Evidence-based Practice Flashcards
What is the aim of critical appraisal?
To understand strengths, weaknesses and potential for bias in research before you apply it
List 4 considerations used to determine if evidence is valid
- Is it clinically significant?
- Is it clinically important?
- Is the evidence applicable
- Is the evidence relevant?
What are the 4 tools in the Critical Appraisal Skills Program (CASP)?
- Systematic Reviews
- RCTs
- Case Control Studies
- Cohort Studies
List 2 screening questions you should ask when appraising systematic reviews
- Did the review address a clearly focused question?
- Did the author look for the right type of papers?
Should answer YES to both
List 8 detailed questions you should ask when appraising the evidence from systematic reviews
- Were all important, relevant studies included?
- Did the author do enough to assess quality of included studies?
- If results were combined, was it reasonable to do so?
- What were overall results of the review?
- How precise were results?
- Do results apply to population?
- Were all important outcomes considered?
- Are the benefits worth the harm and cost?
What does the appraisal method RAMMbo stand for?
R - Recruitment
A - Allocation
M - Maintenance
M - Measurement
b - blind testing
o - objective and standardised measures
Give 1 question you should ask when appraising a models Recruitment (RAMMbo)?
- Are Ps representative of population?
Give 2 question you should ask when appraising a models Allocation (RAMMbo)?
- Was the assignment to treatments randomised?
2. Were the groups similar at the start of the trial?
Give 2 question you should ask when appraising a models Maintenance (RAMMbo)?
- Were the individuals in the groups treated equally?
2. Were the outcomes ascertained and analysed for most Ps?
Give 2 question you should ask when appraising a models Measurements (RAMMbo)?
- Were the Ps and clinicians blinded?
2. Were measurements objective and standardised?
What is the CONSORT Statement?
An evidence based, minimum set of recommendations for reporting RCTs.
A 25 item checklist
What does CONSORT stand for?
CONsolidated Standards Of Reporting Trials
Is statistical significance the same as clinical significance?
No
What is clinical significance?
The practical importance of a treatment effect
Whether it has a real genuine, palpable, noticeable effect on daily life
When is a treatment effect clinically relevant?
A small therapeutic benefit may be important for a highly fatal disease, but may not be enough to justify a new intervention in a disease with a good prognosis
What does clinical importance require?
A substantial change in an outcome that matters
What calculations can you use to ascertain clinical significance?
- Event rare
- Absolute and relative rate
- Number needed to treat
What is the Absolute Risk of a disease?
Your own risk of developing the disease over a period of time
Expressed as 1 in 10, 10%, or 0.1 risk
What is Relative Risk?
Used to compare the risk in two different groups of people
Eg. Smokers have a higher risk of lung cancer relative to non smokers
What is the Event Rate?
The proportion of people in control/treatment conditions of an experiment who experience a particular event (response to drug)
Name the 2 types of Event rates
- CER- Control event rate
2. EER - Experimental Event rate
What is Number Needed to treat?
The number you need to treat to prevent a bad outcome
What is the Absolute Risk Reduction (ARR)?
The AAR is the difference between the event rates in the 2 groups or the size difference between 2 treatments
What does the AAR tell you?
The AAR tells you the size of the treatment effect
How do you calculate AAR or Absolute Risk Reduction?
CER - EER
(Control event rate minus experimental event rate)
Difference between event rates in the 2 groups
If 20% of patients die with no treatment (A) and 15% die with treatment (B), what is the Absolute Risk Reduction?
5%
CER-EER
0.20-0.15 =0.05 or 5%
This means that for every 100 patients enrolled in the treatment group about 5 deaths would be prevented
What is another way of expressing the Absolute Risk Reduction?
The Number Needed to treat NNT
The number of patients that need to be treated in order to have an impact on 1 person to prevent additional bad outcomes
How do you calculate the Number Needed to Treat NNT?
NNT= 1/ARR
Number Needed to Treat = 1 divided by the Absolute Risk Rate
What is the Number Needed to Treat in a clinical trial of a drug preventing migraines if 2 out of 100 people taking the drug experience migraines (2%) compared to 4 out of 100 taking a placebo?
ARR = CER- EER =0.02
NNT = 1/ARR = 1/0.02 = 50
The number you need to treat for 1 person to benefit is 50
What is Relative Risk Reduction RRR?
RRR is the difference in event rates between 2 groups expressed as a proportion of the event rate in the untreated group
The relative or proportional difference
What is the Relative Risk Reduction if 20% of patients die with no treatment A and 15% die with treatment B. ?
There is a 5% Absolute Risk Reduction with treatment B. The Relative Risk Reduction is 25%
RRR = (CER - EER)/CER
= (0.2 - 0.15)/0.2 = 25
This means that the disease was reduced by 25% in the treatment group compared with the Control group
What are the similarities between Absolute Risk Reduction ARR and Relative Risk Reduction RRR?
Both calculations explain the same difference BUT in different ways
What are the differences between Absolute Risk Reduction ARR and Relative Risk Reduction RRR?
ARR explains the simple difference between rates
RRR describes the Relative or proportional difference
What is the Odds Ratio (OR)?
Odds Ratio is a measure of association between an exposure and an outcome.
The OR represents the odds that an outcome will occur given a particular exposure compared to the odds of the outcome occurring in the absence of that exposure
What is the Odds Ratio OR if 100 patients with lung cancer and 100 patients without lung cancer were recruited into a study and questioned about their tobacco use over the past 20 years. 90 with lung cancer and 10 without reported smoking?
OR= exposed to smoking & have cancer / exposed to smoking and don’t have cancer
Calculate cross product
OR = 90x90/10x10=81
If you have lung cancer you’re 81 times more likely to have smoked than if you don’t have cancer
What is the standard effect size?
Provides an indication of the size of treatment effects
is the magnitude sufficient to be of practical relevance?
What calculation is used to find effect size?
Cohen’s d
Cohen’s d = (M1-M2)/SDpooled
Take the mean difference between 2 treatments and divide by the pooled variance
How do you interpret standard effect size?
- 2 = small
- 5 = moderate
- 8 = large
List 3 ways to assess whether results apply to your clients
- Assessment of their individual baseline risk
- Judgment about whether the evidence can be extrapolated to your client
- Understanding of factors that may increase the benefits or harm their experience
List 4 considerations when applying evidence results
- Do the results apply to my client?
- What are my clients values and preferences?
- Can the practice be implemented in this setting?
- How can I help my client make a decision?
What are the benefits of qualitative research?
Provides guidance in deciding whether findings apply to clients
Determines how people feel about things and what their experiences were
What is the efficacy of a treatment determined by?
Clinical trials which many variables are carefully controlled to demonstrate that the relationship between the treatment and outcome are relatively ambiguous
What do efficacy studies emphasise?
Internal validity of the experiment
- controlling types of Ps
- using manuals for standardisation
- training and monitoring therapists
- controlling number of treatment sessions
- random assignment and blind testing
What do effectiveness studies seek to examine?
The outcomes of interventions under circumstances that are similar to the real world (external validity)
