The use of electromagnetic transduction therapy in patients with chronic myofascial pain: A pilot double-blinded randomised controlled trial

Electromagnetic transduction therapy (EMTT) is a non-invasive magnetic therapy with high oscillating electromagnetic field power. This pilot randomised controlled trial (ChiCTR1900021031) evaluated EMTT's potential efficacy in relieving pain and other non-symptomatic aspects of chronic myofascial pain (CMP). Forty patients with moderate-to-severe CMP were randomised into treatment (real-EMTT) or control (sham-EMTT) group, and received eight sessions of 20-minute real or sham EMTT over four weeks. Generalised estimating equation was used to estimate changes in outcomes, including Numerical Rating Scale (NRS), Brief Pain Inventory Interference Scale (BPI-IS), Beck Depression Inventory (BDI), and Patient Global Impression of Change scale (PGIC) before and up to 6 months after treatment. Recruitment and compliance rates (95% confidence interval) were 39.6% (30.0%-49.8%) and 87.5% (73.2%-95.8%), respectively. There were no significant changes in NRS, BPI-IS and BDI over time (group*time <i>p</i> = 0.929, <i>p</i> = 0.949 and <i>p</i> = 0.608, respectively), and PGIC also did not differ between groups over time (all <i>p</i> > 0.050). Based on the variability of the NRS and non-compliance rate of the patients included in this pilot trial, a total sample size of 148 is required to achieve 80% power if a clinically meaningful reduction in NRS after EMTT treatment is 1.0 (with a superiority margin of 0.3).