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Volume 355:211-212 July 13, 2006 Number 2
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The Challenge of Subgroup Analyses

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by Lagakos, S. W.
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To the Editor: The Perspective article by Lagakos (April 20 issue)1 was a welcome explication of a contentious topic. Although the article focused on the role of chance and false positive results, it did not discuss another, more pernicious problem — bias. Whenever a subgroup analysis is performed, the randomization of patient characteristics between the treatment group and the control group is no longer necessarily maintained. Consider a subgroup analysis according to sex. The randomization process should ensure, if the sample is large enough, that the treatment and control groups are balanced according to sex. But randomization does not ensure . . . [Full Text of this Article]



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