Intro to Epidemiology
W1 S1 Lecture notes
Epidemiology = patterns of determinants of health-related states or events
Tool used in public health, focusing on the prevention of disease and
promotion of population or communities
Help identify health problems in specific populations/communities
Identify causes of death
o Development of medication and prevention programs
study of population
Population = group of individuals who share common characteristics (age, sex,
country, or health)
Public health = science of preventing disease, prolonging life and promoting
health in populations
Epidemiological principles
- exposure, determinants, outcome, disease
- socioeconomic background, dietary habits
- principles often interrelated (ex. How lower socio-economic population
can be easily exposed to smoking behaviors)
Double burden of disease
- Having to tackle Infectious disease + non-communicable disease
Epidemiological transition = Changes in disease and health patterns in a
country due to development
Reading notes: Introduction to epidemiological thinking
Epidemiology = the study of the distribution and determinants of disease
frequency; the study of occurrence of illness
Confounding =
Seminar Notes
Grading
In-class participation (10%)
Individual assignment (15%): 750-word background
Group assignment: presentation on study design (15%) study proposal of
max 1500 words
Group assignment—final assignment (30%)
Final written exam (30%)
Determinants in epidemiology includes agents, causes, and risk factors “what
causes the disease?”
Distribution in epidemiology refers to who, when, and where
Epidemiology is about:
, What disease/condition is present in excess?
Who is ill?
Where do the live?
When did they become ill?
Why did they become ill analytical epidemiology
Designing epidemiological study
Develop your research question
Identify the magnitude and characteristics of the health problem
PICO system
P = patient/population
I = Intervention/exposure
C = control/prevention
O = disease/outcome/health state
W2 S1 Chapter 2
Lecture Video
Indicators of health and disease
Mortality rates (maternal, child, adult)
Life expectancy
Case-fatality rate
Incidence
Prevalence
Adult mortality = probability of dying between the ages of 15 and 60 years (per
1000) per year
Global public health surveillance
Life-expectancy estimates
To measure disease burden
Maternal mortality = death of a women while pregnant or within 42 days of
termination of pregnancy
Perinatal mortality = fetal death below 28 weeks of pregnancy or within 7
days of life
Neonatal mortality = death of a newborn between birth and first 28 days of
life
Life expectancy = the average number of years that an individual of a given
age is expected to live if current mortality rates continue
Case-fatality rate = the proportion of people who died from a disease within a
(short) time period
W2 S2 Webb & Bain, Chapter 5
, [Types of Epidemiological studies]
John Snow’s Cholera Cohort studies
Compared households water supplied by Southwark and Vauxhall company
versus Lambeth company
Estimates frequency of cholera death over household number. Households split
into two cohorts depending on water supply company
Discovered households that had water supplied by Southwark and Vauxhall
company were x14 fatal (attack rate x5.8 greater)than households water
supplied by Lambeth; reason to that is because Lambeth company changed the
water collection site from Hungerford Market upstream to Thames Ditton (less
contaminated water supply), whereas S.V company supplied sewage-
contaminated water from the Thames.
Proportion of cholera death/household: per 10000 houses
Southwark and Vauxhall = 71 death
Lambeth = 5 death
Role of investigator in natural experiment
Creativity and insight required
Ex) identified a precise setting to conduct the study: selected a neighbourhood where
both water supply companies’ pipes intermingled, which enabled Snow to identify
patterns.
Experiment = a study in which the incidence rate or the risk of disease in two or more
cohorts is compared after assigning the exposure to the people who constitute the
cohorts
Protocol = a set of rules by which the study is conducted
Types of epidemiological experiment: clinical trials, field trials, community intervention
trials
Randomization = produce comparability between the cohorts with respect to factors
that may affect the outcome under study
Field trial = aim to study the primary prevention of a disease rather than treatment of
an existing disease (ex. Vaccine trials – study participants are not patients)
Clinical trial
1. Cohort Studies
o A cohort is a defined group of individuals followed over time to observe
disease occurrence.
o Cohort studies compare disease rates
between exposed and unexposed groups.
o Closed cohorts (fixed membership) and open cohorts (dynamic
populations) are discussed.
o The classic example of a cohort study is John Snow’s natural experiment
on cholera transmission.
2. Case-Control Studies
o These studies compare individuals with a disease (cases) to those without
it (controls) to assess past exposure.
W1 S1 Lecture notes
Epidemiology = patterns of determinants of health-related states or events
Tool used in public health, focusing on the prevention of disease and
promotion of population or communities
Help identify health problems in specific populations/communities
Identify causes of death
o Development of medication and prevention programs
study of population
Population = group of individuals who share common characteristics (age, sex,
country, or health)
Public health = science of preventing disease, prolonging life and promoting
health in populations
Epidemiological principles
- exposure, determinants, outcome, disease
- socioeconomic background, dietary habits
- principles often interrelated (ex. How lower socio-economic population
can be easily exposed to smoking behaviors)
Double burden of disease
- Having to tackle Infectious disease + non-communicable disease
Epidemiological transition = Changes in disease and health patterns in a
country due to development
Reading notes: Introduction to epidemiological thinking
Epidemiology = the study of the distribution and determinants of disease
frequency; the study of occurrence of illness
Confounding =
Seminar Notes
Grading
In-class participation (10%)
Individual assignment (15%): 750-word background
Group assignment: presentation on study design (15%) study proposal of
max 1500 words
Group assignment—final assignment (30%)
Final written exam (30%)
Determinants in epidemiology includes agents, causes, and risk factors “what
causes the disease?”
Distribution in epidemiology refers to who, when, and where
Epidemiology is about:
, What disease/condition is present in excess?
Who is ill?
Where do the live?
When did they become ill?
Why did they become ill analytical epidemiology
Designing epidemiological study
Develop your research question
Identify the magnitude and characteristics of the health problem
PICO system
P = patient/population
I = Intervention/exposure
C = control/prevention
O = disease/outcome/health state
W2 S1 Chapter 2
Lecture Video
Indicators of health and disease
Mortality rates (maternal, child, adult)
Life expectancy
Case-fatality rate
Incidence
Prevalence
Adult mortality = probability of dying between the ages of 15 and 60 years (per
1000) per year
Global public health surveillance
Life-expectancy estimates
To measure disease burden
Maternal mortality = death of a women while pregnant or within 42 days of
termination of pregnancy
Perinatal mortality = fetal death below 28 weeks of pregnancy or within 7
days of life
Neonatal mortality = death of a newborn between birth and first 28 days of
life
Life expectancy = the average number of years that an individual of a given
age is expected to live if current mortality rates continue
Case-fatality rate = the proportion of people who died from a disease within a
(short) time period
W2 S2 Webb & Bain, Chapter 5
, [Types of Epidemiological studies]
John Snow’s Cholera Cohort studies
Compared households water supplied by Southwark and Vauxhall company
versus Lambeth company
Estimates frequency of cholera death over household number. Households split
into two cohorts depending on water supply company
Discovered households that had water supplied by Southwark and Vauxhall
company were x14 fatal (attack rate x5.8 greater)than households water
supplied by Lambeth; reason to that is because Lambeth company changed the
water collection site from Hungerford Market upstream to Thames Ditton (less
contaminated water supply), whereas S.V company supplied sewage-
contaminated water from the Thames.
Proportion of cholera death/household: per 10000 houses
Southwark and Vauxhall = 71 death
Lambeth = 5 death
Role of investigator in natural experiment
Creativity and insight required
Ex) identified a precise setting to conduct the study: selected a neighbourhood where
both water supply companies’ pipes intermingled, which enabled Snow to identify
patterns.
Experiment = a study in which the incidence rate or the risk of disease in two or more
cohorts is compared after assigning the exposure to the people who constitute the
cohorts
Protocol = a set of rules by which the study is conducted
Types of epidemiological experiment: clinical trials, field trials, community intervention
trials
Randomization = produce comparability between the cohorts with respect to factors
that may affect the outcome under study
Field trial = aim to study the primary prevention of a disease rather than treatment of
an existing disease (ex. Vaccine trials – study participants are not patients)
Clinical trial
1. Cohort Studies
o A cohort is a defined group of individuals followed over time to observe
disease occurrence.
o Cohort studies compare disease rates
between exposed and unexposed groups.
o Closed cohorts (fixed membership) and open cohorts (dynamic
populations) are discussed.
o The classic example of a cohort study is John Snow’s natural experiment
on cholera transmission.
2. Case-Control Studies
o These studies compare individuals with a disease (cases) to those without
it (controls) to assess past exposure.
