Lecture 2: Population-level study design Flashcards
What is Humourism?
Ill health caused by imbalances in four fundamental characteristics
Humorism was based on the idea that four essential fluids (blood, yellow bile, black bile, and phlegm) in the body controlled a person’s health and personality
What are the 4 characteristics of Humourism?
- Incorporated roles of temperament.
- Seasons
3.Climate - Alchemic elements
What treatments were used during Humourism?
Blood letting
Laxatives
Emetics
What did Vrchov introduced to western medicine?
Cellular Pathology
(1840s)
What did Snow introduce to western medicine?
Epidemiology
(1850s)
What did Pasteur introduce to western medicine?
Microbiology
(1860s)
What does the practice of Evidence based medicine intergrate?
1) individual clinical expertise
2) the best available external clinical evidence
3) Patient values & expectations
How do you formulate an Evidenced based Medicine research Questions?
(5 As cycle)
- Ask: Formulate a research question
- Access: Find and retrieve the ‘best evidence’
- Appraise: Consider the evidence for its validity & relevance
- Apply: Integrate the of results into clinical practice
- Assess: Evaluate the effectiveness
Which type of studies contains filtered infromation?
Critically-Appraised Individual articles
Critically Appraised Topics (Evidence Syntheses)
Systematic Review
Which type of studies contains filtered information?
Critically-Appraised Individual articles
Critically Appraised Topics (Evidence Syntheses)
Systematic Review
Which type of studies contains unfiltered information?
Randomised Controlled Trials
Case-Controlled Studies
Cohort Studies
What type of studies does the TRIP data base Seach for simultaneously?
Background Information/Expert Opinion
What are the 4 types of evidence?
- Description
- Prediction
- Casual Inference
- Qualitative
What is description evidence?
What happened?
Who was affected?
People with X had Y
What is Prediction evidence?
What will happen?
Who will be affected?
People with X are more likely to have Y?
What is Casual Inference evidence?
What will happen if…?
Why were they affected?
If we changed X, how would it change Y?
What is Qualitative evidence?
What matters…?
Why does it matter?
How can we effectively change X…?
Should we change X?
Is studying individual people useful with probabilistic events?
NO.
People are very different
Even the same people can respond very differently at different times
What group are we most interested in in most instances?
Population
What do we use samples of the populations?
The population is often impossible or impractical to study
What is clinical research?
Focused on understanding and helping individuals
What is population health Research?
Focused on understanding and helping populations
What is a census?
Total population.
What is a population-based study?
a total population of a country or area
What is a case report?
Study of a singular person.
What happens during a Case report?
Describing what happened
Describing her symptoms etc
What is a Case series?
a report written on a sample of cases with the same disease allowing for predications of prognosis, survival rate, symptoms and other health-related outcomes to be predicted
What do Case series look at?
Allows for description of natural history & prediction of prognosis:
Frequency and range of symptoms
Typical duration
Typical survival
Range of prognoses
Predictors of prognosis
What are Register- based Studies?
Special type of case-series
a type of case series that uses regional disease registers to count and collect information on people based on a particular disease
These are commonly population-based, so you can estimate the disease occurrence per population
What are disease registers?
count and collect information on people diagnosed with a particular disease
What is a Cross-sectional study?
a study of a group of people at a single point in time
What does a cross- sectional study involve?
Directly surveying or measuring a group of people
Gathering routinely-collected data
What is meant by ‘stratified’?
Descriptive studies usually also report their results broken down (‘stratified’) into subgroups
What are Common characteristics for stratification?
Age
Sex
Socio-economic position
Self-reported ethnic group
Marital status
Occupation
What are Cohort Studies?
Cohort studies examine groups of people over time
What is Hypothesis generation?
Descriptive studies often present multiple stratified results, to generate hypotheses
What are common variables Hypothesis generation?
Individual-level characteristics
Age, sex, socio-economic position, ethnic group, marital status, occupation
Area-level characteristics
Countries, regions, latitude, urban vs rural areas, more vs less deprived areas,
Temporal characteristics
Secular trends (i.e. over time)
Dynamic or seasonal trends (e.g. month, season, day of week)
What are case control studies?
Case-control studies examine groups of people over time retrospectively
What are advantages of Case-control studies?
Good to study rare diseases
Can investigate multiple exposures at a time
Cheaper and less time consuming than a long-term cohort study
What are disadvantages of Case control studies?
Recall bias
Need for suitable control group
Can establish correlation but NOT causation
What is an ecological study?
A study that examines variations between geographical areas is called an ecological study
What are ‘units of analysis’ in ecological studies?
Not individual people, but an area.
What is the relationship between ecological studies and hypotheses?
Ecological studies are weak for testing hypotheses, but can be useful for generating hypothesis
