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Introduction to Evidence-Based Practice: Practice Case #2

Learn all about evidence-based practice.

Practice Case 2: Physical therapy and the Magnetic Bracelet

This is a self-correcting exercise. Click on the letter (A, B, or C) or "Quiz Yourself" for a pop-up box with the response.

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ASSESS the patient
Start with the patient -- a clinical problem or question arises from the care of the patient

You are working in an out-patient Physical Therapy Department in a rural community in North Carolina.  Your regular patient, Ms. Baxter is here for her monthly visit for physical therapy related to osteoarthritis of the hip.  She is 65 years old, recently retired and has no other serious medical problems.  She shows up wearing a new magnetic bracelet which her daughter sent her.  Her daughter swears that this will help the hip pain.  Ms. Baxter is very skeptical and asks you if you would recommend the bracelet for pain control.  You don't know if there is any good evidence to demonstrate the effectiveness of the magnetic bracelets but promise to look into it before her next visit.  Will this bracelet help her hip pain?
 
ASK the question

Choose the BEST clinical question:

 Do magnets help control pain in elderly patients?

 Do magnetic bracelets help control pain in patients with osteoarthritis?

Do magnetics help control pain in patients with osteoarthritis of the hip?

 

ACQUIRE the evidence

Choose the best PubMed search strategy to address the clinical question.

Search: magnets AND pain AND elderly     Limited to English

Search: magnetics AND osteoarthritis AND hip      Limited to randomized controlled trial

Search: magnetics AND pain     Limited to randomized controlled trial

 

APPRAISE the evidence

This are a couple of randomized controlled trials found in PubMed for this topic.  This one is Free in PubMed Central: Harlow T. Randomised controlled trial of magnetic bracelets for relieving pain in osteoarthritis of the hip and knee. BMJ. 2004 Dec 18;329(7480):1450-4. PubMed PMID: 15604181; PubMed Central PMCID: PMC535975.

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.

Are the results valid?

You will need to read the full article to address the validity questions. Click on the link above to get a free copy of the article. Evaluating the medical literature is a complex undertaking. You will find that the answers to the questions of validity may not always be clearly stated in the article and that you may have to use your own judgment about the importance and significance of each question.

Randomization: Were patients randomized?

Concealed allocation: Was group allocation concealed?

Baseline characteristics: Were patients in the study groups similar with respect to known prognostic variables?

Blinding: To what extent was the study blinded?

Follow-up: Was follow-up complete?

Intention to Treat: Were patients analyzed in the groups to which they were first allocated?

Equal treatment: Aside from the experimental intervention, were the groups treated equally?

What are the results & how can I apply them to patient care?

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.

The results are reported as a continuous variable (change in scores).  This does not allow for calculations of Absolute and Relative differences or Number-Needed-to-Treat.

Questions to consider before applying the results of a study to your patient:

 

  • Were the study patients similar to my population of interest?
  • Does your patient match the study inclusion criteria? If not, are there compelling reasons why the results should not apply to your patient?
  • Were all clinically important outcomes considered?
  • Are the likely treatment benefits worth the potential harm and costs?

 

APPLY: talk with the patient

Return to the patient -- integrate that evidence from the study with clinical expertise, patient preferences and apply it to practice

Think about your patient, her goals, the evidence you found,  the adverse effects of the magentic bracelet and what you would discuss with her at your next visit.