HSS4303B

IntroductionTo Epidemiology

Science of the Gods

Jan 7, 2010“Epidemiologic Approaches”

HSS4303B

• Mondays 8:30AM-10:AM• Thursdays 10:AM-11:30AM• DMS1150

• *No* formal tutorials scheduled for this class• But we may create some informal ones

Who We Be?

• Professor– Dr Raywat Deonandan– Templeton 111 x8377– ray@deonandan.com

• Teaching Assistant– Ms Erin Russell– Erin.leigh.russell@gmail.com

Please emailFor appointments

Currently, no regular office hours

Everything You Need To Know

classes.deonandan.com/hss4303

If you have a question about the class, please check the website before emailing us.

Marks, Marks, Marks

• Written assignment = 10%

• Midterm = 20%

• Poster = 25%

• Final exam = 45%

Written Assignment

• Abstract– Very brief– Test of your reading, research, writing abilities– Test of your ability to follow instructions– Instructions are already on the website– Worth 10%– Due 11:59pm on Jan 28

Midterm

• Currently scheduled for Feb 11 (though I might move it to after Reading Week… stay tuned)– All multiple choice!– Very similar to the one given to HSS4303A

Poster

• Your chance to play scientist!– Test your ability to collaborate, research,

summarize and present– Everyone will present on April 10• HSS4303A, HSS4303B and even the French section

– Instructions will be uploaded to website real soon– Worth 25%

Final Exam

• During Exam Period– Current plan is to combine HSS4303A and

HSS4303B and give both sections the same exam– This plan may change if the content diverges– All multiple choice– Sample questions will be uploaded to website– Worth 45%

Textbooks?

1. Medical Epidemiology 4th Edition, by Greenberg et al and published by McGraw Hills Publications. ($56.95 + tax at Agora Books)

2. Epidemiology, by Gordis L, published by Elsevier Sauders. ($60.11 + tax at Agora Books)

The following books are recommended but not required. In syllabus, readings refer to book #1.

The Rules of Raywat

1. If you don’t want to be here, don’t come-you are not marked on attendance-I’d rather you not come than to come and talk during

lectures

1. Don’t piss me off-I *will* find a way to make you pay for it

Lecture Slides

• Slides are provided as a courtesy• Be sure to take your own notes because one

day there might not be any slides (I’m tricky like that)

Important Dates

• Jan 28 – written assignments are due!• Feb 11 – in-class midterm!• Feb 17-20 – Reading Week!• Mar 11 – submit your poster topic!• Apr 10 – poster presentations!• April 15 on – Exam period

Homework

• Previous years have had a mandatory tutorial for working through computational problems together

• This year, you’ll be given more take-home assignments instead (will not be marked)

• We will try to arrange 1-2 optional tutorial sessions before exams to go over the problems

What Is Epidemiology?

• “The study of the distribution and determinants of disease or health status in a population”

– CDC

• The Science of the Gods!– R. Deonandan

The Origin of Epidemiology

Dr John Snow1854Used non-medical means to discover source of cholera outbreak

Figure 1-12 Photograph of John Snow. (From the Wellcome Historical Medical Museum and Library, London.)

Figure 1-13 A drop of Thames water, as depicted by Punch in 1850. (From Extracts from Appendix (A) to the Report of the General Board of Health on the Epidemic Cholera of 1848 and 1849, published by HMSO, London, 1850. Int J Epidemiol 31:900-907, 2002.)

Shoe leather epidemiology

Epidemiology Allowed “Miasmatic Theory” to be Displaced

• Miasmatic theory– Miasma was considered to be a poisonous vapor

or mist filled with particles from decomposed matter (miasmata) that caused illnesses. It was identifiable by its foul smell.

• Supplanted by “Germ theory”– Most diseases caused by an infectious agent

HSS4303: Introduction to epidemiology

Deaths from cholera and water theory

Water supply # of houses

Deaths from

cholera

Deaths per

10,000 houses

Southwark and Vauxhall Co

40,046 1,263 315

Lambeth Co 26,107 98 38

Other districts in London

256,423 1,422 56

Types of Epidemiologists

• Clinical Epidemiologist• Public Health Epidemiologist• Population Epidemiologist

The Face of Brilliance

Epidemiology In Pop Culture

Village of the Damned (1995)

Outbreak (1995)

Fringe (2009)

ReGenesis (2004)

Dr Deonandan?I think not!

Some Terminology

• Clinical research or mathematical relationships:– Variable that predicts/causes an outcome is

independent variable

• Epidemiological research:– Variable that may predict/cause an outcome is

exposure

Some Terminology

• Epidemiological research:– Exposures that increase or decrease the

likelihood of developing certain disorders, conditions or diseases are called risk factors

Eg, research has shown a strong statistical association between the exposure of smoking and the outcome of having lung cancer smoking is therefore a risk factor for lung cancer.

Descriptive Studies

• A true “descriptive study” is an example of “descriptive epidemiology”–Who –What–Where–When

Descriptive Study

• Who– Students

• What– Left handedness

• Where– This class

• When– Right now

Right now, 23% of students in this class are left handed

Qualitative vs. Quantitative

Descriptive vs. Analytic

Observational vs. Experimental

Case-controlCohortCross-sectional

InterventionsClinical trials

Who gets the disease?When do they get it?Where do they get it?

What Is An Experiment?

From the internet: “the act of conducting a controlled test or investigation”

For our purposes, an experiment differs from other kinds of investigations in that the researcher manipulates something.

EXPERIMENTAL STUDY

Historical Triumphs of Epidemiology

Smallpox

In 1975, two year old Rahima Banu contracted last known case of naturally-occurring variola major Smallpox. -Wikipedia

The global eradication of smallpox was certified, based on intense verification activities in countries, by a commission of eminent scientists on 9 December 1979 and subsequently endorsed by the World Health Assembly on 8 May 1980-“Resolution WHA33.3”

“You have erased from the calendar of human afflictions one of its greatest. Yours is the comfortable reflection that mankind can never forget that you have lived. Future nations will know by history only that the loathsome smallpox has existed.”

-Thomas Jefferson to Edward Jenner, 1806

– 400,000 people died each year in the late 18th century

– 1/3 of the survivors became blind– Survivors also developed immunity to smallpox– Efforts to prevent smallpox• Variolation

– Edward Jenner took interest in cowpox to find solutions in the prevention of smallpox

– WHO and eradication of smallpox• In 1967 WHO began the eradication program• 15 million people developed smallpox annually• 2 million people died• In 1980 smallpox was “eradicated”

Global eradication was possible because of…

Herd immunity

More Triumphs of Epidemiology

Before HIV was known to cause AIDS

• We knew it involved the “3 H’s”– Homosexuals– Haemophiliacs– Haitians

• Epidemiologists figured out:– It was bloodborne – It was probably a virus

Observational epidemiology

• Many a times we do not know the cause of disease but we can associate it with certain exposures– Streptococcal infection follows rheumatic fever and rheumatic heart

disease– Rheumatic fever is more frequent in army recruits than in school

children

• Lung cancer and smoking• Epidemiology based on observational data leads us to

understand the association between the morbidity and mortality from a disease and certain exposures, habits, lifestyle choices

Where Do Epidemiologists Work?

• Universities (ahem)• Government • Public health agencies• Drug companies• Hospitals (MDs)• Private companies

What Are Some Of The Things That Epidemiologists Do?

Breast and lung cancer mortality in Canada

20

25

30

35

1993 1994 1995 1996 1997

lung cancer breast cancer

Prevention and therapy

• Prevention is integral to public health and also to clinical practice

• In clinical practice therapy is used to prevent complications, disability and death

• Prevention in public health is primary prevention• Prevention in clinical practice is

– Secondary prevention (minimize disease complications)– Tertiary prevention (minimize disability)

• Epidemiology is the basis for effective prevention programs

Diagnostic tests: false positive and false negative tests are used to assess sensitivity and specificity

Disease prognosis and changes in therapeutic regimens

Disease surveillance• Monitoring the patterns of occurrence of a disease within a

population is referred to as _____________. • There are many potential benefits from the collection of

surveillance data:– (1) can help to identify the new outbreak of an illness, such as AIDS, – (2) can provide clues, by considering the population groups that are

most affected by the illness, to possible causes of the condition, – (3) can be used to suggest strategies to control or prevent the spread

of disease, – (4) can be used to measure the impact of disease prevention and

control efforts, and finally, – (5) can provide information on the burden of illness, data that are

necessary for determining health and medical service needs

Figure 1-14 Breast versus lung cancer mortality: white females versus black females, United States, 1973-1995, age-adjusted to 1970 standard. (From Ries LAG, Kosary CL, Hankey BF, Miller BA, Edwards BK [eds]: SEER Cancer Statistics Review, 1973-1995. Bethesda, MD, National Cancer Institute, 1998.)

Trend Analysis