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Epi Wit & Wisdom Articles
Epidemiology’s Limitations
Highlighted in Recent Press Accounts (1 of 6)
Discipline in “Catch-22”
Situation
Epidemiology is a weak science
because it produces conflicting results, and epidemiologists are
self-serving because they publish their findings even when they are
uncertain, according to recent press accounts published in Science
(July 14) and in the New York Times (October 11). While the statements
reflect valid criticisms of epidemiology, they can be criticized for
not presenting a more balanced picture of the field, according to
epidemiologists who spoke with the Epi Monitor.
The apparent trigger for this
negative press is the long series of contradictory findings reported
in the medical literature over the years which serve to confuse the
public. “By one day saying one thing, the next another, we are in
collusion to the confusion,” Harvard’s Charles Hennekens told the
Times, which was reporting on a one-day symposium on Science and
Journalism held at Boston University. He added, “epidemiology is a
crude and inexact science... we tend to overstate findings, either
because we want attention or more grant money.”
In the lengthy six-page article
appearing in Science, more than a dozen epidemiologists were
interviewed and quoted for an article entitled “Epidemiology Faces Its
Limits.”
The basic theme of the story is
that epidemiologists have identified all of the major determinants of
chronic diseases, but in searching for the remaining and more subtle
risks of disease, the discipline is not able to establish low levels
of risk with much certainty.
Epidemiologists: A Nuisance to
Society?
As a result,
epidemiology often produces contradictory findings which cause fear,
confusion and anxiety in the population. It’s a catch-22 situation
because epidemiology is the only discipline which can study humans in
situations of risk and, even when small, such risks can be important
from a public health point of view. Thus, besides being of great
potential benefit to society, epidemiology produces side-effects which
can detract from its positive contributions. There’s a trade-off. As
Dimitrios Trichopoulos told Science, “we are fast becoming a nuisance
to society. People don’t take us seriously anymore, and when they do
take us seriously, we may unintentionally do more harm than good.”
Trichopoulos was co-author of the study linking coffee drinking to
pancreatic cancer, a finding which has not been replicated, according
to Science.
To make matters worse, the news
accounts describe all of the stakeholders involved (medical journals,
the press, health institutions, the public and epidemiologists) as
having self-serving reasons for maintaining the status quo by
exaggerating or over-interpreting the significance of small risks.
No Solutions in Sight
According to Science, none of
the epidemiologists could offer any clear-cut and effective solutions
to the problem other than calling for more skepticism on the part of
the press and on the part of epidemiologists. This solution, at least
for epidemiologists, seems doomed to fail since many—if not
most—epidemiologists already consider skepticism as their trademark.
Epidemiologists speaking at Boston University did suggest releasing
reports to journalists weeks in advance rather than just a few days in
order to reduce some of the confusion, but this would not neutralize
the reasons that journalists may have for sensationalizing the
results.
Apparently finding fault with
the article, several of the epidemiologists interviewed by Science
co-authored a letter (September 8) to correct the impression their
remarks may have produced that “evidence based on epidemiology is not
usually credible.” They point out that the discipline has offered many
positive contributions, including the documentation of:
• the adverse effects of smoking
• the relation of overweight to
many diseases
• the benefits of increased
physical activity for cardiovascular disease
• the effects of many
occupational exposures such as benzene and asbestos
• the relation of exogenous
postmenopausal estrogens to cancer of the uterus
• the relation of sunlight to
all forms of skin cancer
• the relation of ionizing
radiation to many cancers
• the adverse effects of many
pharmacologic agents such as DES and thalidomide
• the protective effects of high
intake of fruits and vegetables against many cancers
A representative of the Society
for Epidemiologic Research told the Epi Monitor that while the SER
does not plan any response to the Science article, the Society is
planning to organize a symposium at the next annual meeting on the
issues raised by the account.
Published November 1995 v
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