Epidemiology and public health
! EXAM: don’t need to study the applied examples of guest lectures
H1 Introduction to epidemiology and public health
1.1 Epidemiology and public health
What is epidemiology?
Core idea
Epidemiology is consistently defined as:
“A method of reasoning about disease that deals with biological inference derived from observations of
disease phenomena in population groups.”
“The study of the occurrence of illness.”
WHO: “The study of the distribution and determinants of health-related states or events, and the
application of this study to control health problems.”
Purpose: epidemiologic research aims to fill knowledge gaps and ultimately improve public health
How epidemiology works
▪ Main method: counting within groups and comparing between groups
▪ Main challenges:
o Who to count? → defining the study population
o When to count? → timing, follow-up
o How to compare? → appropriate measures, valid contrasts
What questions does epidemiology answer?:
1. What is the burden of disease?
2. What is the prognosis of a disease?
3. Which risk factors/exposures cause disease?
Types of epidemiology
1. Descriptive epidemiology
a. Non-causal analyses which describe observed data (e.g. surveillance) Descriptive
b. Crucial foundation for analytic work!
2. Predictive (prognostic) epidemiology
a. Uses observed data to make statements or predictions about disease course
(e.g. used in clinical epidemiology)
Analytical
3. Causal (etiologic) epidemiology
a. Causal effects of risk factors/exposures on disease
i. Studies whether exposures cause disease
! Epidemiology is a multidisciplinary field that fits to the public health interest
Surveillance
Defined as the ongoing, systematic collection, analysis, interpretation, and dissemination of health-related data
Essential for:
Detecting changes in disease epidemiology
1
, Estimating incidence and burden
Monitoring prevention programs
Supporting public health authorities
Predicting spread
Example: Sciensano’s EPISTAT surveillance systems
What is public health?
Definitions
WHO: “The art and science of preventing disease, prolonging life and promoting health through the
organized efforts of society.”
Rothman: “The community effort to protect, maintain, and improve population health through organized
means.”
Role of public health
Public health activities include:
▪ Establishing health objectives and priorities
▪ Health promotion
▪ Disease prevention
▪ Health protection
▪ Health services
Approach of public health
A stepwise logic:
1. What is the problem? → Surveillance
2. What is the cause? → Risk factor identification
3. What works? → Intervention evaluation
4. How do we implement it? → Implementation science
Purpose of epidemiology in public health practice
Epidemiology helps to:
Discover the agent, host, and environmental factors that affect health
Determine the relative importance of causes of illness, disability and death
Identify those segments of the population that have the greatest risk from specific causes of ill health
Evaluate the effectiveness of health programs and services in improving population health
Applications of epidemiology in public health domains
1. Surveillance
a. Descriptive epidemiology used to set priorities and detect trends
2. Health services
a. Epidemiology evaluates:
i. Quality of care
ii. Need for more GPs
iii. Hospital practices (e.g., preventing antimicrobial resistance)
iv. Diagnostic test performance
3. Disease prevention
a. Primary prevention
i. Prevent disease before it occurs
ii. Examples: vaccination, mosquito nets, lifestyle changes
b. Secondary prevention
2
, i. Detect disease early, before symptoms
ii. Examples: mammography, blood pressure screening
c. Tertiary prevention
i. Manage disease after diagnosis to prevent complications
ii. Examples: rehab, chronic disease management, palliative care
4. Health promotion
a. Empowering people to improve their health
b. Examples: active transport, health literacy, healthy cities
5. Health protection
a. Minimizing exposure to hazards (e.g., water contamination, toxins)
b. Epidemiology provides evidence for identifying risks and evaluating interventions
1.2 History
Pioneers of epidemiology and public health
Hippocrates
▪ Greek physician and philosopher
▪ Diseases demonic possession and divine displeasure
▪ To physicians: Disease occurrence can be related to environment
▪ Earthly causes: “On Airs, Waters and Places”, at community of origin
▪ Behavior: “fond of drinking and eating to excess…”
▪ Change from mysticism towards observation and reason as causes of disease
Avicenna
▪ Persian philosopher, scientist and physician
▪ Empirical evidence and disease causation: experimentation and quantification
▪ One of the first ones to say that infectious diseases (ID) could be spread by contagion
o Quarantine to limit the spread of ID
Fracastoro
▪ Italian physician and poet
▪ Postulates some theories about how diseases spread
o Direct person-to-person contact
o Indirect contact
o Transmission at a distant (air or water)
▪ Also stated that health is affected by atmospheric conditions
John Graunt
▪ British
▪ World’s first epidemiologist and demographer
o Among the first to work on data
Bernadino Ramazzini
▪ Italien physician
▪ Occupational medicine
o Risks related to dozens of occupational hazards
o Review of suggestions for prevention and treatment
William Farr
3
, ▪ British
▪ Continued the work of Graunt
John Snow
▪ British
▪ Founding father of epidemiology
▪ Investigation of an outbreak (cholera, London 1854)
Ignasz Semmelweis
▪ Hungarian physician
▪ Puerperal fever in maternity hospitals in Europe
▪ High risk maternal death
▪ Doctors were the source of disease of their patients
o Washing hands before returning to their wards decline considerably the risk of puerperal fever
Florence nightingale
▪ British nurse
▪ Crimean war: Poor nutrition and hygiene, lack of medicines, and indifference lead to more deaths among
soldiers than battlefields injuries
▪ Plotted monthly deaths attributable to preventable and unpreventable causes
Janet Lane-Claypon
▪ British
▪ First (?) retrospective cohort study (1912): Weight gain during infancy and breast vs bottle feeding.
▪ First (modern) case-control study (1926): Breast cancer in relation to gestation parity and breast feeding ::::
Breast cancer epidemiology
▪ Study design, systematic and random error
Wade Hampton Frost
▪ First professor of epidemiology
1.3 Historical milestones in public health
Public health in the Middle Ages (500-1500)
▪ Quarantine as a tool to prevent spread
▪ Regimen sanitates: early guidelines for healthy living
Regimen Sanitatis Salernitanum
▪ Air, food and drink, sleeping and waking, motion and rest, excretions and retentions, and dreams and the
passions of the soul
▪ Use three physicions still; first Doctor Quiet, next Doctor Merry-man and Doctor Dyet (Harington's
translation, 1608)
▪ If doctors fail you, let these three be doctors for you: A joyful mind, rest, and a moderate diet (Modern
translation)
Mercantilism (1500-1750)
▪ Discovery that citrus fruit prevents scurvy
▪ Development of population statistics and civil registration: Quetelet Index (= BMI)
Age of Enlightenment and revolution (1750-1830)
4
! EXAM: don’t need to study the applied examples of guest lectures
H1 Introduction to epidemiology and public health
1.1 Epidemiology and public health
What is epidemiology?
Core idea
Epidemiology is consistently defined as:
“A method of reasoning about disease that deals with biological inference derived from observations of
disease phenomena in population groups.”
“The study of the occurrence of illness.”
WHO: “The study of the distribution and determinants of health-related states or events, and the
application of this study to control health problems.”
Purpose: epidemiologic research aims to fill knowledge gaps and ultimately improve public health
How epidemiology works
▪ Main method: counting within groups and comparing between groups
▪ Main challenges:
o Who to count? → defining the study population
o When to count? → timing, follow-up
o How to compare? → appropriate measures, valid contrasts
What questions does epidemiology answer?:
1. What is the burden of disease?
2. What is the prognosis of a disease?
3. Which risk factors/exposures cause disease?
Types of epidemiology
1. Descriptive epidemiology
a. Non-causal analyses which describe observed data (e.g. surveillance) Descriptive
b. Crucial foundation for analytic work!
2. Predictive (prognostic) epidemiology
a. Uses observed data to make statements or predictions about disease course
(e.g. used in clinical epidemiology)
Analytical
3. Causal (etiologic) epidemiology
a. Causal effects of risk factors/exposures on disease
i. Studies whether exposures cause disease
! Epidemiology is a multidisciplinary field that fits to the public health interest
Surveillance
Defined as the ongoing, systematic collection, analysis, interpretation, and dissemination of health-related data
Essential for:
Detecting changes in disease epidemiology
1
, Estimating incidence and burden
Monitoring prevention programs
Supporting public health authorities
Predicting spread
Example: Sciensano’s EPISTAT surveillance systems
What is public health?
Definitions
WHO: “The art and science of preventing disease, prolonging life and promoting health through the
organized efforts of society.”
Rothman: “The community effort to protect, maintain, and improve population health through organized
means.”
Role of public health
Public health activities include:
▪ Establishing health objectives and priorities
▪ Health promotion
▪ Disease prevention
▪ Health protection
▪ Health services
Approach of public health
A stepwise logic:
1. What is the problem? → Surveillance
2. What is the cause? → Risk factor identification
3. What works? → Intervention evaluation
4. How do we implement it? → Implementation science
Purpose of epidemiology in public health practice
Epidemiology helps to:
Discover the agent, host, and environmental factors that affect health
Determine the relative importance of causes of illness, disability and death
Identify those segments of the population that have the greatest risk from specific causes of ill health
Evaluate the effectiveness of health programs and services in improving population health
Applications of epidemiology in public health domains
1. Surveillance
a. Descriptive epidemiology used to set priorities and detect trends
2. Health services
a. Epidemiology evaluates:
i. Quality of care
ii. Need for more GPs
iii. Hospital practices (e.g., preventing antimicrobial resistance)
iv. Diagnostic test performance
3. Disease prevention
a. Primary prevention
i. Prevent disease before it occurs
ii. Examples: vaccination, mosquito nets, lifestyle changes
b. Secondary prevention
2
, i. Detect disease early, before symptoms
ii. Examples: mammography, blood pressure screening
c. Tertiary prevention
i. Manage disease after diagnosis to prevent complications
ii. Examples: rehab, chronic disease management, palliative care
4. Health promotion
a. Empowering people to improve their health
b. Examples: active transport, health literacy, healthy cities
5. Health protection
a. Minimizing exposure to hazards (e.g., water contamination, toxins)
b. Epidemiology provides evidence for identifying risks and evaluating interventions
1.2 History
Pioneers of epidemiology and public health
Hippocrates
▪ Greek physician and philosopher
▪ Diseases demonic possession and divine displeasure
▪ To physicians: Disease occurrence can be related to environment
▪ Earthly causes: “On Airs, Waters and Places”, at community of origin
▪ Behavior: “fond of drinking and eating to excess…”
▪ Change from mysticism towards observation and reason as causes of disease
Avicenna
▪ Persian philosopher, scientist and physician
▪ Empirical evidence and disease causation: experimentation and quantification
▪ One of the first ones to say that infectious diseases (ID) could be spread by contagion
o Quarantine to limit the spread of ID
Fracastoro
▪ Italian physician and poet
▪ Postulates some theories about how diseases spread
o Direct person-to-person contact
o Indirect contact
o Transmission at a distant (air or water)
▪ Also stated that health is affected by atmospheric conditions
John Graunt
▪ British
▪ World’s first epidemiologist and demographer
o Among the first to work on data
Bernadino Ramazzini
▪ Italien physician
▪ Occupational medicine
o Risks related to dozens of occupational hazards
o Review of suggestions for prevention and treatment
William Farr
3
, ▪ British
▪ Continued the work of Graunt
John Snow
▪ British
▪ Founding father of epidemiology
▪ Investigation of an outbreak (cholera, London 1854)
Ignasz Semmelweis
▪ Hungarian physician
▪ Puerperal fever in maternity hospitals in Europe
▪ High risk maternal death
▪ Doctors were the source of disease of their patients
o Washing hands before returning to their wards decline considerably the risk of puerperal fever
Florence nightingale
▪ British nurse
▪ Crimean war: Poor nutrition and hygiene, lack of medicines, and indifference lead to more deaths among
soldiers than battlefields injuries
▪ Plotted monthly deaths attributable to preventable and unpreventable causes
Janet Lane-Claypon
▪ British
▪ First (?) retrospective cohort study (1912): Weight gain during infancy and breast vs bottle feeding.
▪ First (modern) case-control study (1926): Breast cancer in relation to gestation parity and breast feeding ::::
Breast cancer epidemiology
▪ Study design, systematic and random error
Wade Hampton Frost
▪ First professor of epidemiology
1.3 Historical milestones in public health
Public health in the Middle Ages (500-1500)
▪ Quarantine as a tool to prevent spread
▪ Regimen sanitates: early guidelines for healthy living
Regimen Sanitatis Salernitanum
▪ Air, food and drink, sleeping and waking, motion and rest, excretions and retentions, and dreams and the
passions of the soul
▪ Use three physicions still; first Doctor Quiet, next Doctor Merry-man and Doctor Dyet (Harington's
translation, 1608)
▪ If doctors fail you, let these three be doctors for you: A joyful mind, rest, and a moderate diet (Modern
translation)
Mercantilism (1500-1750)
▪ Discovery that citrus fruit prevents scurvy
▪ Development of population statistics and civil registration: Quetelet Index (= BMI)
Age of Enlightenment and revolution (1750-1830)
4
