Informing participants of allocation to placebo at trial closure: postal survey |
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| Authors: | Zelda Di Blasi Ted J Kaptchuk John Weinman Jos Kleijnen |
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| Affiliation: | 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 |
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| Abstract: | ObjectivesTo 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.DesignPostal survey with a semistructured questionnaire.ParticipantsAll 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.Results45% 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%).ConclusionFurther research is required to examine sensitive ways to communicate treatment information to trial participants. What is already known on this topicInformation is poor on the nature, extent, and effect of informing participants of placebo controlled randomised trials about their treatment allocation at trial closureLess than 50% of participants receiving placebo are informed about their treatment allocationWhat this study addsNo standard procedure is available for informing patients of their treatment arm or of study results at the end of a trialEffective and sensitive ways of communicating treatment allocation to participants are required, as is information on the effects on placebo responders |
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