Practice of Medicine
Quantitative Medicine:
Epidemiology & Biostatistics
Inde 201
POM Q1 (Fall quarter) 2015
September 28, 2015
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Objectives for today
 Introductions
 Epidemiology in medicine
 Course overview, review of the syllabus
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Course Instructor & TAs
Rita Popat, PhD (QM Topic Lead)
Clinical Associate Professor
Dept. of Health Research & Policy (HRP)
Division of Epidemiology
Justin Norden, M.Phil. (Course TA)
2nd yr medical student
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Introduction to epidemiology
 What is epidemiology?
 Why should you care?
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What is epidemiology?
 What does the word mean?
 From Greek: epi=upon + demos=people
 “upon the people”
 Epidemic: describes a disease that quickly and
severely affects lots of people and then subsides
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John Snow and the cholera epidemic
in the 1850s
1813-1858
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What is epidemiology?
“Epidemiology is the study of the distribution and
determinants of health-related states or events in
populations and the application of this study to control
health problems”
- Last JM
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Aims of Epidemiology
1. Determine risk factors of various diseases
2. Identify segments of the population with highest risk
to target prevention and intervention opportunities
3. Evaluate the effectiveness of health programs and
services in improving health of the population
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What does the array below represent?
1.
2.
3.
4.
5.
6.
High blood pressure
High blood cholesterol
Smoking
Obesity
Diabetes
Physical inactivity
Risk factors for cardiovascular disease
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“The concept of CVD risk factors has become an
integral part of the modern medical curriculum and
has led to the development of effective treatment
and preventive strategies in clinical practice.”
?
Acetylsalicylic acid
C9H8O4 [2-(acetyloxy)benzoic acid]
More than 50 million US adults take aspirin
regularly for long-term prevention of
cardiovascular disease, typically either
81 mg/d or 325 mg/d
Clinical Epidemiology
Clinical epidemiology is the application of epidemiologic
principles and methods to problems encountered in
clinical medicine.
- Fletcher RH, Fletcher SW, Wagner EH
In “Clinical Epidemiology: the essentials”
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Why should you care?
Methods in Quantitative medicine
relevant for other foundations of
medical care (population health,
EBP, nutrition, policy…)
Step 1 exam! OK, relevant…but
the reasons that really matter…
- Better advocate for your patient
- Better doctor
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Why should you care?
Epidemiology/clinical research informs all of the following:
 What diseases should you be looking for in patients?
 Which patients should you screen for disease?
 How are diseases diagnosed?
 What conditions cause the disease (risk factors)?
 How to prevent disease in your patients?
 How to treat diseases in your patients?
 What is disease prognosis?
 Public health policy/standard of practice.
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Why should you care?



Clinical issues in the practice of medicine
Clinical progression
Prognosis
X
Birth
X
Diagnosis
Susceptibility
Prevention
Screening and
diagnosis
X
Death
Treatment
Prognosis
Prevention of
complications
Why should you care?
Think about the patient interview you observed on Friday,
Sept. 25th
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Why should you care?
Epidemiology/clinical research informs all of the following:
 What diseases would you be looking for in this patient?
 How are diseases diagnosed?
 What conditions cause the disease (risk factors)?
 Which patients should you screen for disease?
 How to prevent disease in your patients?
 How to treat diseases in your patients?
 What is disease prognosis?
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Source:
http://www.health.gov.on.ca/english/pr
oviders/pub/cancer/psa/psa_guide/faq
.html
Randomize or Observe?
Outcome +
Open repair
Source
population
?
Outcome Outcome +
Endovascular
repair
Outcome TIME
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Observational vs. Experimental
Studies
 Experimental studies – the investigator tries to
control the environment in which the hypothesis is
tested (the randomized, double-blind clinical trial is
the gold standard)
 Observational studies – the population is
observed without any interference by the
investigator
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Why Observational Studies?





Cheaper
Faster
Can examine long-term effects
Hypothesis-generating
Sometimes, experimental studies are not ethical (e.g.,
randomizing subjects to smoke)
 Sometimes, experimental studies are not possible
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Cohort study: Basic design
Outcome +
Open repair
Outcome Source
population
Outcome +
Endovascular
repair
Outcome Endovascular vs Open Repair of Renal Artery Aneurysms: Outcomes of Repair and Long-Term Renal Function. J Am Coll
Surg 2013;217:263-269
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Studies of human subjects
Experiments
Observational
Descriptive
Case series
Cross-sectional
studies
Analytic
Ecologic
studies
Case-control
studies
Prospective
Randomized Clinical
Trials
Cohort
studies
Retrospective
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Experimental (Intervention) Studies
Strong
RCTs
Cohort studies
Case-control studies
Cross-sectional studies
Weak
Evidence for causality
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Epidemiology and medicine:
Why should you care?
 Keeping up with the medical
literature will make you a better
doctor
 You risk being misled if you aren’t
savvy to study design and statistics
 You have to understand risk in
order to help patients understand
risk
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“Ultimately, treatment decisions are made by patients, not
practitioners and not policy makers. Patients rely on
physicians and other health care professionals to deliver the
most amount of information possible about treatment risks
and benefits. Patients then can consider these issues in the
context of their own individual preferences. Policy makers
Should not interfere with this process unless the evidence
they use to mandate care is substantial.”
JAMA editorial (August 17, 2011—Vol 306, No. 7)
Summary: Applications of epidemiology to
medicine
 Disease surveillance
 Discovering causes
 Evaluating diagnostic tests
 Evaluating screening programs
 Determining the natural history of disease
 Finding prognostic factors
 Testing treatments
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Objectives for today!
 Introductions
 Epidemiology in medicine
 Course overview, survey, review of the syllabus.
33
Primary Course Objectives
 To understand the research methods needed to create
and synthesize a body of knowledge that can be applied
to patient care.
 To feel confident in interpreting and implementing
existing information related to diseases of humans,
patient care, and public health.
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Class survey!
 Please complete Qs 1 through 6 (resting pulse)
 Group assignment (if birthday is an odd number – 15 squats, if
birthday is an even number – 15 arm raises)
Redcap link:
You may open the survey in your web browser by clicking the
link below:
POM class survey 2015
If the link above does not work, try copying the link below into
your web browser:
https://redcap.stanford.edu/surveys/?s=F38J8HFEYC
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Course overview
 Blended course (motivations)
 9-modules: pre-recorded online series on
epidemiology and biostatistics
 3 small-group sessions
 Reading: Medical Epidemiology, Greenberg et.
al, (editions 2-4 are all acceptable)
 Quizzes
 Review sessions and Office hours
 Integrated POM final exam
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Course overview
 IMPORTANT: relevant materials and
information for QM can be found on the
homepage:
F15-INDE-201-01 Materials / Quantitative
Medicine: STUDENTS PLEASE USE THIS
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This is all you need to access QM materials
Interactions in Education: Reflections
Context
Lecture
Learner
Teacher
Blended
Content
Courtesy Dr. Kelley Skeff
Statistical concepts we will cover include…
 fundamental concepts of measurement





scales of measurement
distribution, central tendency, variability, probability
disease prevalence and incidence
health impact (eg, risk differences and ratios)
sensitivity, specificity, predictive values
 fundamental concepts of hypothesis testing and statistical inference
 confidence intervals
 statistical significance and Type I error
 statistical power and Type II error
 Use of statistical tests for different types of data (e.g., comparing
means, proportions).
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This is not a statistics course!
 If you want to learn more about research
methodology or statistics….
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Clinical Epidemiology*
Research methodology
Biostatistics
HRP 225**
Fall quarter
HRP 258**
Spring quarter
HRP 226
Winter quarter
HRP 259
Fall quarter
HRP 251
Spring
HRP 261
Winter quarter
HRP 262
Spring quarter
** core requirements for clinical research scholarly concentration
*http://med.stanford.edu/epidemiology/epiProgram_2006.pdf
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Course requirements
 Satisfactory completion of the quizzes and the
final exam
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Office hours
Rita Popat
Wednesday 1:30-2:20 pm
Location: LKSC 203/4
Tel: 650-498-5206
E-mail: rpopat@stanford.edu
PLEASE CONTACT US!
Justin Norden
Office hour: Tuesday 12:30-1:20 pm,
Location: LKSC Cafe
E-mail: jnorden@stanford.edu
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