Module 5, Application of Evidence-based Principles

Question 1

What is evidence based medicine?

Answer 1

• we should apply the best evidence for medical research
• especially from RCT
• ““Integration of best research evidence with clinical expertise and patient values”

Question 2

What is the hierachy of evidence?

Answer 2

Question 3

What is the proposed new evidence based medicine pyramid?

Answer 3

• there can be other factors that can independent of the study design that can effect the qulaity of evidence that we derive from the study
• not only design of study that influences quality of study but also human factors
• the quality of a systematic review can only be as good as the individual studies quality that make up a review itself
• removed systematic review from the top and use it as a lens
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Question 4

What are the 5 steps of EBM?

Answer 4

1. Form an answerable question
2. Find the best evidence
3. Critically evaluate the evidence
4. Individualise response, based on professional expertise and patient concern
5. Evaluate your own performance

Question 5

How is this relevant to pharmacy practice?

Answer 5

• its a competency standard for pharmacists
• This standard encompasses the functions of accessing, analysing, interpreting and synthesising medical and pharmaceutical literature to clarify an evidence-based practice response appropriate for the clinical situation. This involves the use of professional judgement and strategic decision-making and the integration of complex information and may involve the creation of a written or verbal report for one or more professional colleagues

Question 6

Whats the concept of critical evaluation?

Answer 6

• What are the RESULTS?
• Are the results VALID?
• Are results RELIABLE?
• Are the results USEFUL?
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Question 7

Critical Evaluation- What are the results?

Answer 7

• Dichotomous variables; only 1 or 2 options for the outcome
  
  • Yes/ no
  • Alive/ dead
  • Pain/ no pain
• Continuous variables
  
  • Age
  • Hair length
  • or pain if we assess in terms of a pain score
• Terminology for controlled studies
  
  • Control group
  • Treatment or Intervention group

Question 8

Critical Evaluation- What are the results?

Answer 8

1. Descriptive:
   • Describe the population studied

• Age range
• Gender or ethnicity
• Cannot be generalized to any larger group

2. Inferential:

• Make predictions or inferences about a population from observations and analyses of a sample
• Sample must be representative of the larger population that it represents

Question 9

Critical evaluation- Are the results valid?

Answer 9

Were participants treated the same at the:

• Start
• During and
• End of the study?
• need to read about the study methodology; needs to be robust

Question 10

What do we need to consider when thinking about the quality of research?

Answer 10

• Randomisation
• Concealment and blinding
• Intention to treat analysis
• Baseline risk
• Confounding
• Looking at population subsets
• Type of outcomes
• Lost to follow-up leads to low quality of study
• Placebo effect
• Other factors…

Question 11

Critical evalutaion- Are the results reliable?

Answer 11

• CI Confidence intervals
  
  • expresses the precision of an estimate
  • measure of reliability
  • shows the range within which we’re confident that the true result from a population will lie 95% of the time
  • the narrower the interval; the more precise, the BETTER
• CI=1; no difference between the groups
• SD Standard deviation
  
  • Measures how much individual scores of a given group vary from the average (mean) score of the whole group
  • Measures the spread of the individual results around the average of all the results
  • High standard deviation: data widely spread i.e. less reliable
  • Low standard deviation: data clustered close to the mean i.e. more reliable

Question 12

Critical evaluation- Are the results useful?

Answer 12

• Consider clinical importance & size of benefit
  
  • Clinical importance
    
    • Consider the outcome measured
      
      • disease-orientated outcome (DOO) e.g. if new arthritis medicine reduces infkammaory markers
      • patient-orientated outcome (POO) e.g. if trial measured improvement in pain scores or patient mobility
  • should see mixed POO and DOO in most trials
• Size of benefit:
  
  • Absolute risk reduction (ARR)
  • Relative risk (RR) & hazard ratio (HR)
  • Relative risk reduction (RRR)
  • Number needed to treat (NNT)
  • Number needed to harm (NNH)

Question 13

Critical evaluation- Are the results useful?

Answer 13

• P-VALUE
  
  • is a measure of the strength of evidence against the null hypothesies
  • p<0.05 regarded as statistically significant
  • this means that there is a less than 1 in 20 chance of falsely observing a difference
  • the lower the P VALUE the more confident we can be about a result; we can say we are more confident that we’re achieving a true result
  • Statistical significance ≠ Clinical significance
  • Small differences between groups within a study may approach statistical significance, particularly if the population sizes are large
  • But, the difference may not be clinically meaningful

Question 14

What is Absolute risk (AR)?

Answer 14

• chance an outcome will happen
• simplest measure of association

Question 15

What is absolute risk reduction (ARR)?

Answer 15

• the risk difference
• difference in proportion of participants who had outcome in control compared with treatment group

Question 16

What is relative risk (RR)?

Answer 16

• compares the risk in 2 different groups of people
• tells us how many times more or less likely an event will occur in the treatment group compared with comparison group
• since the RR is less than 1.0, we can say that… XXX has made the risk of an MI less likely

Question 17

What is hazard ratio (HR)?

Answer 17

• if HR=1; relative probability of event in the 2 groups over time is the SAME
• if HR<1 or >1 it indicates that the relative probability of the event over time is greater in 1 of the 2 groups
• if CI linked with HR does not include 1; difference between groups is statistically significant

Question 18

What is relative risk reduction (RRR)?

Answer 18

• reduction and risk of an event in teh treatment group compared to risk in the placebo group
• estimates the proportion of baseline risk that is removed by the therapy
• i.e. treatment with XXX decreases the risk of MI by 25%

Question 19

What is the odds ratio (OR)?

Answer 19

• odds that an outcome will occur with a particular exposure, compared with the odds of the outcome occurring in the absence of that exposure
• OR=1 Exposure does not affect odds of outcome
• OR>1 Exposure associated with higher odds of outcome
• OR<1 Exposure associated with lower odds of outcome

Question 20

What is the number needed to treat (NNT)?

Answer 20

• Number of patients that we would need to treat with intervention to produce one positive outcome
• NNTs are usually rounded up

Question 21

What is the number needed to harm (NNH)?

Answer 21

• Number of patients that we would need to treat with intervention to produce one negative outcome
• NNHs are usually rounded down

Question 22

How can I apply the results to my patient’s care?

Answer 22

• Were the study patients similar to my patient?
  
  • inclusion/ exclusion criteria
    • limitations
• What if my patient does not fit the study inclusion/ exclusion criteria?
  
  • Look at the criteria your patient did not satisfy
  • Would that affect the outcome or applicability of the results to your patient?
  • Consider:
    
    • Studies in specific genders, ethnic or socio-economic groups
    • Age groups
    • Disease severity
    • Co-morbidities
• • treatments are not uniformly effective in every patient
    
    • trials estimate average treatment effects
• Were all clinically important outcomes considered?
• Are likely treatment benefits worth the potential harm and costs?