Paper

Informing participants of allocation to placebo at trial closure: postal survey

BMJ 2002; 325 doi: 10.1136/bmj.325.7376.1329 (Published 7 December 2002)
Cite this as: BMJ 2002;325:1329
  1. Zelda Di Blasi, PhD student (zdb1{at}york.ac.uk)a,
  2. Ted J Kaptchuk, assistant professorb,
  3. John Weinman, professorc,
  4. Jos Kleijnen, directord
  1. aDepartment of Health Sciences, University of York, York YO10 5DD
  2. bOsher Institute, Harvard Medical School, 401 Park Drive, Boston, MA 02215, USA,
  3. cUnit of Psychology, Guy's, King's, and St Thomas's School of Medicine, London SE1 9RT,
  4. dNHS Centre for Reviews and Dissemination, University of York, York YO10 5DD
  1. 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

    • Funding None.

    • Conflict of interest None declared

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