The use of home-based, self-administered transcranial direct current stimulation (tDCS) was feasible and decreased the intensity of pain in older adults with knee osteoarthritis (OA), according to study findings published in Brain Stimulation.
Researchers conducted a double-blind, randomized, sham-controlled, phase 2, parallel-group study (ClinicalTrials.gov identifier: NCT04016272) to evaluate the efficacy and feasibility of tDSC.
A total of 120 participants (68% women) between the ages of 50 and 85 years (mean age, 66 years) with knee OA pain were randomly assigned in a 1:1 ratio to receive either 15 daily sessions of tDCS with a current intensity of 2 mA for 20 minutes (n=60) or sham tDCS (n=60) during a 3-week period, with remote supervision provided via telehealth. Clinical pain intensity was measured with the Numeric Rating Scale (NRS) and the Western Ontario and the McMaster Universities Osteoarthritis Index (WOMAC). Data on the tDCS experience were obtained via questionnaire.
Changes in clinical pain intensity evaluated with the NRS was the primary outcome measure for data analysis purposes, with the primary endpoint at 3 weeks (ie, at the end of 15 treatment sessions), and the secondary endpoint at 3 months.
Results of the study showed that the use of active tDCS was associated with significantly reduced pain intensity compared with sham tDCS following completion of the 15 daily sessions (P <.0001).
The average decrease in NRS at 3 weeks from baseline was 24.07±21.55 for the active treatment group vs 1.08±16.46 for the sham group. At 3 months from baseline, the average decrease in NRS was 14.27±24.94 in the active treatment group vs 0.43±25.42 in the sham group. Additionally, the WOMAC score decreased by 10.95±14.20 at
3 weeks from baseline in the active treatment arm vs 8.08±10.56 in the sham arm. At 3 months from baseline, the WOMAC score decreased by 8.92±16.35 in the active treatment arm vs 8.67±14.64 in the sham arm. Responders were defined as those participants who had at least a 30% reduction in NRS scores from baseline to 3 weeks, with 36 responders and 24 nonresponders reported in the active tDCS group compared with 14 responders and 46 nonresponders in the sham tDCS group.
High levels of satisfaction with the tDCS experience were observed among the participants, with no adverse events reported.
Limitations of the study included possible variability associated with the use of self-administered tDCS, as it may not have conferred the same accuracy and consistency as did the use of clinic-based, professionally administered sessions. The study also did not measure any biomarkers or evaluate neuronal mechanisms, since it was focused on efficacy.
The study authors concluded that future mechanistic studies on tDCS targeting OA pain that focus on biomarkers or neuronal mechanisms are warranted. These studies should involve larger samples of patients and the evaluation of effectiveness.
Martorella G, Mathis K, Miao H, Wang D, Park L, Ahn H. Self-administered transcranial direct current stimulation for pain in older adults with knee osteoarthritis: a randomized controlled study. Brain Stimul. 2022;15(4):902-909.