Intervention Flashcards
What are the barriers to EBP?
- lack of time
- lack of training
- lack of quality research evidence
How does CrowdCARE address the barriers to EBP?
- lack of time –> shares critical appraisals
- lack of training –> provides tutorials on EBP and critical appraisal
- lack of research evidence –>
spreads critical appraisal load
What is the purpose of critical appraisal?
- Determines quality of evidence of a study
- enables us to give different weight to different studies when making clinical decision
3 basic questions to be answered in critical appraisal?
1) Are the results valid? (Internal Validity)
2) Are the results of value? (Clinical Significance)
3) Do the results help in caring for my Px? (External Validity)
Construct a Clinical Question for-
What are the search terms?
You are an optometrist working in Melbourne. In your practice, you have some teenagers with myopia who display rapid progression. You usually just recommend good visual hygiene. During a consultation today, one parent mentioned a news report about a ‘breakthrough’ from overnight orthokeratology lenses on myopia progression, and asked if you can prescribe them. You search the literature to see if there is any evidence of their effectiveness.
Patient: teenager with myopia
Intervention: orthoK lenses
Control: No orthoK lenses
Outcome: slowing myopia progression
Question: Do OrthoK lenses reduce myopia progression compared to no orthoK lenses in teenagers with myopia
Search terms: myop* AND orthokeratology AND progres*
What is the gold standard study for Intervention Questions?
Randomised Control Trials
What is a Randomised Control Trial (RCT)?
- randomly divide participants into 2 groups
- one group gets intervention, other group is control (no intervention)
- only difference b/w 2 groups is intervention so any differences can be attributed to intervention
Are all Randomised Control Trials good quality?
no not all equal- must assess quality (Appraise)
What methodology is used to critically appraise RCT?
PEDro database scale
Physiotherapy Evidence Database scale
How does PEDro work?
11 criteria, 10 scored to give total of 10
Explain the steps of appraising Randomised Control Trials:
check word doc`
What question in PEDro is not used to calculate PEDro score in RCT?
- Eligibility criteria specified
What is external validity?
Do the results help in caring for my Px?
What is internal validity?
Are the results valid?
What is statistical significance?
Are the results of value?
What ist he purpose of 1. Eligibility criteria specified?
External validity- are results applicable to Px?
Not used to calculate PEDro score
Do quasi-randomised allocation procedures satisfy randomly allocated criteria?
NO
What is quadi-randomised procedures?
e. g. allocation by surname, birthdate, hospital number
- doesn’t satisfy randomly allocated criteria
Why is it important that assessors are blind?
they can influence the effect size with their bias
Can analysis be done as if participants were in the group they swaped into?
NO- biases the group allocation
- measure as if participant received treatment they were allocated to
What do RCT measure?
average effects of an intervention
- SIZE of intervention (difference in means b/w control and experimental group)
- PRECISION of intervention effect (SD, SE, CI)
What is a type I error
Probability of false positive (falsely rejecting null hypothesis)
- cutoff is p<0.05
What is power of a study?
Ability to detect differences
How can we increase the power of a study?
increasing participants
Why do we want a stronger power of study?
Greater ability to detect differences
Usual convention of power:
80% chance of detecting differences (20% chance of type II error)
What is a Type II error?
probability of falsely accepting null hypothesis
- due to POWER of study wanting 80% chance of detecting differences
- so 20% chance of not detecting differences and falsely accepting null hypothesis
Type I error vs Type II error
Type I: falsely rejecting null hypothesis (b/c p<0.05)
Type II error: falsely accepting null hypothesis (b/c power = 80%)
If we replicate a study with another sample of participants, would we get the same size of intervention effect?
NO (most likely not)
Does the size of the intervention effect of a study measure the size of the intervention effect in a population?
NO
What are Confidence Intervals?
- how much uncertainty is associated with estimate of intervention effect
(i. e. precision/accuracy of estimate) - range of values that true value lies in
What does a Confidence Interval of 95% mean?
we are 95% confident that true intervention effect lies between upper and lower limits of CI
- if you repeated experiment, 95% of intervals computed would contain true population value
RCT 1. Eligibility criteria were specified
- not added to PEDro score
- satisfied if provides list of criteria to determine whos eligible for study
- used for assess if study applied to your Px
RCT 2. Subjects were randomly allocated to groups
participants randomly allocated to group
random not quasi-randomised allocation
- e.g. role of dice - yes
- e.g. based on DOB, surname- NO
RCT 3. Allocation was concealed
all individuals in study unaware of allocation
RCT 4. The groups were similar at baseline regarding the most important prognostic indicators
- this is the aim of randomisation
- present at least 1 measure of severity of condition in each group measured at baseline and we judge that they are similar
- often in Table 1
RCT 5. There was blinding of all subjects
if participants could not know which group they are allocated to
RCT 6. There was blinding of all therapists who administered the therapy?
if you believe that therapist (providing treatment) could not know which group participant is allocated to
RCT 7. There was blinding of all assessors who measured at least one key outcome
if you believe assessor cant know which group the participant is allocated to
RCT 8. Measures of at least one key outcome were obtained from more than 85% of subjects initially allocated
• satisfied if report explicitly states both:
o the number of participants initially allocated to groups
o the number of participants from whom key outcome measures were obtained.
o In trials in which outcomes are measured at several points in time, a key outcome must have been measured in >85% of subjects at one of those points in time.
RCT 9. All subjects for whom outcome measures were available received the treatment or control condition as allocated or, where this was not the case, data for at least one key outcome was analysed by “intention to treat”
satisfied if
o analysis is performed as if participants received the intervention they were allocated to.
o report does not need to mention analysis by intention to treat if it explicitly states that all participants received the intervention as allocated.
RCT 10. Results of between-group statistical comparisons are reported for at least one key parameter
e.g. p value or Confidence interval
RCT 11. Study provides both point measures and measures of variability for at least one key outcome
e.g. SD, SE, CI
