Health Evidence Bulletins - Wales: Questions to assist with the
critical appraisal of a randomised controlled trial (Type II evidence)
Adapted from the CASP questions (taken from Guyatt et al. Users' guides to the medical literature. II How to use an article about therapy or prevention. Journal of the American Medical Association. 1993; 270: 2598-2601 and 271: 59-63) and Barker, JM. Project for the enhancement of the Welsh Protocols for Investment in Health Gain. Project Methodology. Cardiff: Duthie Library. UWCM, 1996. Egger et al. How important are comprehensive literature searches and the assessment of trial quality in systematic reviews? Health Technology Assessment 2003; 7(1)
A/ What is this trial about and can I trust it?
|1. Is the trial relevant to the needs of the Project?|
|2. Did the trial address a clearly
in terms of:
Was there concealment of
|4. Were all the patients who entered
the trial properly accounted for at its conclusion?
|5. Were patients, health workers and
study personnel 'blind' to treatment?
|6. Were the groups similar at the start
of the trial?
In terms of all the factors that might be relevant to the outcome:
age, sex, social class, life style etc.
|7. Aside from the experimental intervention, were the groups treated equally?|
Is it worth continuing?
B/ What did they find?
|8. How large was the treatment effect?
|9. How precise was the estimate of
the treatment effect?
C/ Are the results relevant locally/to me?
|10. Can the results be
applied to the local population?
Do you think the patients covered by the trial are similar enough to your population? Consider culture, geography etc.
|11. Were all important
If not, does this effect the conclusion(s)?
|12. Is any cost information provided?||N/A|
|13. Accept for further use as Type II evidence?||Refer to Team Leader|
In the Draft Statement Remember to include the relevant target group (age range, sex etc.); the duration of the study, the measured outcomes/benefits with quantitative information if available and whether: 1. Treatment allocation was concealed; 2. An intention-to-treat analysis was carried out (include % follow-up); and 3. The trial was double (or triple) blind.