Health Care Timeline Review the Topic Material, “Timeline for the History of Public Health and Epidemiology” to complete this assignment. Using this

Health Care Timeline
Review the Topic Material, “Timeline for the History of Public Health and Epidemiology” to complete this assignment. Using this resource as an example, create your own timeline in a Word document with significant dates that influenced and changed the health care delivery systems.

Your timeline should begin where the timeline in the topic material above ends (1988).
Your timeline should end with the most current and significant information that you can find. You are required to add a minimum of 10 significant dates to this timeline in order to receive a passing grade.
Provide a detailed description for each significant date and event you add to the timeline.

Use appropriate and scholarly sources in order to complete this assignment successfully, such as peer-reviewed literature and web sources that have .edu, .gov, and .org domain addresses. Wikipedia, and most .com sources are not considered to be of sufficient scholarly rigor.

Understanding the Fundamentals of
Epidemiology

an evolving text

___________

Victor J. Schoenbach, Ph.D.

with

Wayne D. Rosamond, Ph.D.

___________

Department of Epidemiology
School of Public Health

University of North Carolina at Chapel Hill

Fall 2000 Edition

1999, 2000 Victor J. Schoenbach

Unless otherwise indicated, the text and diagrams in this work belong to the copyright owner above.
For reprint permission (royalty-free for noncommercial use by nonprofit, accredited, educational

organizations), please write to:

Victor J. Schoenbach, Ph.D.

Department of Epidemiology

University of North Carolina

School of Public Health

Chapel Hill, NC 27599-7400 USA

[emailprotected]

Permission to reprint material copyrighted by others and used here by their permission must be
obtained directly from them.

August 1999, 2000

Chapel Hill, North Carolina

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Preface

Introductory epidemiology courses are often referred to as “methods” courses, and many students
come to them hoping to learn the methods that have made epidemiology so important. Certainly
methods are an essential aspect of the field, and this text covers the usual complement. But
especially for the newcomer, the critical need is to learn how epidemiologists think about health and
the factors that affect it, and how epidemiologists approach studying them. Very few methods are
unique to epidemiology. “Epidemiologic thinking” is its essence. Therefore, for me the central
objective of an introductory course has been to explain the concepts and perspectives of the field.

For nearly 20 years I have had the privilege of teaching the introductory epidemiology course for
epidemiology majors at the University of North Carolina School of Public Health and the special
pleasure that derives from teaching students who have sought epidemiology out rather than come to
learn it only as a school requirement. I have also had the honor of being entrusted by my colleagues
with the responsibility for introducing our students to epidemiologic concepts and methods.

Over the years I have written out extensive lecture notes, initially in response to requests from
course participants and subsequently to develop my own understanding. Not all course participants
have appreciated them, but I have received sufficient positive feedback and expressions of interest
from graduates who have gone on to teach their own epidemiology courses that I have decided to
recast them as an “evolving text”. I use the term “evolving” because I continue to clarify, develop,
refine, correct, and, I hope, improve.

Regarding it as an evolving text is also my excuse for the fact that the material is not ready for
formal publication. Moreover, unlike a published text, this volume does not claim to be
authoritative nor even thoroughly proofread. As an evolving work, its further development has
always taken priority over appearance and, it must be admitted, occasionally also over accuracy.*

Although the word processing is nearly all my own, the content is certainly not. Besides the
extensive development and exposition of epidemiologic concepts and methods from courses and
publications by others, I have had the good fortune to study with and learn from outstanding
epidemiologists and biostatisticians, among them the late John Cassel, Gerardo Heiss, Barbara
Hulka, Michel Ibrahim, Sherman James, Bert Kaplan, David Kleinbaum, Gary Koch, Lawrence
Kupper, Hal Morgenstern, Abdel Omran, the late Ralph Patrick, Dana Quade, David Savitz, Carl
Shy, the late Cecil Slome, H.A. Tyroler, and Edward Wagner.

*
Important errata, as I learn about them, are posted on a site on the World Wide Web (http://www.epidemiolog.net/).

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My thinking and this text have also greatly benefited from interactions with other colleagues and
teachers, co-instructors, teaching assistants, collaborators, associates, research staff, fellows, and
students. I must particularly acknowledge the assistance of Charles Poole, who has generously
shared his expertise with me through his advanced methods course and frequent consultations. He
has even made the ultimate sacrifice reading this text and sitting through my lectures! The content
(errors excepted!) and to some extent the exposition, therefore, represent the knowledge, ideas,
examples, and teaching skills of many people, to a much greater extent than the specific attributions,
citations and acknowledgements would indicate.

Acknowledgements are of greater interest to authors than to readers, and I ask your forgiveness for
including several more. I received my own introduction to epidemiology from the late John Cassel –
– intellectual pioneer, inspiring lecturer, and humanist — and Bert Kaplan — quintessential scholar,
supporter, and friend, whose colleagueship, breadth of knowledge, depth of wisdom, dedication to
the ideals of the academy, and personal warmth have enriched the lives of so many. I would also
like to express my gratitude to colleagues, staff, secretaries (especially Pat Taylor, Edna Mackinnon
Lennon, and Virginia Reid), students, administrators, and family for inspiration, stimulation,
feedback, opportunity, advice, guidance, commitment, counseling, assistance, support, affection, and
a good deal more.

Enjoy Epidemiology!

Victor J. Schoenbach

Chapel Hill, North Carolina

U.S.A.

August 17, 1999

Postscript: After the 20th anniversary edition of EPID 168 (“Fundamentals of epidemiology”), my
teaching responsibilities have changed to its sister course, EPID 160 (“Principles of epidemiology”).
EPID 160 serves as the basic introductory course for all students, graduate and undergraduate, who
are not majoring in epidemiology. Thus its audience is much more diverse in both interests and
preparation. Time will tell if I am able to continue to refine the Evolving Text, but if so it will begin
to move in the direction of making it more suitable for a general and international readership. I
have been gratified by the expressions of interest in it in its present form and hope that it will
continue to be of use to others.

March 9, 2001.

Table of Contents

Chapter (in Acrobat , click on a chapter name to move to that page) Page*

Preface……………………………………………………………………………………………………………………………… 1

1. Epidemiology Definition, functions, and characteristics ……………………………………………… 3

2. An evolving historical perspective ………………………………………………………………………………….. 17

3. Studying populations – basic demography ………………………………………………………………………. 31
Assignment ……………………………………………………………………………………… 53
Solutions …………………………………………………………………………………………. 57

4. The Phenomenon of Disease …………………………………………………………………………………………. 59

5. Measuring Disease and Exposure …………………………………………………………………………………… 81
Appendix on weighted averages…………………………………………………….. 113
Appendix on logarithms ………………………………………………………………… 115
Assignment ……………………………………………………………………………………. 117
Solutions ……………………………………………………………………………………….. 123

6. Standardization of rates and ratios…………………………………………………………………………………129
Assignment ……………………………………………………………………………………. 149
Solutions ……………………………………………………………………………………….. 153

7. Relating risk factors……………………………………………………………………………………………………….161
Appendix……………………………………………………………………………………….. 199
Assignment ……………………………………………………………………………………. 201
Solutions ……………………………………………………………………………………….. 205

8. Analytic study designs……………………………………………………………………………………………………209
Assignment ……………………………………………………………………………………. 257
Solutions ……………………………………………………………………………………….. 265

9. Causal inference …………………………………………………………………………………………………………….269

10. Sources of error …………………………………………………………………………………………………………….287
Appendices ……………………………………………………………………………………. 319
Assignment ……………………………………………………………………………………. 325
Solutions ……………………………………………………………………………………….. 329

www.epidemiolog.net/ Victor J. Schoenbach Table of contents
8/2/1001

11. Multicausality Confounding …………………………………………………………………………………….. 335
Assignment ……………………………………………………………………………………. 373
Solutions ……………………………………………………………………………………….. 377

12. Multicausality Effect modification …………………………………………………………………………… 381
Assignment ……………………………………………………………………………………. 413
Solutions ……………………………………………………………………………………….. 417

13. Multicausality Analysis approaches ………………………………………………………………………….. 423
Assignment (see next chapter)

14. Data analysis and interpretation ……………………………………………………………………………………. 451
Assignment ……………………………………………………………………………………. 499
Solutions ……………………………………………………………………………………….. 503

15. Practical aspects of epidemiologic research…………………………………………………………………… 507

16. Data management and data analysis ……………………………………………………………………………… 523

17. Epidemiology and public health……………………………………………………………………………………. 551

18. Overview and Conclusion…………………………………………………………………………………………….. 565

* Note: page numbers do not exactly match the number of the physical page because of
unnumbered pages and are not in exact sequence because of chapter revisions or pages inserted
from other sources (e.g., published articles for assignments).

Index: although no index is available, the Acrobat Reader has powerful search capabilities (see
the Edit Menu). You can search through all chapters at once by viewing the PDF that contains all
of the chapters and assignments in a single document.

Other epidemiology learning materials and resources, including practice examinations, may be found
at www.epidemiolog.net

http://www.epidemiolog.net/

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1. Epidemiology Definition, functions, and characteristics

Definition, characteristics, uses, varieties, and key aspects of epidemiology*

What to tell your family and friends
When your family or friends ask what you are studying, and you say epidemiology, the response is
often something like:

Youre studying what?
Does that have something to do with skin?

Uh-huh. And what else are you studying?
How should you reply? One possibility is to give a formal definition (e.g., The study of the
distribution and determinants of health related states and events in populations, and the application
of this study to control health problems [John M. Last, Dictionary of Epidemiology]). Another possible
reply is, Well, some epidemiologists study the skin. But epidemiologists study all kinds of diseases
and other aspects of health, also. The root word is epidemic, rather than epidermis. Another
reply could be. Epidemiology is the study of health and disease in populations. Its a basic science
of public health., though then be prepared to define public health. And, if youre feeling erudite,
you can follow-up with, Epidemiology comes from the Greek epi (among, upon), demos (people),
and logy (study).

Epidemiology in transition?

The above should satisfy your friends, but what about yourself? Particularly if you are entering on
the pathway to becoming an epidemiologist, do you know where it will lead you? According to
Thomas Kuhn (1970:136-7), textbooks address themselves to an already articulated body of
problems, data, and theory, most often to the particular set of paradigms to which the scientific
community is committed at the time they are written.[They] record the stable outcome of past
revolutions and thus display the bases of the current normal-scientific tradition. Raj Bhopals
review (1997), however, reports that recent epidemiology texts present a diversity of concepts and
information, even in regard to the building blocks of epidemiology. Bhopal sees the fundamental
question as whether epidemiology is primarily an applied public health disciplineor primarily a
science in which methods and theory dominate over practice and application. He predicts a lively
discussion that will sharpen in the 21st century.

Indeed, in the leading commentary in the August 1999 issue of the American Journal of Public Health,
three of my colleagues including our department chair seek to differentiate between epidemiology (a
science) and public health (a mission). They argue that the second half of Lasts definition

* Dr. Raymond Greenberg wrote the original versions of the chapter subtitles.

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(application and control) describes the broader enterprise of public health rather than
epidemiology. Epidemiology contributes to the rationale for public health policies and services and
is important for use in their evaluation, but the delivery of those services or the implementation of
those policies is not part of epidemiology (Savitz et al., 1999: 1158-1159). Further, the product
of research is information, not, as has been argued, public health action and implementation
(Atwood et al., 1997: 693). (Savitz et al.: 1160).

The article by David Savitz, Charles Poole, and William Miller might be regarded in part as a
response to the charge made in an article by our previous chair, Carl Shy, that academic
epidemiology has failed to develop the scientific methods and the knowledge base to support the
fundamental public health mission of preventing disease and promoting health through organized
community efforts (Shy, 1997). In making this charge, Shy builds on the contention in the Institute
of Medicine report on The Future of Public Health (Committee for the Study of the Future of Public
Health, 1988, which asserted that the U.S. public health system was in disarray) that schools of
public health are too divorced from public health practice. In that vein, in the editorial that precedes
the Savitz et al. commentary, the previous Director of the Centers for Disease Control and
Prevention (CDC) and two of his colleagues assert that, [Epidemiologists] can make their goal
journal publication, public interpretation of findings, or public health interventions, adding that
epidemiologys full value is achieved only when its contributions are placed in the context of public
health action, resulting in a healthier populace. (Koplan et al., 1999).

These contrasting positions are not necessarily in conflict. To say that public health action is
required to achieve epidemiologys full value does not imply that epidemiology or epidemiologists
must launch that public health action, nor does appreciation of epidemiologists contributions imply
that those contributions are epidemiology (as opposed to good works that happen to be done by
epidemiologists). But others have explicitly endorsed a diversity of roles for epidemiology. In a
2002 article, Douglas Weed and Pamela Mink provide a succinct and thoughtful discussion of this
twenty-year long remarkable disciplinary rift, concluding that Science and policy walk hand-in-
hand under the umbrella of epidemiology. (Weed and Mink, 2002: 70). They add that an
epidemiologist can be a full-fledged epidemiologist whether s/he does etiologic research alone,
combines public health practice and policymaking with research, or spends most of her/his time
making the public health system work. Perhaps influenced by the terrorism attacks of the
previous autumn, the ensuing upsurge of concern about preparedness, and Internet dissemination of
health information of highly variable reliability, Richard Kaslow in his 2002 Presidential Address to
the American College of Epidemiology placed advocacy squarely within the epidemiology
profession: Individual epidemiologists may decline to get involved, but I do not believe
epidemiology without advocacy is any longer a viable option for the profession collectively. Through
the College, our profession can speak with a compelling voice. It is no longer enough to serve the
public simply by producing credible data, we must effectively translate those data into clear and
balanced messages. (Kaslow, 2003: 547).

But whether we see ourselves first as scientists or first as public health professionals, our work takes
place in a societal context, with resources and therefore priorities assigned by political and economic
institutions that appear to serve the interests of some people and groups more than of others
(Winkelstein, 2000). The research we do and our behavior in our other professional activities

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inevitably reflect our backgrounds and life experiences, our values and preconceptions, our personal
ambitions and responsibilities. In that sense, what is epidemiology and what is not, and who is an
epidemiologist and who is not, are determined in part by the custodians of curricula, hiring, research
funding, and publication. Thus, you have an opportunity to make epidemiology what you think it
should be. You may also acquire a responsibility:

Do epidemiologists and other public health professionals have a responsibility to
ask whether the ways we think and work reflect or contribute to social inequality?
Proponents of socially responsible science would answer yes. What say you?

(Krieger, 1999: 1152)

Asking the right questions is fundamental, but you may also need to help develop the methods to
enable epidemiologists to do what you think we should. In recent decades there have been great
strides in the development and teaching of epidemiologic concepts and methods to study health
problems of the individuals in a population, but these concepts and methods are less adequate for
understanding population health (Koopman and Lynch, 1999), even in regard to epidemics the
origin of our discipline and its name. Indeed, Ollie Miettinen, a key thinker in defining the
conceptual basis of modern epidemiology, does not even regard the occurrence of epidemics, a
focal concern of classical epidemiology, as a problem of the form characteristic of modern
epidemiologic research, because an epidemic is an affliction of a population in the aggregate, rather
than of its individuals (Miettinen, 1985:4). For Miettinen, the discipline of epidemiology is the
aggregate of principles of studying the occurrence of illness and related states and events. (Miettinen,
1985:4).

Advances in the methods for the study of health and disease in populations epidemiologys calling
card, as it were may ease some of the apparent conflict between those who see epidemiology first
as a scientific enterprise and those who see it foremost as a vehicle for solving major public health
problems (Schwartz and Carpenter, 1999). Independent of whether epidemiologists are willing to
study problems that cannot be solved within the prevailing paradigm and the conceptual and
instrumental tools that it supplies (Kuhn, 1970), understanding those problems will require effective
concepts and methods. Warren Winkelstein (2000) sees the need for a more expansionist
approach in order to address disease problems arising from pollution, global warming, population
growth, poverty, social inequality, civil unrest, and violence. Even without taking the further step of
proposing that epidemiology should attempt to reduce these conditions themselves, the challenges
for epidemiology are daunting.

Epidemiology functions and areas of application

The perspective in this text is that epidemiology is both a field of research to advance scientific
understanding and also of application of knowledge to control disease and advance public health, a
(primarily observational) science and a public health profession. Thus, epidemiologists conduct
research and also work to control and prevent disease; they are scientists and engineers.
Epidemiologic investigation is problem-oriented and tends toward applied research. Although it has
a growing body of theory, the field is primarily empirically driven. Partly for these reasons,
epidemiologists draw freely from other fields and gravitate towards multidisciplinary approaches.

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Milton Terris, a leading exponent of close interrelationships among epidemiology, public health, and
policy, has summarized the functions of epidemiology as:

1. Discover the agent, host, and environmental factors that affect health, in order to provide the
scientific basis for the prevention of disease and injury and the promotion of health.

2. Determine the relative importance of causes of illness, disability, and death, in order to
establish priorities for research and action.

3. Identify those sections of the population which have the greatest risk from specific causes of
ill health [and benefit from specific interventions], in order that the indicated action may be
directed appropriately. (targeting)

4. Evaluate the effectiveness of preventive and therapeutic health programs and services in
improving the health of the population.

(Milton Terris, The Society for Epidemiologic Research (SER) and the future of
epidemiology. Am J Epidemiol 1992; 136(8):909-915, p 912)

To these might be added:

5. Study the natural history of disease from its precursor states through its manifestations and
clinical course

6. Conduct surveillance of disease and injury occurrence in populations and of the levels of risk
factors passive (receive reports), active (poll practitioners, conduct surveys)

7. Investigate outbreaks (e.g., hospital-acquired infections, disease clusters, food-borne and
water-borne infections) to identify their source and controlling epidemics (e.g., measles,
rubella, coronary heart disease, overweight)

Classic and recent examples of epidemiologic investigation

Epidemiology has made significant contributions to the understanding and control of many health-
related conditions, and epidemiologists are actively involved in studying many others. Some of the
classic investigations and some areas of recent and current attention are listed below:

Scurvy (James Lind) – intervention trial, nutritional deficiency

Scrotal cancer (Percival Pott) – occupational health, carcinogens

Measles (Peter Panum) – incubation period, infectious period

Cholera (John Snow) – waterborne transmission, natural experiment

Puerperal fever (Ignatius Semmelweis) – hygienic prevention

Pellagra (Joseph Goldberger) – epidemic disease was not communicable

Rubella and congenital birth defects (Gregg) – prenatal exposure

Retrolental fibroplasia – iatrogenic disease

Lung cancer and smoking – coming of age of chronic disease epidemiology

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Fluoride and dental caries – community epidemiology; environmental prevention

Poliomyelitis immunization trial – a massive experiment that demonstrated the effectiveness of
the vaccine against this greatly feared virus

Cardiovascular disease – longitudinal community studies; community intervention trials

Breast cancer screening a large-scale randomized trial of effectiveness of cancer early detection
through screening

Reyes syndrome and aspirin – an epidemiologic success involving a rare but devastating disease
brought on by a familiar and ubiquitous medicine

Toxic shock syndrome – an epidemiologic success in a point-source epidemic resulting from a
new product introduction

Estrogens and endometrial cancer – controversies of case-control methodology and bias;
pharmacoepidemiology

Psychiatric disorder – challenges in disease classification and assessment

Lead and cognitive development – a crucial role for a biologic marker

Electromagnetic fields – can an exposure be exonerated?

Legionnaires disease – a newly recognized pathogenic bacterium foreshadows the resurgence of
infectious diseases as a public health challenge in the U.S.

HIV – a new or newly-recognized virus that has transformed the public health and epidemiology
landscape with respect to infectious diseases in general and sexually-transmitted infections
specifically

Tuberculosis – reminding epidemiology of its roots; control of a pathogen is very different from
its eradication

Injury – epidemiology without disease

Homicide – a behavioral epidemic or an environmental plague?

Varieties of epidemiology

As epidemiology continues to develop and to expand into new areas, the field has diversified into
many forms:

Surveillance, shoe-leather epidemiology (outbreak investigations), and epidemic control

Microbial epidemiology biology and ecology of pathogenic microorganisms, their lifecycles,
and their interactions with their human and non-human hosts

Descriptive epidemiology examination of patterns of occurrence of disease and injury and
their determinants

Risk factor epidemiology searching for exposure-disease associations that may provide
insights into etiology and avenues for prevention

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Clinical epidemiology* and the evaluation of healthcare assess accuracy, efficacy, effectiveness,
and unintended consequences of methods of prevention, early detection, diagnosis,
treatment, and management of health conditions

Molecular epidemiology investigate disease at the molecular level to precisely characterize
pathological processes and exposures, to elucidate mechanisms of pathogenesis, and to
identify precursor conditions

Genetic epidemiology the confluence of molecular biology, population studies, and statistical
models with an emphasis on heritable influences on disease susceptibility and expression

Big Epidemiology** multisite collaborative trials, such as the Hypertension Detection and
Follow-up Program (HDFP), Coronary Primary Prevention Trial (CPPT), Multiple Risk
Factor Intervention Trial (MRFIT), Womens Health Initiative (WHI)

Entrepreneurial epidemiology building institutions and careers by winning research funding
and facilities

Testimonial epidemiology giving depositions and testifying in court or in legislative hearings
on the state of epidemiologic evidence on a matter of dispute

Social epidemiology interpersonal and community-level factors influencing health at the
population level

Global epidemiology assessing the effects of human activity on the ecosystem that supports
life on Earth.

Characteristics of epidemiology

With so many varieties of epidemiology, it is no wonder that confusion abounds about what is and
what is not epidemiology. Epidemiologic research tends to:

be observational, rather than experimental;

* In David Sackett et al.’s Clinical Epidemiology, 2nd ed, it is recounted that when one of the authors
(P.T.), then a medical student in England sought career guidance from a world-renowned London
epidemiologist, he was informed that it was amoral to combine epidemiology with clinical
practice!

** “Big” in epidemiology might be defined as upwards of $100 million for a study. To put these
studies in perspective, the Human Genome Project cost $250 million in public funds, CERN (high
energy particle physics research in Switzerland) $638 million/year, the Hubble Space Telescope $3
billion, and the Apollo Program $115 billion. (1999 dollars; data from the National Institutes of
Health, the European Space Agency, and NASA, by way of Hannah Fairfield in the New York Times
(Science Times, 6/27/2000).

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