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Evidence-Based Complementary and Alternative Medicine
Volume 5 (2008), Issue 4, Pages 383-389

Blinding Techniques in Randomized Controlled Trials of Laser Therapy: An Overview and Possible Solution

1Department of General Practice, University of Melbourne, 200 Berkeley Street Carlton 3053, Victoria, Australia
2Private Medical Practice, NSW, Australia

Received 1 April 2006; Accepted 9 March 2007

Copyright © 2008 Ian Relf et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Low-level laser therapy has evidence accumulating about its effectiveness in a variety of medical conditions. We reviewed 51 double blind randomized controlled trials (RCTs) of laser treatment. Analysis revealed 58% of trials showed benefit of laser over placebo. However, less than 5% of the trials had addressed beam disguise or allocation concealment in the laser machines used. Many of the trials used blinding methods that rely on staff cooperation and are therefore open to interference or bias. This indicates significant deficiencies in laser trial methodology. We report the development and preliminary testing of a novel laser machine that can blind both patient and operator to treatment allocation without staff participation. The new laser machine combines sealed preset and non-bypassable randomization codes, decoy lights and sound, and a conical perspex tip to overcome laser diode glow detection.