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©Critical Appraisal Skills Programme (CASP) Randomised Controlled Trials Checklist 31.05.13
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11 questions to help you make sense of a trial
How to use this appraisal tool
Three broad issues need to be considered when appraising the report of a randomised controlled
trial:
Are the results of the trial valid? (Section A)
What are the results? (Section B)
Will the results help locally? (Section C)
The 11 questions on the following pages are designed to help you think about these issues
systematically.
The first two questions are screening questions and can be answered quickly. If the answer to both is
yes, it is worth proceeding with the remaining questions.
There is some degree of overlap between the questions, you are asked to record a yes, no or can’t
tell to most of the questions. A number of prompts are given after each question. These are
designed to remind you why the question is important. Record your reasons for your answers in the
spaces provided.
There will not be time in the small groups to answer them all in detail!
These checklists were designed to be used as educational tools as part of a workshop
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©Critical Appraisal Skills Programme (CASP) Randomised Controlled Trials Checklist 31.05.13
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(A) Are the results of the trial valid?
Screening Questions
1. Did the trial address a clearly focused issue? Yes Can’t tell No
Consider: An issue can be ‘focused’ In terms of
The population studied
The intervention given
The comparator given
The outcomes considered
2. Was the assignment of patients to treatments Yes Can’t tell No
randomised?
Consider:
How was this carried out, some methods
may produce broken allocation concealment
Was the allocation concealed from researchers?
Is it worth continuing?
©Critical Appraisal Skills Programme (CASP) Randomised Controlled Trials Checklist 31.05.13
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Detailed questions
3. Were patients, health workers and study Yes Can’t tell No
personnel blinded?
Consider:
Health workers could be; clinicians, nurses etc
Study personnel – especially outcome assessors
4. Were the groups similar at the start of the trial? Yes Can’t tell No
Consider: Look at
Other factors that might affect the outcome such as age,
sex, social class, these may be called baseline characteristics
5. Aside from the experimental intervention, Yes Can’t tell No
were the groups treated equally?
©Critical Appraisal Skills Programme (CASP) Randomised Controlled Trials Checklist 31.05.13
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6. Were all of the patients who entered Yes Can’t tell No
the trial properly accounted for at its
conclusion?
Consider:
Was the trial stopped early?
Were patients analysed in the groups to which
they were randomised?
(B) What are the results?
7. How large was the treatment effect?
8. How precise was the estimate of the
treatment effect?
Consider:
What outcomes were measured?
Is the primary outcome clearly specified?
What results were found for each outcome?
Is there evidence of selective reporting of
outcomes?
Consider:
What are the confidence limits?
Were they statistically significant?
©Critical Appraisal Skills Programme (CASP) Randomised Controlled Trials Checklist 31.05.13
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(C) Will the results help locally?
9. Can the results be applied in your context? Yes Can’t tell No
(or to the local population?)
Consider:
Do you have reason to believe that your population
of interest is different to that in the trial
If so, in what way?
10. Were all clinically important outcomes Yes Can’t tell No
considered?
Consider:
Is there other information you would like to have seen?
Was the need for this trial clearly described?
11. Are the benefits worth the harms and costs? Yes Can’t tell No
Consider:
Even if this is not addressed by the trial,
what do you think?
©Critical Appraisal Skills Programme (CASP) Randomised Controlled Trials Checklist 31.05.13
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