Self-administered tDCS reduces knee osteoarthritis pain in older adult patients

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Home-based, self-administered transcranial direct current stimulation (tDCS) has demonstrated feasibility, acceptability and significant reductions in clinical pain intensity in older adults with knee osteoarthritis, as per a randomised controlled trial (RCT) published in the journal Brain Stimulation.

The study’s authors, Hyochol Ahn (Florida State University College of Nursing, Tallahassee, USA) and colleagues, note that this approach holds the potential to increase the accessibility of tDCS therapy—but future studies, including multicentre RCTs, are needed to validate their findings.

As the authors note at the outset of their report, arthritis is the leading cause of work disability in the USA, and osteoarthritis is the most frequent form of arthritis, with knee osteoarthritis showing the highest incidence. They also detail that the current standard of care for clinical treatment comprises mainly of prescribed analgesic medications—but this approach has limited efficacy for knee osteoarthritis pain and can lead to significant adverse effects, especially in older adults.

With this in mind, they set out to assess “one of the more promising non-pharmacological interventions” for these patients: non-invasive brain stimulation therapy. Specifically, they built on a recent pilot RCT, carried out in the clinical setting, in which significant pain benefits were obtained without serious adverse effects, by evaluating the feasibility and efficacy of at-home, self-administered tDCS for knee osteoarthritis pain.

Ahn and colleagues conducted a Phase 2, double-blind RCT with two parallel groups (sham and active tDCS). A total of 120 patients aged 50–85 years (mean age=66 years, 68.3% female) were randomly assigned across these two groups. The researchers detail that randomisation balanced the allocation of patients to each arm with respect to distributions of age, race and sex.

Enrolled patients were assigned to receive 15 daily sessions of 2mA tDCS for 20 minutes (n=60) or sham tDCS (n=60) over the course of three weeks, with remote supervision being provided via telehealth. Clinical pain intensity was measured by the Numeric Rating Scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), while data on tDCS experiences were also collected via a questionnaire, the authors note.

Active tDCS significantly reduced pain intensity compared to sham tDCS after completion of the 15 daily sessions in the study. NRS changes from baseline to three weeks were found to be significantly different between the two groups, with an average decrease of 24.07 being observed in the active group compared to just 1.08 in the sham group. In addition, the average NRS decrease from baseline at three months was 14.27 in the active group versus 0.43 in the sham group. However, while WOMAC scores decreased from baseline at both three weeks and three months, these decreases did not represent a statistically significant difference.

Responders in the study were defined as those patients who had at least a 30% reduction in NRS scores from baseline to three weeks. There were 36 responders and 24 non-responders in the active tDCS group, and 14 responders and 46 non-responders in the sham tDCS group. And, according to Ahn and colleagues, home-based tDCS was “well-received” and patients showed high levels of satisfaction with their experience. Overall, they found that the device was easy to use and felt confident using it, and appreciated receiving guidance remotely via videoconference. All participants tolerated tDCS well without experiencing any serious adverse effects, the authors add.

“To our knowledge, this is the first RCT evaluating the efficacy of home-based, self-administered tDCS for patients with osteoarthritis pain,” Ahn and colleagues conclude. “We found that home-based tDCS with real-time remote supervision was associated with significant improvement in clinical pain intensity up to three months after a three-week treatment. These Phase 2 results corroborate our previous preliminary findings on the feasible and acceptable application of a two-week treatment with tDCS in the home setting for older adults with osteoarthritis—and extend these by providing evidence of efficacy in the longer term [three months].”

The authors also outline the wider relevance of their study, citing the fact home-based implementation of tDCS is “very meaningful” for a population with reduced mobility, while reducing the reliance on pharmacological treatment is “a considerable advantage, especially in an older population”.

Despite the limitations of their research, including the potential variability of self-administered tDCS therapy, Ahn and colleagues state that these results offer promise regarding the long-term efficacy of this approach, and “set the stage” for further research involving larger samples and effectiveness assessments. “Future trials need to explore optimal dosage for knee osteoarthritis pain relief on two aspects: the magnitude of the effect, and the duration and maintenance of benefits,” they add.


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