Epidemiology 2

Question	Answer
What is the triangle of causation?	Agent-Host-Enviroment (Back to agent)
What is the web of causation?	Disease in the centre with causalities pointing off; eg: Age, genetics and lifestyle
What are the levels of social determinants?	Individual-Age, genetics, gender Lifestyle-Exercise, nutrition, alcholol, sleep Activities-Gym, work, shopping, playing Local community; Peers, volunteering, social interactions Local economy and enviroment-Greens, employment, housing
Link epidemiological research to exposure	Epidemiological research often studies population with exposure and without exposure
Types of epidemiological study?	Observational-Descriptive or analytical Interventional-Effect on populations after interventional/ enviromental influences
What types of observational research design are there?	Descriptive-Case reports and series, cross sectional studies and ecological studies Analytical-Case controls and cohort studies
What types of interventional research are there?	Randomised controlled trials and other*
What is the typical pathway of a causal observation?	Clinical observation Descriptive study Analytical study Experimental reproduction Interventional study
What are observational descriptive studies used for?	Describe patterns of health and disease Generate hypotheses Inform planning Evaluate interventionn
What are case series/reports?	Document of an unusual case Used to generate hypothesees Often used to produce a first clue to the cause They're the most basic desciptive study
What are the limitations of case series/reports?	Few participants-High chance therefore less valid data No control group therefore no differences can be infered Very selective cases-Very hard to generalise to pop
What are ecological studies?	Describe patterns of health and disease in relation to exposure and risk factors in entire populations Data is aggregated to a population level-cannnot describe exposure and risk factors of individual Uses routine data sources Can compare trends over time
What the strenghs of ecological studies?	Repeated over time can measure change Simple and cheap Study group effects of exposure and disease
What are limitations of ecological studies?	Ecological fallacy-cannot explain exposure and risk of disease at individual level Lacks infomation on confounding factors Misses possible effects in small sub groups and also at the individual level
What are cross sectional studies?	Take a snapshot of exposures AND outcomes in a population at a single point in time Can be purely desciptive-The frequency of disease Can be analytical also-links risk factor to an outcome
What are strenghts of cross sectional analysis?	Cheap and quick Can compare data through time Establishes prevalence for risk factors and outcomes
What are the limitations of cross sectional studies?	Sample must be representative-if not cannot be generalised Data of exposure and outcome are collected at the same time-No causation and risk info may be retrospective
What is the purpose of analytical studies?	Build on descriptive studies to start to investigate causation
What is a case control?	Compares individuals with and without disease Begins with those who have a disease and looks back at their past
What are the strengths of a case control?	Relatively cheap Cann assess multiple aetiologies of one disease Useful for rare diseases
What are the limitations of case controls?	May have selection bias May have recal bias Temporal relationships are not always clear
What is a cohort study?	Follow a group in a longtitudinal study to estimate risk of disease Cohort share common charceristics or experiennce in a defined period of time
What are the strenghts of a cohort study?	Clear temporal relationships Direct measure of incidence is possible Can be used for rare exposures
What are the limitations of cohort studies?	Expensive and time consuming Less useful for rare diseases Lost to follow up often effects validity
What are experimental/interventional studies?	Intervention is applied to a population to observe if outccomes can be prevented Randomisation and blinding are used to prevent/reduce bias Researcher allocates the exposure status to a study population
What are the strenghts of experimental/interventional studies?	Can be very high quality Randomisation removes known and unknown cofounders Blinding minimises the risk of bias
What are the limitations of experimental/intervential studies?	Expensive and time consuming If population is not representative the data cannot be generalised Likely to still have biases present-Lost to follow up being a key one
What is chance?	The outcome occured due to chance alone-not exposure As population increases the probability of chance decreases Null hypothesis=the results were down to chance
What is bias?	Prejudice of data leading to less valid data
What types of bias is there?	Information bias-Systematic differences in the way data on exposure or outcome are obtained Selection bias
What makes a cofounding variable?	Must be associated with disease Must be associated with exposure Association between the cofounder and disease must be independent to exposure Cofounding factor cannot be intermediate within the pathway of the exposure and disease

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	Created by Joe carlow over 8 years ago