evidence based medicine & practice Flashcards
what is evidence based medicine
the conscientious, explicit and judicious use of the best evidence in making decisions about the care of individual patients
what does the practice of evidence based medicine mean
integrating individual clinical expertise with the best available external clinical evidence from systematic research
when was the EBM movement
1990s
what was the EBM movement against
- paternalistic decision making (doctor knows best)
- hierarchies of medical authority (specialist knows best and does best)
- knowledge limited to the few
- subjective self assessment of practice
what did the EBM movement move towards
- shared decision making (doctor and patient know complementary things )
- science (clinical evidence) above authority
- development and dissemination of skills to use clinical evidence
- evaluating whether practice is in keeping with evidence
what are the five key elements of EBM
1) finding evidence (asking the right questions )
2) assessing the evidence (critical appraisal)
3) synthesising the evidence (bringing it all together )
4) making good decisions
5) evaluating performance against the evidence
define evidence
information to inform clinical practice that is obtained by scientific methods
what are the 4 major study designs as sources of evidence
1) cross sectional survey
2) case control
3) cohort
4) randomised controlled trial (RCT)
what is an observational study
studying what is happening to people
what is an experimental/intervention study
studying the effect of an intervention or treatment
define sample
the people on whom the study is conducted
define exposure
whether/ how much the individual is exposed to the things that are hypothesised to influence the outcome
define outcome
the thing you are interested in happening (or not happening)
how do you carry out cros sectional study design
start with population
see how many have the dato variables
how do you carry out case control study design
take sample of people with one problem and a sample of people with the other
compre the prevalence and match who have both
how do you carry out cohort study design
take a sample of unaffected people and measure exposure to the risk factor
after a period of time record how many people in the exposed / unexposed group develop the outcome
but differences may still be due to other factors
how do you carry out randomised controlled trial (RCT)
take a sample of patients with condition or risk of interest
randomly allocate one group to intervention or control
follow them for a period of time and measure outcome
randomisation reduces risk that any difference is due to unknown or unmeasured factors
what is the hierarchy of evidence ( best method to worst)
1) RCT
2) cohort
3) case control
4) cross section
5) case series
how do you structure a question to look for evidence
PICO
patient or population (under study)
intervention(exposure, treatment or procedure)
comparator/control (that which is compared against the intervention)
outcome ( endpoint of interest)
what are some sources of evidence
- high quality guidelines (eg NICE, international speciality organisations)
- systematic reviews eg Cochran reviews and structured evidence summaries
-databases eg MEDLINE, EMBASE, CINAHL, Pubmed) - grey literature - published but not peer reviewed eg project repostas
- medical journals, reference books
how to assess evidence (critical appraisal)
- did it use an appropriate design
- is it at low risk of bias
- was it well conducted
- has it been well reported
- is it making claims justified by its scope and findings
what are the tools for critical appraisal
- critical appraisal skills programme ( CASP)
- NICE guidelines manual checklists
- Cochrane handbook for systematic reviews for intervention - cochranes collaborations tool for assessing risk of bias
how do you synthesise evidence
narrrative synthesis - describing the results and telling their story
meta analysis - statistical technique for combining the results of multiple studies
qualitative synthesis
how do you make good decisions
1) is the evidence good enough that I should use it in my clinical decision
2) does it apply to the patient in front of me
3) how should we make the clinical decision
- doctor led
-patient led
- shared decision
how do you evaluate performance
- EBM isn’t a single once off step but a process of ongoing reappraisal
- is the evidence I used before still robust
- am I actually doing what the evidence tells me is the best thing
- am I confident in the evidence, am I simply imposing it on people or am I using it to make shared decisions with patients
