Static magnetic fields for treatment of fibromyalgia: a randomized controlled trial.

OBJECTIVE: To test effectiveness of static magnetic fields of two different configurations, produced by magnetic sleep pads, as adjunctive therapies in decreasing patient pain perception and improving functional status in individuals with fibromyalgia. DESIGN: Randomized, placebo-controlled, 6-month trial conducted from November 1997 through December 1998. SETTING AND SUBJECTS: Adults who met the 1990 American College of Rheumatology criteria for fibromyalgia were recruited through clinical referral and media announcements and evaluated at a university-based clinic. INTERVENTIONS: Subjects in Functional Pad A group used a pad for 6 months that provided whole-body exposure to a low, uniform static magnetic field of negative polarity. Subjects in the Functional Pad B group used a pad for 6 months that exposed them to a low static magnetic field that varied spatially and in polarity. Subjects in two Sham groups used pads that were identical in appearance and texture to the functional pads but contained inactive magnets; these groups were combined for analysis. Subjects in the Usual Care group continued with their established treatment regimens. OUTCOME MEASURES: Primary outcomes were the change scores at 6 months in the following measures: functional status (Fibromyalgia Impact Questionnaire), pain intensity ratings, tender point count, and a tender point pain intensity score. RESULTS: There was a significant difference among groups in pain intensity ratings (p = 0.03), with Functional Pad A group showing the greatest reduction from baseline at 6 months. All four groups showed a decline in number of tender points, but differences among the groups were not significant (p = 0.72). The functional pad groups showed the largest decline in total tender point pain intensity, but overall differences were not significant (p = 0.25). Improvement in functional status was greatest in the functional pad groups, but differences among groups were not significant (p = 0.23). CONCLUSIONS: Although the functional pad groups showed improvements in functional status, pain intensity level, tender point count, and tender point intensity after 6 months of treatment, with the exception of pain intensity level these improvements did not differ significantly from changes in the Sham group or in the Usual Care group.

Responsiveness of fibromyalgia clinical trial outcome measures.

OBJECTIVE: To assess the responsiveness of the Fibromyalgia Impact Questionnaire (FIQ), patient ratings of pain intensity, number of tender points, and total tender point pain intensity score to perceived changes in clinical status in patients with fibromyalgia (FM). METHODS: Using data from a randomized placebo controlled study evaluating efficacy of magnetic therapy in patients with FM, the ability of primary outcomes to detect clinically meaningful changes over a 6 month period was assessed by: (1) degree of association between outcome change scores and patient global ratings of symptom change (Spearman rank-order correlations); (2) ability of these scores to discriminate among groups of patients whose perceived health status had changed to varying degrees (ANOVA); (3) ability of these scores, individually and jointly, to discriminate between patients who had reported improvement and those who did not (logistic regression); (4) effect size, standardized response mean, and Guyatt's statistic were calculated to quantify responsiveness. RESULTS: Correlations showed the outcome measures were moderately responsive to perceived symptomatic change. For FIQ, pain intensity ratings and number of tender points, differences in change scores between globally improved and unchanged groups and between globally improved and worsened groups were significant; for total tender point pain intensity, the globally improved differed from worsened group. FIQ outperformed the other measures in discriminating between patients who reported improvement from those who did not. Summary statistics were consistent with discriminatory analyses, indicating the measures were sensitive to improvement, but relatively unresponsive to decline. CONCLUSION: The FIQ was the most responsive measure to perceived clinical improvement and we recommend its inclusion as a primary endpoint in FM clinical trials.