the science of EBM Flashcards
what are the different types of observational study?
- case control
- cohort
- cross sectional
what are examples of experimental studies?
- randomised and non randomised trials
what are the principle of evidence based medicine?
1) patient dilema
2) ask
3) acquire
4) appraise
5) apply
6) act and asses.
what are examples of reviews?
- expert opinion
- systemic review
- meta-analysis
what are the 8 levels of evidence?
what are 5 factors that might decrease the quality of evidence?
- study limitations
- inconsistency of results
- indirectness of evidence
- imprecision
- publication bias
what are 3 factors that might increase the quality of evidence?
- large magnitude of effect
- plausible confounding, which would reduce a demonstrated effect
- dose response gradient
what are the advantages of case studies?
- quick and cheap to conduct
- rapid publication
- early indications of problems
- can help detect new drug side effects and potential uses
what are the 4 disadvantages of case studies?
- statistically weak
- no control group
- vert small numbers of patients
- cases may not be generalised to the wider population
wha are the advantages of cross sectional survey?
- cheap and simple
- ethically safe
- useful for planning purposes
what are the disadvantages of cross sectional study?
- cause and effect?
- volunteer bias
- unequal distribution of confounders
what are 2 complications that may arise in studies?
confounders = uncontrolled extraneous variables
- observation, smokers tend to have smaller babies than non smokers
SPURIOUS ASSOCIATION
- it understand harmful to the foetus?
= - initial studies showed that babies exposed to ultrasound has a lower birth weight
- later studies failed to confirm this observation.
how do case control studies work?
advantages of case control studies?
- youcan look at multiple rosk factors at once.
- good for studying rare conditions or diseases with long latent period
- useful as initial studies to establish an association
- do not require a long follow up period
disadvantages of case control study?
- retrospective study which relies on patient recall to determine exposure or patient records
- confounders
- selection of control group is difficult
- unlikely to detect rare causes of disease
how does a cohort study work?