Two configurations of static magnetic fields for treating rheumatoid arthritis of the knee: a double-blind clinical trial

Objective: To assess the efficacy of a nonpharmacologic, noninvasive static magnetic device as adjunctive therapy for knee pain in patients with rheumatoid arthritis (RA).

Design: Randomized, double-blind, controlled, multisite clinical trial.

Setting: An American and a Japanese academic medical center as well as 4 community rheumatology and orthopedics practices.

Patients: Cohort of 64 patients over age 18 years with rheumatoid arthritis and persistent knee pain, rated greater than 40/100mm, despite appropriate use of medications.

Intervention: Four blinded MagnaBloc (with 4 steep field gradients) or control devices (with 1 steep field gradient) were taped to a knee of each subject for 1 week.

Main outcome measures: The American College of Rheumatology recommended core set of disease activity measures for RA clinical trials and subjects' assessment of treatment outcome.

Results: Subjects randomly assigned to the MagnaBloc (n = 38) and control treatment groups (n = 26) reported baseline pain levels of 63/100mm and 61/100mm, respectively. A greater reduction in reported pain in the MagnaBloc group was sustained through the 1-week follow-up (40.4% vs 25.9%) and corroborated by twice daily pain diary results (p < .0001 for each vs baseline). However, comparison between the 2 groups demonstrated a statistically insignificant difference (p < .23). Subjects in the MagnaBloc group reported an average decrease in their global assessment of disease activity of 33% over 1 week, as compared with a 2% decline in the control group (p < .01). After 1 week, 68% of the MagnaBloc treatment group reported feeling better or much better, compared with 27% of the control group, and 29% and 65%, respectively, reported feeling the same as before treatment (p < .01).

Conclusions: Both devices demonstrated statistically significant pain reduction in comparison to baseline, with concordance across multiple indices. However, a significant difference was not observed between the 2 treatment groups (p < .23). In future studies, the MagnaBloc treatment should be compared with a nonmagnetic placebo treatment to characterize further its therapeutic potential for treating RA. This study did elucidate methods for conducting clinical trials with magnetic devices.