6. EBM - Kate Stewart Flashcards
Name the 5 steps of evidence based practice
- Asking focused questions
- Finding the evidence
- Critical appraisal
- Making a decision
- Evaluating performance
When we critically appraise evidence, what 3 things are we looking for?
Validity
Clinical relevance
Applicability
Name the 7 things on the traditional hierarchy of EBM
- Systematic reviews and meta analyses
- RCTs with definitive results
- RCTs with non-definitive results
- Cohort studies
- Case-control studies
- Cross sectional studies
- Case reports
What 4 domains can we use to grade the strength of evidence?
Risk of bias
Consistency
Directness
Precision
Define EBM
The integration of best research evidence with clinical expertise and patient values and expectations
Screening
- Define screening
- Name an advantage of screening
- Name 3 disadvantages of screening
- Identifying apparently healthy people who may be at an increased risk of a disease or condition. They can then be offered further information/tests that can lead to appropriate treatment to reduce the risk
- Early detection of disease = treatment successful
- Overdiagnosis, false alarms and missed cases
Screening &diagnosis
Define diagnosis
Establish presence/absence of disease as a basis for treatment decisions in symptomatic/screen positive individuals
Probabilistic reasoning (Bayesian reasoning)
- Define pre-test probability
- Define post-test probability
- Probability of having the disease before having the test
2. Probability of having the disease after having the test
- Define prevalence
2. What is the equation for prevalence?
- Proportion of people in a population who have a given disease or attribute (target condition)
- (TP➕ FN) ➗ (TP ➕ TN ➕ FP ➕ FN)
- What is a false positive result?
2. What is a false negative result?
- Individual referred for further assessment who does not have the target condition
- Individual not referred for further assessment who does have the target condition
- Define sensitivity
- Define specificity
- What is the equation for sensitivity?
- What is the equation for specificity?
- Proportion of people who have the disease and are correctly identified as such by the test AKA test catches right people
- Proportion of people who do not have the disease, and are correctly identified as such by the test AKA test has few false positives
- TP ➗ (TP➕ FN)
- TN ➗ (TN ➕ FP)
- Define positive predictive values
- Define negative predicative values
- What is the equation for PPV?
- What is the equation for NPV?
- Proportion of people with a positive test result who actually have the disease
- Proportion of people with a negative test result who do not actually have the disease
- TP ➗ (TP➕ FP)
- TN ➗ (TN ➕ FN)
- What kind of test result would we want a high likelihood ratio for?
- What kind of test result would we want a low likelihood ratio for?
- What is the equation for positive LR?
- What is the equation for negative LR?
- Positive result
- Negative result
- Positive LR = sensitivity ➗ (1 ➖ specificity)
- Negative LR = (1 ➖ sensitivity) ➗ specificity
What does 95% confidence interval mean?
0.95 probability of containing the population mean
What are 4 qualitative data collection methods?
- Observation
- Interviews
- Group methods
- Diaries and documents
Qualitative data recording: observation
- How is it recorded?
- Give 4 issues with this method
- Field diaries
- Ethics
Gaining access
Establishing rapport
Time consuming, labour intensive and costly
Qualitative data recording: qualitative interviews
- Topics to be covered or questions to be asked?
- Name 3 issues with this data collection method
- Topics to be covered
- Time constraints
Research agenda
Cost and access determine a level of structure
Qualitative data recording: group methods
- What is used?
- Name 3 issues with this kind of data collection method
- Focus groups
- Poor at capturing sensitive info/non-normative behaviour
Potential negative impact of group dynamic
Organisational issues (scheduling, location)
Qualitative data recording: diaries and documents
- What is used?
- Name 3 issues with this type of data collection method
- Existing material or solicited for research
- Time commitment
Legibility
Attrition
What are the 2 fundamental approaches to analysis and what do they mean?
- Deductive (top down)
Inductive (bottom up)
What are the 5 analysis stages?
- Identify initial themes
- Identify further themes for research development
- Coding transcripts to develop more detailed themes
- Discussion, refinement and application of coding categories
- Identify relationships between coding categories
- Development of key themes
- What can we use to evaluate qualitative research?
2. What are the 3 broad areas of this tool?
- CASP QAT
Critical Appraisal Skills Programme Qualitative Assessment Tool - Rigour (thorough and appropriate approach)
Credibility (findings well presented and meaningful?)
Relevance (findings useful?)
When coming up with a clinical research topic, what does PICO stand for?
Population
Intervention
Comparator
Outcome
What 4 things do we need to consider when selecting a study for a systematic review?
Time period
Setting (primary/ secondary)
Length of follow up
Published/ unpublished
What is the hierarchy of EBM starting with the top?
Guidelines
Systematic reviews of well controlled RCTs
Systematic reviews of cohort studies or lesser quality RCTs
Case controlled studies
Case series
Expert opinion
Name 4 weakness of RCTs
- Expensive and time consuming
- Often funded by drug companies
- Insufficient time for full follow up
- Generalisability
Name 4 weaknesses of cohort studies
- Expensive and time consuming
- Cohort effect
- Confounding
- Losses to follow-up
Name 4 strengths of case control studies
- Good for rare diseases
- High odds strongly suggest an association
- Quick and easy
- Many exposures can be studied
What are 4 disadvantages of guidelines?
- Speed
- Committees
- Health economics
- Implementation
- What is a surrogate outcome also known as?
- What can this mean for the size and length of trials?
- What is the alternative?
- What does ARR stand for?
- What does RRR stand for?
- Disease Orientated Evidence
- Smaller and shorter
- Patient Orientated Evidence that Matters
- Absolute risk reduction
- Relative risk reduction
- Define NNT
- Name 2 benefits of NNT
- Name 2 weaknesses of NNT
- Number needed to treat = average number of patients who need to be treated to prevent one additional bad outcome
- Comparing interventions for same condition
Estimating likelihood of patient benefiting from treatment - Doesn’t state which patients in particular benefit
Time dimension- maybe benefit just hasn’t been seen yet
- What does the p value test?
- Is this associated with statistical significance or clinical significance?
- What does CI tell us?
- Is this associated with statistical significance or clinical significance?
- Tests the null hypothesis (no difference between 2 treatments)
- Statistical significance only
- Confidence interval tells us the range within which the true value lies
- Both
What 3 things do we need to consider when thinking about whether clinical trial results are important?
Relevance
Magnitude
Precision
- What is the equation for ARR?
- What is the equation for RRR?
- What is the equation for NNT?
- In percentages
Control event rate ➖ experimental event rate - In percentages
(Control event rate ➖ experimental event rate) ➗ control event rate - NNT = 1 ➗ (ARR✖️100)
Name the stages of the 6S system
Systems Summaries Synopses of syntheses Syntheses Synopses of studies Studies
6S system: give an example of resources for the following stages of the 6S system
- Systems?
- Summaries?
- Synopses of syntheses?
- Syntheses?
- Synopses of studies?
- Studies?
- Computerised decision support systems
- Evidence based clinical practice guidelines / evidence textbooks
- Evidence based abstraction journals
- Systematic reviews
- Evidence based abstraction journals
- Original articles published in journals
