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Effect of Magnetic vs Sham-Magnetic Insoles on Nonspecific Foot Pain in the Workplace: A Randomized, Double-Blind, Placebo-Controlled Trial

      OBJECTIVE

      To determine whether magnetic insoles are effective for relieving nonspecific subjective foot pain in the workplace, resulting in improved job satisfaction.

      SUBJECTS AND METHODS

      A prospective, randomized, double-blind, placebo-controlled study of health care employees who experienced nonspecific foot pain for at least 30 days, which occurred more days than not, was conducted between February 2001 and January 2002 at the Mayo Clinic in Rochester, Minn. Participants were asked to wear either magnetic or sham-magnetic cushioned insoles for at least 4 hours daily, 4 days per week for 8 weeks. The primary outcome variable was reported foot pain (by categorical response of change from baseline and by visual analog scale) at 4 and 8 weeks. Secondary outcome variables included graded intensity of pain experienced during various daily activities and the effect of insoles on job performance and enjoyment.

      RESULTS

      Among 89 enrolled participants, 6 either withdrew before wearing insoles or were noncompliant with follow-up questionnaires; 83 participants remained for full statistical analysis. Participants in both treatment groups reported improvements in foot pain during the study period. No significant differences in categorical response to pain or pain intensity were seen with use of magnetic vs sham-magnetic insoles.

      CONCLUSIONS

      The magnetic insoles used in this study by a heterogeneous population with chronic nonspecific foot pain were not clinically effective. Findings confirmed that nonspecific foot pain significantly interferes with some employees' ability to enjoy their jobs and that treatment of that pain improves job satisfaction.
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      Linked Article

      • What Is Controlled for in Placebo-Controlled Trials?
        Mayo Clinic ProceedingsVol. 80Issue 9
        • In Brief
          Randomized, double-blind, placebo-controlled clinical trials are the gold standard for determining the efficacy of an intervention. Many treatments have shown tremendous promise based on case studies and uncontrolled clinical studies, only to be found ineffective in the context of a carefully conducted placebo-controlled trial. The importance of a credible placebo condition is particularly evident when evaluating the effectiveness of pain treatment, for reasons that we will discuss in detail.
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