THU0490 PREDICTORS OF CHRONIC PAIN RELIEF BY FIXED-SITE HIGH-FREQUENCY TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION
Authors: Xuan Kong, Dawn Chesher
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Fixed-site high-frequency transcutaneous electrical nerve stimulation (FS-TENS) is a form of TENS in which the stimulator is designed for a predetermined location rather than for co-localization with the patient's pain. Previous studies in individuals with chronic pain have demonstrated the efficacy and real-world effectiveness<sup>1,2</sup> of a small wearable FS-TENS device designed for localized application to a single placement site to ensure comfort while both active and sleeping. Results demonstrated that 50–80% of FS-TENS users with chronic lower extremity or low back pain experience clinically meaningful pain relief,<sup>1,2</sup> and daily use of the device was associated with greater pain relief relative to intermittent use.<sup>2</sup> <h3>Objectives:</h3> To determine predictors of a positive FS-TENS response. <h3>Methods:</h3> This retrospective, observational study evaluated users of a FS-TENS device to treat chronic pain over a 10-week period. The device and companion smartphone app collected dosage data, demographics, pain characteristics, and pain ratings and all data were stored in a cloud database. The primary study outcome was the baseline to week 10 change in composite pain (average of pain intensity and pain interference with sleep, activity, and mood). Device users were included if they provided demographic data, pain characteristics indicative of chronic pain, and baseline and week 10 pain ratings. Participants were defined as a responder or comparator based on their change in composite pain (responder: ≥15% decrease; comparator: ≥15% increase). Stepwise forward probit regression was used to determine independent predictors. <h3>Results:</h3> There were 451 responders and 263 comparators. Independent predictors (Table) that were associated with greater response to FS-TENS included age, baseline composite pain, adherence/utilization rate (defined as the percentage of days with at least 30 minutes of stimulation), and stimulation intensity (defined as the ratio of therapeutic stimulation to sensation threshold, expressed in decibels). Negative predictors (associated with lower response) included history of headache/migraine and diabetes. The area under the receiver operating characteristic curve was 0.76 (95% confidence interval, 0.72–0.79). <h3>Conclusion:</h3> FS-TENS effectiveness is predicted from baseline pain characteristics and dosage variables, such as frequency/regularity of use and stimulation intensity, with moderate accuracy. <h3>Reference:</h3> [1] Gozani SN. J Pain Res. 2016;9:469-79. 2. Kong X, Gozani SN. J Pain Res. 2018;11:703-14. <sup>a</sup>Adherence, percentage of days with at least 30 minutes of stimulation. <sup>b</sup>Stimulation intensity, ratio of therapeutic stimulation to sensation threshold expressed in decibels (20log[therapy/sensation]). All coefficients <i>P</i>&lt;0.05. <h3>Disclosure of Interests:</h3> Xuan Kong Employee of: Xuan Kong is an employee of NeuroMetrix, Inc., Dawn Chesher Employee of: Dawn Chesher is an employee of GlaxoSmithKline Consumer Healthcare.