8. Questioning the Methodological Superiority of “Placebo” over “Active” Controlled Trials

  1. Jeremy Howick1,2

Published Online: 23 MAR 2011

DOI: 10.1002/9781444342673.ch8

The Philosophy of Evidence-Based Medicine

The Philosophy of Evidence-Based Medicine

How to Cite

Howick, J. (2011) Questioning the Methodological Superiority of “Placebo” over “Active” Controlled Trials, in The Philosophy of Evidence-Based Medicine, Wiley-Blackwell, Oxford, UK. doi: 10.1002/9781444342673.ch8

Author Information

  1. 1

    Centre for Evidence-Based Medicine, Department of Public Health and Primary Care, University of Oxford, Oxford, UK

  2. 2

    Department of Science and Technology Studies, University College London, London, UK

  1. A slightly shorter version of this chapter was published in American Journal of Bioethics 2009;9:34–48.

Publication History

  1. Published Online: 23 MAR 2011
  2. Published Print: 8 APR 2011

ISBN Information

Print ISBN: 9781405196673

Online ISBN: 9781444342673

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Keywords:

  • methodological superiority of “placebo” - over “active” controlled trials;
  • placebo-controlled trials (PCTs) - reliable knowledge about therapeutic effects of medical treatments;
  • problems, with assay sensitivity arguments against ACTs - assay sensitivity, trials to distinguish differences between experimental and control therapies;
  • first assay sensitivity argument against ACTs - problematic in two ways, PCTs lacking assay sensitivity;
  • variable placebo effects in trials - constant experimental treatment effects, assay sensitivity problem for PCTs;
  • justification for non-inferiority trials - treatments, real advance without offering superiority on primary outcome;
  • second assay sensitivity argument - ability of a trial to distinguish, effective and less effective (placebo or not) treatments;
  • differences, between superiority and non-inferiority trials - using confidence intervals;
  • PCTs, measure of absolute effect size - additivity, placebo and non-placebo components adding rather than interacting, and placebo controls being legitimate;
  • extended balanced placebo design - study of effects of nicotine gum

Summary

This chapter contains sections titled:

  • Epistemological foundations of the ethical debate over the use of placebo-controlled trials

  • Problems with the assay sensitivity arguments against ACTs

  • Problems with the first assay sensitivity argument against ACTs

  • The second assay sensitivity argument

  • Challenging the view that PCTs provide a measure of absolute effect size

  • Questioning the claim that PCTs require smaller sample sizes

  • Conclusion: a reassessment of the relative methodological quality of PCTs

  • Appendix: more detailed explanation of why the second assay sensitivity argument fails