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Exploratory randomized controlled trial evaluating the impact of a waiting list control design
John A Cunningham1, Kypros Kypri, Jim McCambridge
1Centre for Mental Health Research, the Australian National University, Canberra, Australia. john.cunningham@anu.edu.au.
BMC Medical Research Methodology
|December 10, 2013
Summary
Waiting list control designs in behavioral research may inflate intervention effects. This study found potential overestimation, suggesting careful assessment of this threat to valid inference in trials.
Area of Science:
- Psychology
- Behavioral Science
- Clinical Research Methodology
Background:
- Waiting list control designs are common in psychological and behavioral intervention research.
- These designs may artificially inflate intervention effect estimates.
- This study explores this potential bias in problem drinker interventions.
Purpose of the Study:
- To test the proposition that waiting list control designs inflate intervention effect estimates.
- To investigate the impact of waiting list control conditions on brief interventions for problem drinkers.
Main Methods:
- An exploratory randomized controlled trial with 185 participants.
- Participants received a brief personalized feedback intervention.
- Random allocation to either immediate intervention or a four-week waiting list control group.
Main Results:
- 157 participants (85%) completed the 4-week follow-up.
- A between-group difference was observed in one of four outcomes (safe drinking guidelines).
- An interaction showed that participant change was arrested in those ready to change and assigned to the waiting list.
Conclusions:
- Trials using waiting list controls may overestimate treatment effects.
- The extent of bias likely varies across different study populations.
- Waiting list controls should be used cautiously, with careful assessment of the threat to valid inference.
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