Estimating the causal effect of randomization versus treatment preference in a doubly randomized preference trial
Sue M Marcus1, Elizabeth A Stuart, Pei Wang
1Department of Psychiatry, Columbia University, New York State Psychiatric Institute, 1051 Riverside Drive, New York, NY 10040, USA. smarcus@pi.cpmc.columbia.edu
Psychological Methods
|May 9, 2012
Summary
Doubly randomized preference trials (DRPT) bridge the gap between randomized trials and real-world effectiveness. Preference for treatment, rather than randomization, showed a moderate benefit in a psychology study.
Area of Science:
- Clinical Trials Methodology
- Psychology Research Methods
- Causal Inference
Background:
- Randomized clinical trials (RCTs) offer high internal validity but limited generalizability to real-world settings.
- Patient preference for treatment can influence compliance and engagement, complicating RCT result interpretation.
- Existing designs struggle to disentangle the effects of randomization from treatment preference.
Purpose of the Study:
- To introduce and validate the doubly randomized preference trial (DRPT) design.
- To estimate the causal effect of randomization versus treatment preference.
- To assess the generalizability of RCT findings in real-world conditions.
Main Methods:
- The DRPT involves initial randomization to either randomized or choice assignment.
- Participants in the choice group select their preferred treatment.
- Potential outcomes framework and propensity score matching were used for analysis.
Main Results:
- The DRPT allows unbiased estimation of the causal effect of randomization versus preference.
- A DRPT in introductory psychology demonstrated a small to moderate benefit of treatment preference over randomization for mathematics training.
- This suggests preference impacts outcomes, challenging pure randomization generalizability.
Conclusions:
- The DRPT is a valuable hybrid design for evaluating treatment effectiveness in real-world contexts.
- Understanding the impact of patient preference is crucial for improving treatment generalizability.
- Future research should utilize DRPTs to enhance the applicability of clinical trial findings.
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