Evidence Based Medicine Flashcards
what is the best type of evidence?
systematic review
what are the three main types of study design?
observational descriptive
observational analytical
experimental
name two types of observational descriptive studies
case reports
case series
name three types of observational analytical studies
cross sectional study
case control study
cohort study
name a type of experimental study
randomised control trials
what two things are looked at when selecting patients for RCTs?
inclusion criteria
exclusion criteria
state some examples of inclusion criteria for RCTs
likely to benefit from the treatment
unlikely to be harmed
name some examples of exclusion criteria for RCTs
clear preference for the intervention or control by the patient or the doctor
patient unlikely to adhere to the treatment or follow up
what is the aim of patient selection in RCTs?
have a well defined group with an increased likelihood of detecting an effect
what is the rule of thumb when it comes to losing patients in RCTs?
fewer than 20% lost with similar losses for the intervention and the control
what is confounding?
when the association between an exposure and an outcome is actually the result of another variable
what is absolute risk (AR)?
the number of events in treated or control groups, divided by the number of people in that group
what is the ARC?
the AR of events in the control group
what is the ART?
the AR of events in the treatment group
how do you calculate the absolute risk reduction (ARR)?
ARC - ART
how do you calculate the relative risk (RR)?
ART/ARC
how do you calculate the relative risk reduction (RRR)?
(ARC-ART)/ARC
how do you calculate the number needed to treat (NNT)?
1/ARR
what are some qualitative research methods?
ask people
observe people
what is triangulation>
when the area under investigation is looked at from different perspectives, with two or more research methods
what is the role of triangulation?
ensure understanding is as complete as possible
confirm interpretations
what is sensitivity?
how well a test detects having the disease
how do you calculate sensitivity?
number of true positives/number of people with the disease x100
describe what a highly sensitive test will do
pick up most of the disease whilst having very few false negatives
what is specificity?
how well a test picks up not having the disease
how do you calculate specificity?
number of true negatives/number of people without the disease x100
describe what a highly specific test will do
correctly detects no disease with very few false positives
what is the positive predictive value?
how reliable a test result is when it shows disease is present
how do you calculate positive predictive value?
true positives/all positives x 100
what is the negative predictive value?
how reliable a test is when it shows that disease is not present
how do you calculate negative predictive value?
true negatives/all negatives x100
what can affect the predictive values?
prevalence of disease
what is opportunity cost?
a benefit that a person could have received but gave up to take another course of action
name three types of economic evaluation
cost effective analysis
cost utility analysis
cost benefit analysis
what is the best study design to determine the prevalence of a disease?
cross sectional study
in a randomised control trial, what is reduced by randomisation?
selection bias
what study type is being described: a study that looks at all children born at a hospital in one year, measuring their height at intervals up to four years of age?
cohort study
what does external validity mean?
the extent to which one can appropriately apply results from a study to other populations
what is the best study design to research the aetiology of a disease?
cohort study
what does statistical significance mean?
the results of a study are unlikely to have arisen by chance alone
what measure seeks to measure the benefits to individuals following a medical intervention?
QALYs
what is saturation?
when there is no longer any need to sample more people to reach new conclusions or to back up/challenge existing conclusions
