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Ann Rheum Dis 2004;63:1368-1371 doi:10.1136/ard.2003.014035
  • Hypothesis

How the type of risk reduction influences required sample sizes in randomised clinical trials

  1. K Bruynesteyn,
  2. A Wanders,
  3. R Landewé,
  4. D van der Heijde
  1. Department of Internal Medicine, Division of Rheumatology, University of Maastricht, Maastricht, The Netherlands
  1. Correspondence to:
    Professor D van der Heijde
    Department of Internal Medicine, Division of Rheumatology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands; dhesint.azm.nl
  • Accepted 23 May 2004
  • Published Online First 1 July 2004

Abstract

To increase change between groups, randomised clinical trials (RCT) often include patients with high risk for a particular outcome, by inclusion criteria that select predictors for that outcome. This increases the statistical power, and fewer patients are required for that RCT. The way in which patient selection influences the power, and thus sample size required, depends on how an intervention reduces the individual risk: by an absolute or relative risk reduction model.

Footnotes

    Responses to this article

    • Should patients with medium risk of disease progression really be avoided in clinical trials?
      • Jane S Angwin,
      • Michael Binks, Michael F. James
      Ann Rheum Dis published online January 10, 2005

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      1. ard.2003.014035v1
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