Evidence for Population Health Flashcards
What is anecdotal evidence?
evidence that comes from a patient themselves
describes their story and experience
What are the pros of anecdotal evidence?
quick
easy to perform in clinic
new conditions can be discovered
provides new potential risk factors
What are the cons of anecdotal evidence?
not scientific
affected by observer bias
difficult to conclude disease cause
What is cross sectional surveying?
observational study analysis of data collected from a population at one specific point in time
What are the pros of cross sectional surveying?
quick
good at estimating prevelance
What are the cons of cross sectional surveying?
only represents that point in time
cannot estimate incidence
may lead to bias
What is the incidence of a disease?
number of new cases in a given time
What is the prevalence of a disease?
number of cases of a disease that are present in a particular population at a given time
What is a common tool used to measure incidence?
a register
What is the counterfactual method?
predicting what would happen if…
would the disease have happened:
at the same time in the same person?
anyway if the factor was not present?
What are ecological studies?
observe a group
studies of risk-modifying factors based on populations defined either geographically or temporall
What are the pros of ecological studies?
cheaper
less prone to bias due to participation
easy to perform
provides new hypothesis about the cause of a disease/risk factors
What are the cons of ecological studies?
Ecological fallacy - conclusions about individuals based only on analyses of group data
Assume average value of the risk factor/incidence to all individuals
data collection may vary
What is a case-controlled study?
compares patients who have a disease (cases) with patients who do not have the disease (controls)
What are the pros of case control studies?
good for rare diseases/exposures
quick follow up
What are the cons of case control studies?
prone to selection/participation bias
finding a suitable control group can be difficult
difference in recall = bias
What is a cohort study?
passive follow-up of a group of people who share common experiences/conditions for the outcome
What are the pros of cohort studies?
good for rare exposures
can look at multiple outcomes
reduces information bias
direct measurement of incidence
What are the cons of cohort studies?
not useful for rare diseases
expensive
long
What is error in research?
the difference between an estimated value and true value
What is the definition of bias?
systematic, non random deviation of results and inferences from the truth
process leading to deviation
What is diagnostic bias?
when diagnosis is based only on exposure
What is self selection bias?
Can happen when:
participants contact the study - more likely to participate if FH
‘healthy worker effect’ - workers self selecting more likely to be healthier
What are the types of information bias?
Recall bias
Interviewer bias
Surrogate bias
and more…
What is misclassification bias?
occurs when data is placed into categories - can be put in the wrong categories
What is intention to treat?
A method of analysis for randomized trials in which all patients randomly assigned to one of the treatments are analysed together, regardless of whether or not they completed or received that treatment
What is randomised controlled trials?
AKA clinical trail
Random control and treatment group
Give treatment group intervention
Look at outcome
What are the pros of randomised controlled trials?
Strongest evidence for casuality
Selection bias/confoundering removed
Decreased observer bias
What are the cons of randomised controlled trials?
Not real life
High cost
Most of the time it is too inappropriate/unethical
