Different types of trial design. and implications for reporting Alison Wearden. Uncontrolled trials. Test feasibility and acceptability of an intervention, and whether there are adverse effects May allow preliminary examination of mechanisms of change
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Different types of trial design
and implications for reporting
From D. Wang & A Bakhai (Eds) Clinical Trials. A Practical Guide
to Design, Analysis and Reporting. 2006, Remedica: London, pp 57
Types of CONTROLLED TRIALS
What factors do you need to take into account choosing a trial type and design?
What is your research question?
Are there ethical constraints?
Where might you want to publish your trial?
Does this intervention work in people who receive it under carefully controlled conditions? How does it work?
What would be the outcome if this intervention were implemented in usual clinical practice?
See Zwarenstein et al., 2008, BMJ, 337, 1223-6
A or control
Simple, parallel design
Is A better than control?
Are effects of A and B
additive or interactive?
A & B each controlled
(Unlikely – useful with small samples)
A THEN B or
B THEN A
Boutron et al., 2008, Ann Int Med, 148, 295-309
Zwarenstein et al., 2008, BMJ, 337, 1223-6
Piaggio et al., 2006, JAMA,295,1152-1160