Article

A review and analysis of placebo treatments, placebo effects, and placebo controls in trials of medical procedures when sham is not inert

Stichting (Foundation) for the Study of Traditional East Asian Medicine (STEAM), Amsterdam, The Netherlands.
The Journal of Alternative and Complementary Medicine (Impact Factor: 1.52). 05/2006; 12(3):303-10. DOI: 10.1089/acm.2006.12.303
Source: PubMed

ABSTRACT Researchers examining the efficacy of medical procedures make assumptions about the nature of placebo. From these assumptions they select the sham interventions to be used in their trials. However, placebo is not well defined. A number of definitions are contradictory and sometimes misleading. This leads to problems in sham-controlled studies of medical procedures and difficulties interpreting their results. The author explores some of the contradictory definitions of placebo and assumptions and consequences of these. Principal among these is the assumption that the placebo is inert when it is not, which introduces bias against the tested medical procedures and devices. To illustrate the problem, the author examines the use of sham procedures in clinical trials of the medical procedures surgery and acupuncture in which the sham was assumed to be inert but was not. Trials of surgery and acupuncture should be re-examined in light of this.

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    ABSTRACT: To analyse the impact of placebo effects on outcome in trials of selected minimally invasive procedures and to assess reported adverse events in both trial arms. A systematic review and meta-analysis. We searched MEDLINE and Cochrane library to identify systematic reviews of musculoskeletal, neurological and cardiac conditions published between January 2009 and January 2014 comparing selected minimally invasive with placebo (sham) procedures. We searched MEDLINE for additional randomised controlled trials published between January 2000 and January 2014. Effect sizes (ES) in the active and placebo arms in the trials' primary and pooled secondary end points were calculated. Linear regression was used to analyse the association between end points in the active and sham groups. Reported adverse events in both trial arms were registered. We included 21 trials involving 2519 adult participants. For primary end points, there was a large clinical effect (ES≥0.8) after active treatment in 12 trials and after sham procedures in 11 trials. For secondary end points, 7 and 5 trials showed a large clinical effect. Three trials showed a moderate difference in ES between active treatment and sham on primary end points (ES ≥0.5) but no trials reported a large difference. No trials showed large or moderate differences in ES on pooled secondary end points. Regression analysis of end points in active treatment and sham arms estimated an R(2) of 0.78 for primary and 0.84 for secondary end points. Adverse events after sham were in most cases minor and of short duration. The generally small differences in ES between active treatment and sham suggest that non-specific mechanisms, including placebo, are major predictors of the observed effects. Adverse events related to sham procedures were mainly minor and short-lived. Ethical arguments frequently raised against sham-controlled trials were generally not substantiated. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    BMJ Open 01/2015; 2015;5(e007331):1 - 15. DOI:10.1136/bmjopen-2014-007331 · 2.06 Impact Factor

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