Critical Appraisal Flashcards
CASP - Critical Appraisal Skills Programme
What are the main steps of assessing an RCT?
- Is study design valid for RCT? e.g population, randomisation
- Was the study methodologically sound?
- What were the results?
- Are the results applicable?
RCT
What is involved in this step
- Is study design valid for for RCT?
Is there a clear defined question - PICO
Population
Intervention
Comparator
Outcomes measured
Randomisation - did this help eliminate bias
Were losses to follow-up and exclusions accounted for
Power calculation undertaken
RCT
What is involved in this step
- Was the study methodologically sound?
Were participants blinded
Were investigators blinded
Were the analysers blinded
Was baseline characteristic of each group similar
Apart from intervention, was each group treated equally
RCT
What is involved in this step
- What were the results?
What outcomes were measured
Any missing/ incomplete data
Were sources of bias identified
P values/ Confidence intervals reported
Were harms reported
Was cost-effectiveness undertaken
RCT
What is involved in this step
- Are the results applicable?
Can the results be applied to your population e.g do you have a similar population in your area
Any significant differences between study population and your population
Does this intervention provide more value to people in your care than existing interventions
Benefits worth the harm/ risk
Diagnostic test study
What are the main steps for analysing this study?
- Screening questions e.g clear population, test
- Conduct and description of testing
- Results
- Applicableness
Diagnostic test study
What is involved in this step
- Screening questions
clear population e.g demographics. But also symtpoms eg respiratory symptoms. Ensure similar populations
appropriate standard used as comparator e.g gold standard
Diagnostic test study
What is involved in this step
- Conduct and description
did all patients get both tests
were test protocols described in detail, to allow replication
Diagnostic test study
What is involved in this step
- Results
Do results report key metrics:
sensitivity
specificity
PPV
NPV
Likelihood ratio
are confidence itnervals given
Diagnostic test study
What is the likelihood ratio
The Likelihood Ratio (LR) is the likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that that same result would be expected in a patient without the target disorder.
LR = probability a person with condition has positive test result divided by probability a person without condition has a positive test result
The LR is used to assess diagnostic tests
They have advantages over sensitivity and specificity because they are less likely to change with the prevalence of the disorder, they can be calculated for several levels of the symptom/sign or test, they can be used to combine the results of multiple diagnostic test and the can be used to calculate post-test probability for a target disorder
LR > 1 means post-test probability is higher than pre-test probability. This means test is useful, as those with the disease are more likely to test positive
LR <1 means post-test probability is less than pre-test probability
In theory, LR tells you if a test is correct. It isn’t used much practically
Diagnostic test study
What is involved in this step
- Applicabiliness
how does study population compare to real life
costs/ resources for applying new test
Systematic review
What steps are involved?
Focussed question - PICO
Population
Intervention
Comparator
Outcomes measured
Search - correct studies e.g RCTs, enough databases
Assess quality of included studies
Results
Applicability
Systematic review
What steps are involved in a literature search?
Look for correct type of papers eg. RCTs?
Do studies selected address the question?
Use enough databases?
Grey literature?
Manual reference searches?
Ask an expert?
Language limitations?
Assessed the quality of included studies?
