Placebo composition uncertain

January 01, 0001

Placebo composition uncertain

No regulations govern placebo composition. The composition of placebos can influence trial outcomes and merits reporting. The aim of this study by researchers from the US, Canada and the UK was to assess how often investigators specify the composition of placebos in randomized, placebo- controlled trials. 3 reviewers screened titles and abstracts of 4 English-language general and internal medicine journals with high impact factors to identify randomized, placebo-controlled trials published from January 2008 to December 2009. Reviewers independently abstracted data from the introduction and methods sections of identified articles, recording treatment type (pill, injection, or other) and whether placebo composition was stated. Discrepancies were resolved by consensus.

Most studies did not disclose the composition of the study placebo. Disclosure was less common for pills than for injections and other treatments (8.2% v 26.7%; significant).

The researchers concluded: "Placebos were seldom described in randomized, controlled trials of pills or capsules. Because the nature of the placebo can influence trial outcomes, placebo formulation should be disclosed in reports of placebo- controlled trials."

What an interesting idea. We cannot assume they are all the same or inert without knowing their composition.

For the full abstract, click here.

Annals of Internal Medicine 153(8):532-535, 19 October 2010
© 2010 by the American College of Physicians
What's in Placebos: Who Knows? Analysis of Randomized, Controlled Trials. Beatrice A. Golomb, Laura C. Erickson, Sabrina Koperski, Deanna Sack, Murray Enkin and Jeremy Howick. Correspondence to Beatrice Golomb: [email protected]

Category: A. General/Unspecified. Keywords: placebo, analysis of randomized controlled trials, journal watch.
Synopsis edited by Dr Stephen Wilkinson, Melbourne, Australia. Posted on Global Family Doctor 12 November 2010

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