When the right dose goes wrong

It must gall to have performed a controlled clinical trial for a year only to find at the end that your physics department had adjusted the active laser such that it did not perform as planned.

The trial by Tumilty et al (TITLE: Clinical effectiveness of low-level laser therapy as an adjunct to eccentric exercise for the treatment of Achilles’ tendinopathy: a randomized controlled trial) set out to deliver twelve treatments of 100mW/cm2 of 810nm laser for 30 seconds to 6 points (3J per point) on the Achilles tendon over a 4 week period, but something went wrong and the treatment failed to have any significant effect over placebo.

What went wrong: The university physics dept had been asked to adjust the 810nm 100mW, 2.5W/cm2 power density to 100mW/cm2. They achieved the 100mW/cm2 by expanding the beam, but unfortunately they also decided to reduce the aperture to 0.07cm2. This had two unfortunate effects, the 100mW beam became reduced to 7mW and the beam did not adequately cover the pathology. So only 0.21J was delivered and only a tiny part of the pathology was treated.

WALT guidelines say 2-3 points should be treated with 8 Joules, the beam power density should not exceed 100mW/cm2 and irradiation should cover most of the pathological tissue. So this trial was a long way short of the recommended energy and it did not adequately cover the pathology.

Unfortunately these errors are hard to find in the paper. The “method’ reported states that the laser was 100mW, the power density was 100mW/cm2, treatment time was 30 seconds, giving a dose of 3J per point. It is only late in the “discussion” that the errors are presented.

Throughout the paper it is implied that the correct parameters were used and the WALT Guidelines were adhered to, but that is not true. It is not apparent in the paper that the tube had a cap at the end and that it had a 0.07cm2 hole drilled in it. Our initial presumption was that he tube was an empty tube, it was only after correspondence with the authors that we learned these extra facts.

What worries me is that this trial will be used in systematic reviews or as evidence against LLLT or the WALT guidelines

Don’t make these mistakes on your patients or in research, register for a THOR training course and learn about parameters, dose calculations and treatment methods, especially if you intend to run a clinical trial and maybe contact me to help get your trial parameters right,

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About James Carroll

Founder and CEO at THOR Photomedicine Ltd. About THOR
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1 Response to When the right dose goes wrong

  1. Jan Tunér says:

    About mucositis
    Alas. you are not the only one. I was twice invited to the University hospital of Uppsala to speak about lllt for mucositis. They invited me because I had pretreated (and supplied home laser to use during radiation periods) some of their patients, and these did not develop much mucositis. So I presented the 1999 Bensadoun phase III paper and other papers, rather heavy ammo. They admitted that mucositis was a great problem and that there was no effective method to reduce it. I asked about the cost to keep one single patient one additional day hospitalised due to mucositis and it was quite clear that a laser equipment would very soon be profitable. Did I ever hear from them again? Your guess!
    Re Tumilty: A sincere description, what a waste of time and money! Could I add it to the next issue of LaserAnnals? Due August.
    Jan

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