A Pulsed Electromagnetic Field Therapy Device for Non-Specific Low Back Pain: A Pilot Randomized Controlled Trial

Low back pain (LBP) is among the most common health conditions accounting for the greatest individual and societal burden worldwide [1]. Results from the Global Burden of Disease study show that in 2015 over half a billion people worldwide had LBP of > 3-month duration, and LBP and neck pain are the leading causes of years lived with disability in most countries and age groups [2].

It is typically not possible to identify precise anatomic causes to account for the appreciable negative impact LBP has on patients; consequently, most instances of LBP are labeled non-specific LBP [3]. This is widely described as “low back pain not attributable to a recognizable, known specific pathology (e.g., infection, tumour, osteoporosis, fracture, structural deformity, inflammatory disorder, radicular syndrome, or cauda equina syndrome)” [4]. A range of different classes of interventions has been developed and tested in adults with non-specific LBP, and current clinical practice guidelines recommend a number of non-pharmacologic options as first-line therapies [5]. These include heat, massage, acupuncture, spinal manipulation, yoga, exercise, cognitive behavioral therapy, and others. While all of these interventions have demonstrated clinical benefit, none have been shown to consistently provide substantial, long-term reductions in pain with increased function for the majority of LBP sufferers [6, 7]. Pharmacologic therapies are also commonly used, although these have no greater evidence of effectiveness [5]. Particularly concerning is that opioid pain relievers are often used for LBP, despite limited evidence of effectiveness [8] and substantial evidence of risk of serious adverse events including death [9].

Identifying safe and effective non-pharmacologic treatment options for LBP is aligned with the Institute of Medicine’s national priorities for pain management [10]. Pulsed electromagnetic field (PEMF) therapy is one such treatment that is supported by promising results. PEMF therapy has been shown to improve bony fusion after spinal fusion surgery [11, 12] and decrease postoperative pain and swelling after plastic surgery [13]. Recently, investigators have demonstrated improvements in patients with chronic back pain after using PEMF therapy [14, 15]. However, these trials are preliminary and need to be replicated in rigorous fashion. Determining the effectiveness of a portable PEMF device as a treatment for LBP can significantly improve the management of LBP patients.

The purpose of this project is to conduct a randomized controlled pilot study comparing a portable PEMF device with a sham device for participants with mixed-duration non-specific LBP.

In total, 68 individuals were screened and 42 were enrolled in the study (Fig. 1). Subject demographics and baseline characteristics, including symptom duration and mean Oswestry and NRS scores, were similar between study groups (Table 1). Of the 42 enrolled, 25 completed the study and were analyzed. One missing measurement was imputed using the median scores method.

This pilot double-blind, randomized clinical trial presents encouraging results for the use of portable PEMF therapy to improve function and pain in patients with non-specific LBP. Both the active treatment and sham groups were closely aligned with respect to the distribution of acute, subacute, and chronic cases. We found participants receiving usual care plus active PEMF therapy reported greater improvement in LBP at 6 weeks, and LBP-related function at 6 and 12 weeks, compared with those receiving usual care plus sham therapy. Adverse effects were very rare and not serious.

It is interesting that the active group was superior to the sham group regarding the NRS score at week 6 but similar at week 12. Prior work has shown that improvements in LBP intensity scores and function scores are often independent [16] and that functional recovery is a more meaningful outcome [17]. It is possible that differences in compliance with device usage may be related to the duration of pain intensity changes; therefore, future studies on the PEMF device should monitor this closely. While it was beyond the scope of this work to assess differences in responses between subjects with acute pain versus chronic pain, symptom duration may impact both compliance and outcome, particularly in light of the biopsychosocial context of chronic pain.

PEMF therapy has been shown to reduce expression of gene encoding for major proinflammatory cytokine IL-1α and increase expression of major anti-inflammatory IL-10 in mice [18]. Other work demonstrated that PEMF therapy produces an anabolic effect on osteoblasts and chondrocytes [19, 20].

Prior work has shown that patients want to have information on and access to non-pharmacologic treatment options to manage various musculoskeletal pain conditions [21]. Participants in this study continued to receive usual care—which may have included pharmacologic therapies—at their discretion. The fact that we were able to recruit and enroll participants in this trial supports the hypothesis that there is a demand for PEMF therapy even among those non-specific LBP suffers who receive other forms of care. Although we did not control for variation in usual care, we expect that this was similar between groups at baseline and after exposure to PEMF.

This work has several primary limitations. Although the study was a randomized, double-blind, sham-controlled trial, the sample size was relatively small because of attrition among enrolled participants. The most common reasons reported for discontinuing were symptoms not improving or no longer interested in participating. We did not provide incentives to participants to encourage adherence, and future work should consider doing this. Nevertheless, we report results that are statistically and clinically meaningful, and data from this study can be used to inform the design and sample size of future studies. Although we encouraged participants to adhere to the device usage schedule, since the usage was self-directed ultimately we could not control the exact PEMF dosage the subjects received. However, this might be considered a positive from a pragmatic perspective since most home treatments for LBP (devices, topicals, medications) are typically used on an as-needed basis. While usual care received at the UBCC was similar between groups, we did not assess any care received outside of that setting.

This work provides evidence that it is feasible to conduct a randomized controlled trial of the MDCure PEMF device on patients with mixed duration non-specific LBP. The outcomes support the hypothesis that this device can be safe and effective for reducing disability and pain intensity in this population. Further investigation with a larger sample size is warranted. Future studies should also examine the optimal patient profile, the relationship between PEMF therapy and the use of other healthcare services, including analgesic medications, and the impact on healthcare costs.

It is feasible to conduct a clinical trial of a PEMF therapy device for non-specific LBP. This work shows that the device was safe and provides preliminary evidence of effectiveness in improving function in patients with non-specific LBP.