Randomised controlled trial of magnetic bracelets for relieving pain in osteoarthritis of the hip and knee

doi:10.1136/bmj.329.7480.1450

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Tim Harlow, general practitioner (timharlow{at}eclipse.co.uk)1,
Colin Greaves, research fellow2,
Adrian White, senior research fellow3,
Liz Brown, research assistant4,
Anna Hart, statistician5,
Edzard Ernst, professor of complementary medicine4

¹ College Surgery, Cullompton, Devon EX15 1TG
² Peninsula Medical School (Primary Care), Exeter EX2 5DW
³ Peninsula Medical School, Tamar Science Park, Plymouth PL6 8BX
⁴ Peninsula Medical School (Complementary Medicine), Exeter EX2 4NT
⁵ Lancashire School of Health and Postgraduate Medicine, University of Central Lancashire, Preston PR1 2HE

Correspondence to: T Harlow, Hospiscare, Dryden Road, Exeter EX2 5JJ

Abstract

Objective To determine the effectiveness of commercially available magnetic bracelets for pain control in osteoarthritis of the hip and knee.

Design Randomised, placebo controlled trial with three parallel groups.

Setting Five rural general practices.

Participants 194 men and women aged 45-80 years with osteoarthritis of the hip or knee.

Intervention Wearing a standard strength static bipolar magnetic bracelet, a weak magnetic bracelet, or a non-magnetic (dummy) bracelet for 12 weeks.

Main outcome measures Change in the Western Ontario and McMaster Universities osteoarthritis lower limb pain scale (WOMAC A) after 12 weeks, with the primary comparison between the standard and dummy groups. Secondary outcomes included changes in WOMAC B and C scales and a visual analogue scale for pain.

Results Mean pain scores were reduced more in the standard magnet group than in the dummy group (mean difference 1.3 points, 95% confidence interval 0.05 to 2.55). Self reported blinding status did not affect the results. The scores for secondary outcome measures were consistent with the WOMAC A scores.

Conclusion Pain from osteoarthritis of the hip and knee decreases when wearing magnetic bracelets. It is uncertain whether this response is due to specific or non-specific (placebo) effects.

Footnotes

A chart showing flow of participants is on bmj.com
We thank the Mid Devon general practices involved in the study and the research nurses. Mid Devon Primary Care Research Group provided support and advice throughout the study.
Contributors TH had the original idea, led the writing, participated in planning, and was responsible for the overall management of study. CG and AW participated in planning and design, management of study (via steering group), and writing the manuscript. LB implemented the randomisation procedure and contributed to planning and design and writing the manuscript. AH took part in planning and design, analysis and interpretation, and writing the manuscript. EE participated in planning and design, management of study (via steering group), and writing. Mike Dixon took part in planning, design, and recruitment, and commented on the manuscript. Judith Mathie and Chris Rushton participated in management of study (via steering group), data collection, and coordination of trial nurses. Mark Taylor suggested the use of weak bracelets. All authors approved the final manuscript. EE is guarantor.
Funding Arthritis Research Campaign.
Competing interests None declared.
Ethical approval North and East Devon local research ethics committee and West Somerset local ethics research committee.