Intro to Epidemiology Flashcards by An Nakamura

Definition of epidemiology

Study of the distribution and determinants of health events and health related risk factors in specified populations
This knowledge is used to plan and evaluate strategies to prevent/manage disease in specified populations

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Definition of epidemiologist

Public health scientist who analyses patterns, causes, effects of health and disease in populations

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Definition of ecological epidemiology

Ecology of disease
Interaction between hosts and pathogens
Includes population and community level studies

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Definition of molecular epidemiology

Contribution of genetic and environmental risk factors at the molecular level

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Definition of descriptive epidemiology

Examination of frequency/geography of disease over time

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Definition of etiological epidemiology

Study the causes of a disease

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Definition of evaluative epidemiology

Study effects of preventative measures on outcomes

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Definition of health service epidemiology

Study effects of outcomes and effectiveness of health services

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Definition of clinical epidemiology

Study of the natural course of a disease and the effects of diagnostics and procedures

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Definition of target populations

Total group of individuals from which the sample is drawn

Conclusions from study made on this population

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Definition of the study population

Group of individuals in a study

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Definition of sample population

Subjects that provide data

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Definition of prevalence

No of existing and new cases of a disease in a time frame

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Definition of incidence

No of new cases of a disease in a time frame

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What is epidemiology

Study of the distribution and determinants of health events and risk factors in specified populations
Knowledge applied to plan/evaluate strategies to prevent/manage disease in specific populations

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What did Hippocrates do in 400BC

Made the link between disease and environmental influences

Father of epidemiology

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What did Nightingale, Koch and Snow pioneer in 1800

Infectious disease epidemiology

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What was the new type of epidemiology being investigated in 1900 before WWII

Non infectious disease epidemiology

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What considerations were being made in epidemiology in 1900 after WWII

Consider deliberate spread as well as natural spread
Chronic diseases
Emergence of new diseases
Eco epidemiology
Molecular epidemiology

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Describe the use of John Snow’s spot map

Locations of water pumps and incidences of cholera plotted on a map
Most cases around Pump A => most likely cause of epidemic
Handle removed => prevented further spread

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What are the 5 main applications of epidemiology

Community diagnosis
Measure risk
Assessment, evaluation, research
Identify syndrome
Find causes

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What are the 5 main areas in epidemiology

What do they do

Descriptive
-examination of frequency/geographical areas over time

Aetiological
-study causes of disease

Evaluative
-effect of preventative measures on outcomes

Health services
-effect of outcomes and effectiveness of health services

Clinical
-natural course of disease and effects of diagnostic and procedures

What are the 3 main factors that relate to the causation of a disease

Based on the assumption that events => other events

Multicausality

genetic
environmental

Strength of cause
-when 1 cause has a greater effect than another

Induction time
-period of time between receipt of exposure and first presence of disorder

What is Rothman’s causal pie

Each contributory factor = pie slice

When the pie is complete => disease occurs

What are the 3 types of population considered in an epidemiological study

Target population - total group of individuals from which the sample is drawn - conclusions on population made from studies Study population -group of individuals in a study Sample population -subjects that provide data

What are the 3 measures considered in an epidemiological study

Measures of frequency - prevalence - incidence Measures of association Measures of impact

What 3 considerations do you have to make when measuring the prevalence of a disease How do you measure prevalence

Existing cases Population at risk Time period where prevalence applies (New and pre existing cases of diseases in given timeframe/Total population during same timeframe ) x 10^n

What 3 considerations do you have to make when measuring the incidence of a disease How do you measure incidence

New cases Population at risk Timeframe (Total no of new cases of a disease in a time frame/Total population at risk in same timeframe 0 x 100^n

What 3 considerations do you have to make when measuring the associations in a disease What is association

Relative risk Risk ratio Odds ratio Assess strength between variables

What 2 considerations do you have to make when measuring the impact of a disease What is impact

Attributable risk Vaccine efficacy and effectiveness Impact of disease in population Impact of eliminating risk factors

What are the 8 disease frequency components

1. Categorise disease 2. What is considered a true case of disease 3. How to ascertain cases 4. Define population at risk 5. Define timeframe at risk 6. Consent to study people 7. Measure disease frequency 8. Relate frequency to population and time at risk

How do you measure the cumulative incidence of disease in a group

(No of people with disease + factor)/(No of people with factor) x 100

How do you measure the risk ratio / cumulative incidence ratio

(Cumulative incidence of disease in people with factor)/(Cumulative incidence of disease in people without factor)

How do you measure the risk difference

(Cumulative incidence of disease in people with factor) - (Cumulative incidence of disease in people without factor)

How do you measure the odds ratio

(Disease and factor) x (No disease and no factor)/(No disease and factor) x (Disease and no factor) AD/BC

How do you measure the potential impact | What is the significance of this value

Attributable risk/Incidence exposed x 100 = AR% Attributable risk = Incidence exposed - Incidence unexposed Gives you a percentage of how many cases are attributable to 1 cause If not 100%, other factors are responsible

What are the 2 types of epidemiological investigtaion

Descriptive | Analytical

Describe the 3 characteristics of a descriptive investigation Name the 6 applications

Patterns of disease occurrence By person, time, place Data easily accessed ``` Vital stats Periodic surveys Comparisons Program planning Hypotheses generation Future research ```

Describe the 3 characteristics of an analytical investigation Name the 4 applications

Disease etiology focused Resource intensive Use comparison groups Determinants of disease Find risk factors Hypotheses testing Modes of transmission

What is the epidemiological triad | What is the significance of it

Place Person Time Helps us understand distribution of disease

What are the 2 types of epidemiological study designs

Experimental -shows that A=>B Observational -No manipulation of factors

What are the 4 properties of experimental epidemiological study designs What are the 2 concerns of this design

Manipulation Control Randomization Blinding Unethical to cause disease Not always feasible

What are the 4 properties of observational epidemiological study designs What are the 3 concerns of this design

Non experimental Non controlled Natural grouping Concept of time Confounders Selection bias Measurement errors

How does the cost of a study relate to the validity

The greater the cost => the greater the validity | -Interventional trials are generally the best

What are the 3 main sources of error in studies

Selection bias Information bias Confounders

What are the 4 forms of selection bias in study errors

Self selection Non response to interviews Attrition, not everyone continues to take part Selection survival, healthier people generally stay

What are the 3 forms of information bias in study errors

Reporting bias, memory issues False -ve/+ve, diagnostic errors Error and omissions in medical records

What are the main confounders in studies

Differences in age, gender, health status

What can confounders cause

False associations False lack of an association Under/overestimate of an effect

How do you reduce the effect of confounders

Randomising individuals Filter out groups Stratify analysis

What are the 2 main types of data source

Aggregate data -generally easier to obtain Individual level data - can be obtained but not as easily - generally needs consent

What are 4 examples of aggregate data

Vital stats Census Disease registries Monitoring systems

What are 5 examples of individual level data

``` Vital events Disease registries Medical records National surveys Questionnaire data ```

What are the 4 main ethical issues regarding epidemiological research

Confidentiality -need consent to gather info except in public emergency Autonomy Justice -people being tested must benefit themselves Beneficence - minimise harm - maximise benefit