Informing participants of allocation to placebo at trial closure: postal survey
BMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7376.1329 (Published 07 December 2002) Cite this as: BMJ 2002;325:1329
- Zelda Di Blasi, PhD student (zdb1{at}york.ac.uk)a,
- Ted J Kaptchuk, assistant professorb,
- John Weinman, professorc,
- Jos Kleijnen, directord
- aDepartment of Health Sciences, University of York, York YO10 5DD
- bOsher Institute, Harvard Medical School, 401 Park Drive, Boston, MA 02215, USA,
- cUnit of Psychology, Guy's, King's, and St Thomas's School of Medicine, London SE1 9RT,
- dNHS Centre for Reviews and Dissemination, University of York, York YO10 5DD
- aCorrespondence to: Z Di Blasi
Abstract
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.
Footnotes
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Funding None.
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Conflict of interest None declared