Epid 600 Class 1 Intro To Epidemiology

EPID 600: Introduction to Epidemiology University of Michigan School of Public Health

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Course details Fall Term 2008 Lecture on Tuesdays 10:00am-11:30am Lecture is in SPHII Auditorium Discussion sections on Thursdays All students should be in a section at either 10:00am-11:30am OR 11:30am-1:00pm. Discussion sections are in SPH-II M1170 or M4332 or M4318 Discussion sections are mandatory

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Primary instructor Sandro Galea, MD, DrPH Center for Social Epidemiology and Population Health Department of Epidemiology University of Michigan 1214 S. University Ann Arbor, MI 48103 734.647.9741 [email protected]

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Malta

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Toronto

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Toronto Philippines Guatemala

PNG

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Geraldton

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Geraldton

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Somalia

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Boston

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New York

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My work Social and economic determinants of health, a focus on the macrosocial determinants of health; urban health Epidemiology of mental health and drug use Consequences of disasters and mass trauma URL: www.disasterresearch.org

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Graduate student instructors Lauren Wallner, MPH [email protected] Elsie Grace, MPH [email protected] Jennifer Smith, MPH [email protected]

All instructors are VERY available by email and by appointment when you need us

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Course objectives   To

discuss and define basic epidemiologic principles

  To

introduce concepts central to epidemiologic measurement

  To

compare and contrast different epidemiologic study designs and to consider the application of these study designs to different research questions

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discuss factors that guide the interpretation of epidemiologic studies

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discuss the role of epidemiology in public health and the interrelation between epidemiology, clinical research, and other disciplines in public health and medicine. 17

The point of the course   To

introduce epidemiology students to the key concepts and methods of epidemiology

  To

prepare students for further courses in epidemiology, particularly EPID 655 and EPID 601

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introduce students to and to familiarize students with epidemiologic writing in peer-reviewed journals

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Therefore, the implicit aims of this course   The

course will involve a combination of lectures and discussion groups

  There

will be about 10 assignments in the course; all assignments will involve epidemiologic computations and also will require the reading of a recent peer-reviewed epidemiologic paper.

  It

is an implicit goal of the course that by the time they finish the course all students will have familiarity with how to read and evaluate epidemiologic papers

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Course organization Section 1: Introduction to epidemiology, basic concepts and measures Section 2: Study design and analysis Section 3: Special topics in epidemiology

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Course grading Class participation (10%) Weekly assignments (25%) Mid-term exam (15%), take-home, due October 28, 2008 at 10am Epidemiologic paper critique (20%) due on November 25, 2008 at 10am Final exam (30%)

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Class participation (10%) Speak up in class and in discussion sections You can miss no more than 2 discussion sections Speak up!

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Structure of discussion sections 30’: review of material covered in any given week 30’: review of answers from preceding week’s assignment 30’: discussion of epidemiologic paper for following week’s assignment

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Assignments (25%) Assignments are key to success in this course All assignments are graded out of 30; all questions have equal weighting; some questions are harder than others Assignments are intentionally designed to be computationally intensive Most of the assignments are stand-alone questions A part of each assignment refers to a recently published epidemiologic paper Please read the whole paper before answering the assignment questions 25

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Epidemiologic paper critique (20%) A structured analysis and critique of an epidemiologic paper There will be four papers handed out and students will choose one of the four to critique The critique will be no longer than 2,500 words “How to critique an epidemiologic paper” will be formally discussed on October 28, 2008

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Exams; mid-term + final (15+30%) Open-book, open-resource, i.e., you can use whatever resources you want, except for friends and family; mid-term is take home, final is in-class Exams will mirror format of assignments; if you have done well on assignments you should have nothing to worry about Mid-term exam handed out on October 23, and is due October 28, 2008; it is strongly recommended that you spend 1 hour on the mid-term Final exam is on December 16, 2008 from 4-6pm. 29

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How did people typically do in this class?

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Number of students

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A-

B+

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C+

Letter grade

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So how do I do well in this course?   Attend all sessions, do all assignments   Carefully read all the papers, both attached to class and to the assignments   Do extra questions. There are many examples online. Best, you should be doing all questions in the textbook. Sample answers are at: http://www.us.oup.com/us/companion.websites/ 0195135547/chapter.questions/?view=usa

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So, should I be in this class? Epidemiology track students welcome All other students are welcome provided you are interested in being in a computationally challenging course that is intended as preparation for higherlevel epidemiology courses

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Academic conduct School of public health policy is that student conduct should be consistent with that of a professional person Academic misconduct includes plagiarism, cheating, fabrication, falsification, and aiding/abetting such acts Practically speaking—we expect that students will work together on assignments but ask that all students hand in their own individual answers Please be creative; there is no reason to hand in identical work to that of others

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The trouble with epidemiologists and the solutions for this course Use of different terminology Occasionally cantankerous adherence to one way of doing and speaking about things We will use a book by Rothman, the same author for the book used in EPID 601 There may be some inconsistencies between EPID 600 lectures and the book—for the purposes of this course, the material in the lectures should guide answers to assignments and exams 36

What is epidemiology?

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What is epidemiology? The study of the distribution of disease and the determinants of disease The study of the “causes” of disease The “science of public health”

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Operationally “Counting” the causes of morbidity and mortality Determining the variables that are associated with the causes of morbidity and mortality Identifying the factors that are “causes” and are potentially modifiable Guiding (and evaluating) interventions to improve health

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Definition of epidemiology Three Greek words epi = among demos = people logos = doctrine So, “the doctrine of what is among or happening to people” Note, this is shared Greek root with “epidemic” (from Greek epi upon + demos people) but not derived from “epidemic”

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Basic assumptions of epidemiology 1. 

Death and disability do not occur at random

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There are causal factors that can be identified through the systematic investigation of human populations

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Identifying these causal factors can lead to preventive intervention

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Epidemiology and populations Epidemiology is fundamentally concerned with populations Epidemiology concerns itself with measuring distribution of disease in populations and the factors associated with those distributions This has implications later on as we consider the nature of causation in epidemiology

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History of epidemiology (1) 5th century, BCE, Hippocrates suggests that the development of human disease might be related to the external as well as the personal environment of an individual 1662, John Gruant publishes “The nature and political observations made upon the bills of mortality”, analyzing the weekly births and deaths in London, and quantifying (for the first time) the patterns of disease in a population

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History of epidemiology (2) 1796, Edward Jenner took cowpox from a lesion on the hand of a dairy maid and inoculated an 8-year old “volunteer”, then exposed the child to smallpox 6 weeks later 1839, William Farr, a physician with responsibility for medical statistics in the Office of the Registrar General of England and Wales, sets up a system for routine collection of numbers and causes of death

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William Farr (1807-1883) “The fatality of every class of disease...is augmented in the concentrated city population... let the rejected vegetables, the offal of slaughtered animals, the filth produced in every way decay in the houses...and the atmosphere will be an active poison, which will destroy...5-7 percent of the inhabitants annually.”

Farr W. Letter to the Registrar General. First Annual Report of the Registrar General of

Births, Deaths, and Marriages in England. 1839; London, HMSO.

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Life expectancy, England and Wales, 1800-1900 Life expectancy (years)

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Public Health Act of 1848

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Bongaarts J, ed. Beyond Six Billion: Forecasting the World’s Population. 2000; National Academy Press, pg. 123.

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History of epidemiology (3) 1855, John Snow, a physician best known for his developments in anesthesiology, formulates and tests a hypothesis that drinking water supplied by the Southwark and Vauxhall Company increased the risk of cholera compared with water from the Lambeth company

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Cholera and John Snow Four cholera epidemics with over 100,000 deaths in London in the mid-nineteenth century “Miasma” and “Germ” theories John Snow published treatise in 1849 supporting germ theory and suggesting contaminated water as a means of transmission An 1854 cholera outbreak was shown to be associated with one of London’s two water companies

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Determinants of cholera 200,000 cesspools Manure sold to farms London expanded rapidly Maintenance revenue fell Cesspools in disrepair Calls for removal unheeded for many years 52

The Broad Street Pump John Snow removed pump handle in 1854 to stop the spread of cholera Academic folklore: “The birth of public health”

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The efficacy of medical interventions?

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History of epidemiology (4), the twentieth century During the first half of the twentieth century, the study of epidemiology was largely concerned with infectious diseases In the second half of the twentieth century, epidemiology was concerned with chronic diseases HIV/AIDS confuses the whole focus in the late 1980s Growing emphasis on the “proximal” and immediate causes of health and disease until recent (past decade) rediscovery of the “social” determinants of health

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Ten greatest public health achievements, US, 1900-1999 Vaccination Motor-vehicle safety Safer workplace Control of infectious disease Decline in deaths from coronary heart disease and stroke Safer and healthier foods Healthier mothers and babies Family planning Fluoridation of drinking water Recognition of tobacco use as a health hazard

MMW. April 02, 1999 / 48(12);241-243 . http://www.cdc.gov/MMWR/preview/mmwrhtml/00056796.htm

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A digression...Michigan’s role 1944, Thomas Francis, Jr, Chair of Epidemiology, develops Influenza vaccine for US army 1955, Salk polio vaccine trials (N~1,800,000) end declaring vaccine safe and effective 1985, Ken Warner’s study on health implications of tobacco consolidate federal taxation policy as smoking disincentive etc

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A metaphor

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Rich

Poor

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Leading causes of death in the US, 2005

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Leading causes of death in the US, 2005

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Leading causes of death in the US, 2005

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Leading causes of death in the US, 2005

65 Kung HC, Hoyert DL, Xu JQ, Murphy SL. Deaths: Final data for 2005. National vital statistics reports; vol 56 no 10. Hyattsville, MD: National Center for Health Statistics. 2008.

66 Kung HC, Hoyert DL, Xu JQ, Murphy SL. Deaths: Final data for 2005. National vital statistics reports; vol 56 no 10. Hyattsville, MD: National Center for Health Statistics. 2008.

67 Kung HC, Hoyert DL, Xu JQ, Murphy SL. Deaths: Final data for 2005. National vital statistics reports; vol 56 no 10. Hyattsville, MD: National Center for Health Statistics. 2008.

Leading causes of death?

McGinnis and Foege 1993

Mokdad AH, Marks JS, Stroup DF, Gerberding DL. Actual causes of death in the United States, 2000. JAMA. 2004;291(10):1238-45

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“Actual” causes of death?

McGinnis and Foege 1993

Mokdad AH, Marks JS, Stroup DF, Gerberding DL. Actual causes of death in the United States, 2000. JAMA. 2004;291(10):1238-45

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Leading causes of death, worldwide, 2001

World Health Organization Annual Report, 2002

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The usual epidemiologic approach 1. 

Identify a disease of interest

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Identify exposures of interest based on what is known about the disease (prior epidemiologic research, biology, laboratory studies)

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Examine statistical associations between exposures and disease

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Hold constant factors that may be “mixed up” in this measure of association

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Infer a causal association between exposure and disease on the individual level

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Recommend intervention

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Epidemiologic papers, papers, papers...  

This course aims to introduce all students to reading modern epidemiologic papers

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You will have papers to read every week for course assignments

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There are papers that are used in each lecture for examples (the orange slides)

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There is a final paper critique assignment

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Remember—this course is meant for epidemiology students, so learning how to read and analyze papers is critical

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All papers are on C-tools already...read away! 73

So, what does an epidemiologic paper look like?

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The empiric epidemiologic paper Introduction Methods Results Discussion

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Introduction What is the scope of the problem? e.g., obesity is a national emergency etc What do we know about the problem? e.g., changes in eating patterns have influenced obesity What do we not know about the problem? e.g., does neighborhood social cohesion influence eating patterns? What is the purpose of this paper? e.g., to assess the relation between neighborhood social cohesion and eating patterns 76

Methods Sample Location, time, population, data collection methods, IRB approval Variables Discuss each variable used in analysis Analysis Step-by-step analysis 77

Results Table 1 shows… Figure 1 shows... Table 2 shows… Table 3 shows…

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Discussion Summary of study results i.e., “This population-based study showed…” How this study builds on previous knowledge “This study is consistent with previous work…” “This study differs from previous work…” “Explanations for these findings…” Limitations Conclusions/implications “Notwithstanding these limitations…” “Implications of this work are…” 79