Intended for healthcare professionals

Endgames Statistical Question

Double dummy trials

BMJ 2011; 343 doi: (Published 16 November 2011) Cite this as: BMJ 2011;343:d7294
  1. Philip Sedgwick, senior lecturer in medical statistics
  1. 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London, UK
  1. p.sedgwick{at}

Researchers evaluated the efficacy of quetiapine and of rivastigmine in the treatment of agitation in people with dementia in institutional care. Little research had been undertaken in the use of these drugs to treat this condition. A randomised, double blind, double dummy, placebo controlled trial was performed.1 The outcome measures included agitation and cognitive performance at baseline, at six weeks, and at 26 weeks. A total of 93 patients were randomised to quetiapine, rivastigmine, or placebo.

The researchers reported that, when compared with placebo, neither quetiapine nor rivastigmine was effective …

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