BMJ 1996;313:1550 (14 December)

Letters

Relation between treatment benefit and underlying risk in meta-analysis

Standard of "label invariance" should not be abandoned

EDITOR,--Stephen J Sharp and colleagues' discussion of the dangers of attempting to compare treatment benefit with underlying risk in meta-analyses of placebo controlled trials of a presumed active treatment is excellent in two respects.1 Firstly, the authors clearly show a point that I have made--that when the difference in mean observed outcome between groups is related to the mean outcome in the placebo group then a spurious correlation is induced.2 Secondly, they make the important point that it is more relevant to establish the relation between baseline characteristics of the patient and the treatment effect: after all, the prescribing doctor can assess the patient when he or she presents but does not know what the placebo outcome would be.

I am not encouraged by the authors' discussion of the second of the three methods they consider (comparing difference with average). They seem . . . [Full text of this article]


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Relevant Article

The relation between treatment benefit and underlying risk in meta-analysis
Stephen J Sharp, Simon G Thompson, and Douglas G Altman
BMJ 1996 313: 735-738. [Extract] [Full Text]

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