An introduction
Epidemiology matters: a new introduction to methodological foundations
Chapter 1
Epidemiology is the science of understanding the
causes and distribution of population health so that we
may intervene to prevent disease and promote health.
Epidemiology Matters – Chapter 1
2
Examples of questions
epidemiologists ask
 What is the incidence of myocardial infarctions between
2010-2020 among women born in 1950 in the United
States?
 What are the causes of myocardial infarctions in this
population?
 If we were to change population dietary habits, what
improvement in myocardial infarction incidence could we
affect?
Epidemiology Matters – Chapter 1
3
1. Evolution of epidemiology
2. Our approach to teaching epidemiology
3. Seven steps to conduct an epidemiologic study
4. Farrlandia
5. Summary
Epidemiology Matters – Chapter 1
4
1. Evolution of epidemiology
2. Our approach to teaching epidemiology
3. Seven steps to conduct an epidemiologic study
4. Farrlandia
5. Summary
Epidemiology Matters – Chapter 1
5
Evolution of epidemiology
 Epidemiology is a relatively new as a formal scientific
discipline
 Practice of conducting epidemiologic studies is not new;
‘counting’ health and disease goes back centuries
 Many of design and analytic techniques that we use
today arose in response to health concerns during 19th
and 20th century
Epidemiology Matters – Chapter 1
6
Epidemiology, a beginning
 John Graunt – 17th century - pioneered approaches to tabulating
population health and mortality in rates, ratios, and proportions
 William Farr – 18th and 19th century - developed more
sophisticated life table approaches to understanding the force
and burden of mortality
 John Snow – 19th century - used epidemiologic approaches to
understand London cholera epidemic; developed and applied
basic measures of disease frequency and occurrence
Epidemiology Matters – Chapter 1
7
Epidemiology history, continued
 19th century – focus on infectious disease
 20th century – high-income countries shifted
toward non-communicable diseases
 Mid 20th century – methods formalized (1970s)
 Late 20th century – Miettinen, Rothman, and
Greenland - modern epidemiology (1980s)
formalized central disciplinary principles
Epidemiology Matters – Chapter 1
8
Current conceptual movements
1.
Ecosocial perspective on population health – suggests policies,
institutions, and characteristics of context contribute to the
shaping of health
2.
Life course perspective – determinants of health are distributed
across the life course and even before conception
Therefore, epidemiology understands causes of population health
across levels of influence - from cells to society - and across life
course.
Epidemiology Matters – Chapter 1
9
An ecosocial framework
Social and Economic Policies
Institutions
Neighborhoods and Communities
Living Conditions
Social Relationships
Individual Risk Factors
``
Genetic/Constitutional
Factors
``
Pathophysiologic pathways
Individual/Population
Health
Kaplan, G. What’s wrong with social epidemiology, and how can we make it better? Epid Rev 2004; 26: 124-135
A lifecourse approach to health
production
Uauy, R. et al. Diet, nutrition, and the life-course approach to cancer prevention. J Nutr 2005; 135: 2934S-2945S
1. Evolution of epidemiology
2. Our approach to teaching epidemiology
3. Seven steps to conduct an epidemiologic
study
4. Farrlandia
5. Summary
Epidemiology Matters – Chapter 1
12
Our approach to teaching epidemiology
 We are interested in an epidemiology of consequence, an
epidemiology that can guide the improvement of the health of
population
 Therefore, we focus here on teaching underlying concepts that start
from understanding populations, and lead the learner through the
key steps to designing an epidemiologic study
 We will mention and adopt the labels that are used in many other
epidemiology textbooks (e.g., confounding) but only after we have
introduced the reader to the underlying concepts
Epidemiology Matters – Chapter 1
13
1. Evolution of epidemiology
2. Our approach to teaching epidemiology
3. Seven steps to conduct an epidemiologic study
4. Farrlandia
5. Summary
Epidemiology Matters – Chapter 1
14
Epidemiology of consequence, seven steps
1.
Define the population of interest
2.
Conceptualize and create measures of exposures and health
indicators
3.
Take a sample of the population
4.
Estimate measures of association between exposures and health
indicators of interest
5.
Rigorously evaluate whether the association observed suggests a
causal association
6.
Assess the evidence for causes working together
7.
Assess the extent to which the result matters, is externally valid,
to other populations
Epidemiology Matters – Chapter 1
15
Epidemiology of consequence, seven steps
Descriptive epidemiology

Step 1. Define the population of interest

Step 2. Conceptualize and create measures of exposures and health indicators

Step 3. Take a sample of the population

Step 4. Estimate measures of association between exposures and health indicators of
interest
Assessing for causal effect

Step 5. Rigorously evaluate whether the association observed suggests a causal association
Conceptualizing and testing for interactions

Step 6. Assess the evidence for causes working together

Step 7. Assess the extent to which the result matters (is externally valid) to other populations
Epidemiology Matters – Chapter 1
16
1. Evolution of epidemiology
2. Our approach to teaching epidemiology
3. Seven steps to conduct an epidemiologic study
4. Farrlandia
5. Summary
Epidemiology Matters – Chapter 1
17
Farrlandia
 Examples often based on hypothetical geographic area,
Farrlandia
 Inspired by William Farr, pioneering epidemiologist and
statistician
 Through use of Farrlandia examples, students will focus
on applying foundational concepts to populations
Epidemiology Matters – Chapter 1
18
1. Evolution of epidemiology
2. Our approach to teaching epidemiology
3. Seven steps to conduct an epidemiologic study
4. Farrlandia
5. Summary
Epidemiology Matters – Chapter 1
19
Summary
 This book aims to provide learners with a systematic
grounding in the theoretical underpinnings of epidemiology
with an awareness of the practical considerations that are
essential for public health professionals
 This text establishes a foundation by building on
methodological innovation and teaching of the previous
century, while adopting a novel approach to teaching
epidemiologic foundations
Epidemiology Matters – Chapter 1
20
epidemiologymatters.org
Epidemiology Matters – Chapter 1
21