Evidence Based Veterinary Medicine Flashcards
What is EBVM
The process of systematically reviewing, appraising and using clinical research findings to aid the delivery of optimum clinical care to patients
- Basically the logical way of reviewing evidence critically to ensure you’re making the correct decision for your patient
What is the approach to EBVM?
- Ask specific Q
- Search for best info
- Critically appraise info
- Apply to clinical situ (relevant to patient?)
- Review and update as required
How to ask a specific question?
Asking specific question:
Diagnosis, therapy
Prognosis, prevention
PICO Patient - define P adn condition Intervention - define drug or procedure Comparator - Active control or placebo Outcome - define clinical response
Search for best info: what comes under this?
- Anecdote and / or expert opinion (weakest form of evidence!!)
- textbooks
- Continuing professional development - conferences, webinars
- journals
- databases
- internet and news media
Critically appraise the info
Assessing and interpreting the evidence
by systematically considering its validity,
results and relevance to the area of work
considered
1. Assess all evidence - depth, quality adn balance of evidence
2. Use the hierarchy of scientific evidence
State the hierarchy of scientific evidence, strongest to weakest
- Strongest = meta analysis and systemic reviews
- Randomised controlled trials
- Cohort studies
- Case control studies
- Cross sectional studies
- Animal trials and in vitro studies
- Case reports and series, opinion papers, letters
Talk about bottom of hierarchy: Case reports and case series
- Descriptions of clinical cases
- Detailed clinical history
- CR - typically single case, sometimes 2
- CS - many cases with similar pattern
- typically write about if something interesting, unusual or novel e.g. new drug
- Peer reviewed, so better than anecdote
- Typically RETROSPECTIVE - gather info then write, issues with reliability
- CS typically uncontrolled e.g. don’t compare with other treatments so can’t be sure if response reflects reality
- Often written at uni or referral - relevant to primary care?
Case controlled study
- half way up hierarchy of info
o Compare cases with a group of controls
o Usually retrospective (like case series but try to compare outcomes in particular bunch of cases with some controls)
E.g. cats with abscess treated with one drug, find new bunch which are virtually identical to historical records but diff treatment. AIM- match cases to controls
o Not blinded or randomised
Why is case control better than case series
Due to some degree of control (Comparing cases with group of controls)
but retrospective so limited with info. Also don’t necessarily know reasons treatments were used at the time. E.g. could be due to cost rather than same reason. Can be bias meaning validity isn’t great. Better than CS though!
Cohort study
o Follow cases to see what happens to them
o Can assess different treatments
o Not blinded or randomised
o Typically prospective and longitudional
o Come up with hypothesis and then next 100 cases, enrol in same way, give treatment and see what happens:
- Not clouded by previous judgements
- Can judge outcome as unfold
- Takes longer to get info but better as gather correct info to answer Q
o Not perfect as not randomly assigning them so can’t be sure if difference is deffo due to treatment you are interested in
Randomised control trial
o What we really want to find when investigating EBVM
o Only difference between whether case gets treatment or control is random chance
o More reliably than any previsios versions which are subject to bias.
o Control: other treatment or placebo
o Always prospective
o Often blinded- individuals don’t know what treatment got
How do cohort adn randomised control studies vary?
o Similar to Cohort study as longitudional and prospective. Dofference is randomly allocate cases either to treatment interested or some form of control
Systematic review
- highest quality, along with meta analysis
- Review of all published research in a field
- Critical appraisal
- Quality of evidence
- Report and summarise findings
MAta analysis
o Also a systematic review
o Uses stats to integrate results of different studies
o Combine results of other studies and do further statistics
Where can bias come in in clinical trials?
a. Selection
i. Systematic differences between the baseline group characteristics
ii. Not random patient allocation increases the chance of a study having a positive outcome by 30%
b. Performance
i. Groups handles differently during trial
c. Detection
i. Systematic differences in how the outcomes are scored between groups
d. Attrition
i. Systematic differences between groups in withdrawals from a study
e. Publication
