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Published on: September 20, 2019
Informing participants of allocation to placebo at trial closure: postal survey
Zelda Di Blasi1, Ted J Kaptchuk, John Weinman
1Department of Health Sciences, University of York, York YO10 5DD. zdb1@york.ac.uk
Objectives:
To assess whether and how investigators of placebo controlled randomised trials inform participants of their treatment allocation at trial closure and to assess barriers to feedback.
Design:
Postal survey with a semistructured questionnaire.
Participants:
All investigators who published a placebo controlled randomised trial in 2000 in five leading medical journals, and a random sample of 120 trials listed in the national research register database.
Main Outcome Measures:
Number of investigators who informed participants of their treatment allocation at trial closure, methods for delivering the information, and barriers to unmasking treatment.
Results:
45% of investigators informed either all or most participants of their treatment allocation, and 55% did not inform any participant or only informed those who asked. The main reasons for not informing participants were that the investigators never considered this option (40%) or to avoid biasing results at study follow up (24%).
Conclusion:
Further research is required to examine sensitive ways to communicate treatment information to trial participants.
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