and disease,
and epidem-iologists should seek the answers to these unexplained
gradients. But in drawing from outside disciplines we need to do so as
scientists, choosing theories that can be challenged and refuted.”
When asked what needs to happen
to move his ideas forward, Shy said he thinks more students with
backgrounds in population sciences and more people who are accustomed
to thinking at the macro-level need to be recruited into epidemiology.
In short, we need to put “population” into epidemiology for real.
Published May 1997 v
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