- © 2008 Canadian Medical Association
The appropriateness of controls is often neglected in systematic reviews of complementary therapies. In their systematic review and meta-analysis of static magnets for reducing pain, Max Pittler and colleagues correctly used the appropriateness of a trial's control as a criterion for including the trial in their analysis.1
However, for trials that used a weak magnet as their control, Pittler and colleagues failed to specify the maximal strength of the magnetic field that they felt was appropriate for controls, and they did not justify their choice with references to the published literature. They mentioned that it is assumed that magnets must have a strength of 30 mT or greater for therapeutic benefit, but this value was cited from one of the reviewers' own articles and did not appear to be specific to the present study. Such information could be very useful for future studies in this area, especially given the authors' conclusion that “the ideal magnet strength and treatment duration are unclear.”1 Assessing the trials the reviewers had excluded on the basis of the relative strengths of the placebo and test magnets might have had an impact on the outcomes reported.
Footnotes
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Competing interests: None declared.
REFERENCE
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