Monitoring clinical trials

BMJ 2001; 323 doi: https://doi.org/10.1136/bmj.323.7326.1424 (Published 15 December 2001) Cite this as: BMJ 2001;323:1424

Dissemination of decisions on interim analyses needs wider debate

  1. Sheila M Bird, senior statistician (sheila.bird@mrc-bsu.cam.ac.uk)
  1. MRC Biostatistics Unit, Cambridge CB2 2SR
  2. CTSU, Radcliffe Infirmary, Oxford OX2 6HE
  3. Saionara, 31 Regent Street, Rowhedge, Colchester CO5 7EA
  4. School of Information Technology, Business Faculty, Auckland University of Technology, Private Bag 92006, Auckland 1020, New Zealand
  5. School of Health Sciences, Deakin University, Burwood, VIC 3125, Australia
  6. 76 The Crescent, Belmont, Surrey SM2 7BS

    EDITOR—Lilford et al make a case that interim analyses from randomised trials should be shared with participants and doctors and patients.1 These analyses should be shared for the sake of freedom of information and properly informed consent, as a counterweight to paternalism, for the better public understanding of uncertainty, and regardless of drug regulatory or financial considerations.1 But the authors stop short of suggesting how to evolve the design of randomised controlled trials so that future patients and their doctors, in the light of emerging information, might have more choice than between 50:50 randomisation to treatments A and B versus self determination to receive treatment A or B.

    The consumer principle of randomisation, which to my knowledge has not been implemented since its enunciation in 1994,2 offers doctors and patients the option of choosing one of three randomisation ratios, such as 30:70 (uncertain or idiosyncratic preference for B, yet willing to be randomised if allocation is weighted in favour of B), 50:50 (absolute uncertainty or complete altruism), or 70:30 (uncertain or idiosyncratic preference for A, yet willing to be randomised if allocation is weighted in favour of A).

    Importantly, the choice of randomisation strata is an additional patient covariate that was not previously available; comparison between treatments is unbiased within the chosen randomisation stratum; and how the choice of randomisation stratum drifts after disclosure of interim data is a measure of how those data were assimilated by future patients and their doctors. Data monitoring committees might even decide to close one of the randomisation strata, such as closing down 30:70 randomisation if the interim data pointed moderately convincingly in favour of A.

    Not only should there be wider debate about the dissemination to doctors and patients of data monitoring committees' decisions on interim analyses but there should …

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