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Energized Joints? Bracelets for OA
Abstract & Commentary
By Russell H. Greenfield, MD, Editor
Synopsis: Results of this small double-blind RCT suggest that neither magnetic nor copper bracelets have a place in the treatment of osteoarthritis. These findings contradict those of a few other studies, but almost all suffer from small sample size and other methodological flaws. The lack of sound data regarding such therapy, however, has done little to dampen the enthusiasm of consumers hoping to realize symptom relief.
Source: Richmond SJ, et al. Therapeutic effects of magnetic and copper bracelets in osteoarthritis: A randomized placebo-controlled crossover trial. Complement Ther Med 2009; 17:249-256.
The authors of this randomized, double-blind, placebo-controlled crossover trial sought to determine whether a specific type of commercially available magnetic wrist strap was effective in reducing symptoms in people with osteoarthritis (OA). Potential subjects were those older than age 40 years with documented OA who were taking pain medication (either NSAIDs or opioids). They were recruited from general practices in both rural and urban areas of Yorkshire, United Kingdom, following review of their medical records and a home interview. A total of 300 people were initially approached regarding study participation, of which 45 made up the sample.
Subjects were then randomized to one of four 4-week treatment sequences, each associated with a distinct phase of treatment during which a specific device was employed. The devices were:
A standard MagnaMax® wrist strap (the experimental device) consisting of two plastic-coated permanent neodymium magnets forming a single 23 mm insert attached to a leather strap and worn directly against the skin. Testing prior to randomization showed the average surface magnetic field to be 201 mT.
An attenuated MagnaMax wrist strap, deemed the placebo, which appeared identical to the experimental wrist strap, but possessed a significantly weaker surface magnetic field of 45 mT. These straps would, for example, adhere to a refrigerator door, thus helping to maintain blinding.
A demagnetized MagnaMax wrist strap (dummy) that also appeared identical to magnetic wrist straps, but were non-magnetic, and thus did not attract metal. The researchers believed most participants would be able to recognize this strap as inactive, a dummy device.
A plain copper bracelet as sold by local pharmacies, also deemed a placebo, and with no magnetic properties.
The devices were distributed to the participants in sealed boxes that were labeled only with the order for distribution and study ID number. The devices were to be worn at least 8 hours of every day over the course of the trial, and each subject acted as her/his own control. Follow-up took place at the end of each of the four trial phases.
At trial's end, following one primary and eight secondary analyses, it was determined that subjects experienced pain relief with the experimental device, as well as with the attenuated and the demagnetized wrist straps, but tended to get somewhat worse with the copper bracelet. The reported changes in pain were small and essentially inconsequential, and no statistically significant differences between the four groups were identified. The findings were similar for measures of stiffness (WOMAC B), physical function (WOMAC C), and medication use as quantified from subjects' diaries. One finding of interest, however, was a statistically significant improvement with the true magnetic wrist strap (experimental device) on the PRI sensory pain subscale. No significant adverse events due to use of any of the devices occurred.
The authors conclude that both magnetic and copper bracelets are generally ineffective for management of the pain, stiffness, and physical impairments frequently seen with OA, and that reported benefits are likely a reflection of the placebo effect.
The popular use of magnetic bracelets continues to grow (more than $5 billion in annual sales), rivaled only, it seems, by the growth in claims of therapeutic benefit that appear in associated marketing materials. Many people profess to have benefited from the use of these bracelets, and a small number of studies suggests the potential for benefit in certain painful conditions. Keep in mind, however, that the total number of magnet therapy trials and subjects studied is very small. Keep in mind, too, that magnet therapy, while easily applied and without known significant side effects, can be a very expensive undertaking, and that a wide variety of products are available to the public.
Confidence in the results of this trial is lessened by the small sample size, testing of magnetic strength only at time of randomization, and determination of compliance by self-report. These are significant shortcomings, to be sure, but the study was otherwise well done. There was little attrition and very few data were lost, significant steps were taken to maintain blinding, and intention-to-treat analysis was employed. While some might suggest that the duration of the four phases of treatment was brief, other trials suggest that when magnet therapy is effective the relief is almost immediate.
Previous studies on static magnet therapy suggest that when therapeutic benefits are seen they occur only with strongly magnetized bracelets and not with weakly magnetized ones (under 50 mT), so the attenuated wrist strap may be a reasonable placebo. The wearing of copper bracelets for pain relief in OA has been even less well studied than magnetic bracelet use in this setting. As the authors point out, copper bracelets might be viewed as a valid placebo in light of data suggesting that while dermal absorption may occur with the wearing of such bracelets there is no significant pain relief associated with their use. Still, a large number of patients swear by their effectiveness, and they may not be sharing that information with us unless we can discuss the science behind the therapy ... non-judgmentally.
We practitioners are often dubious of the claims made by purveyors of magnet and copper bracelets, often with good reason, and rarely employ them, but a growing population of people will be faced with the challenges of OA in the coming years. They have read about the shortcomings of NSAIDs, they are fearful about losing their independence, they want to avoid surgical intervention, and they are willing to try anything that might be safe and effective. The results of this trial are by no means definitive, but they can be shared with our patients when the question of magnet therapy comes up, as it will if our patients feel comfortable with us. We can quote from the small amount of existing data, let them know that scientific investigation into magnet therapy is still in its infancy and that existing trials have provided conflicting results, be honest regarding our concerns or positive experience with such therapy, and confidently state that use of these bracelets should not be dangerous to them. We need also share, however, that identifying credible manufacturers and reasonably priced products remains a challenge.