THU0489 REAL-WORD EFFECTIVENESS OF FIXED-SITE HIGH-FREQUENCY TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION IN CHRONIC LOW BACK PAIN
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. A small wearable device for localized application while active and sleeping facilitates adequate dosing. <h3>Objectives:</h3> To evaluate the effectiveness of regular FS-TENS use in a large, real-world chronic low back pain (CLBP) population. <h3>Methods:</h3> This retrospective, observational study evaluated use of FS-TENS (worn on upper calf; providing semi-continuous stimulation of sensory nerves) to treat CLBP across a 10-week period using previously collected therapy utilization, demographic, and clinical (pain characteristics/ratings) data. Data collected by the device and companion smartphone app are stored in a cloud database. Device users were eligible for inclusion if they consented to allow their anonymized data to be used for research, had demographic data and pain characteristics indicative of CLBP (daily/weekly pain for &gt;3 months, low back pain, and self-reported herniated disc, spinal stenosis, and/or previous back injury) and had baseline and 10-week pain ratings. Participants were assigned retrospectively to the treatment group or reference group based on device use (% of days with ≥30 min of FS-TENS use) of ≥50% or &lt;50%, respectively. The primary study outcome was the baseline to 10-week change in composite pain, defined as the average of pain intensity and pain interference with activity, sleep, and mood, measured on an 11-point numeric rating scale. Treatment effect was estimated by comparing outcomes in the treatment group to a matched reference group constructed from the original reference group by propensity score (PS) matching estimated by logistic regression. Differences between groups were tested by Wilcoxon rank-sum test for continuous variables and by Pearson chi-square test for proportions. <h3>Results:</h3> A total of 834 device users met the inclusion criteria and were assigned to the treatment (671, 80%) or reference (163, 20%) groups. With few exceptions, the two groups had similar demographic and pain characteristics at baseline: the treatment group was older (58±13 vs 56±14, <i>P</i>=0.035), had lower body mass index (30.5±6.8 vs 31.9±7.9 kg/m<sup>2</sup>, <i>P</i>=0.043), was more likely to have hip pain (<i>P</i>=0.037), and less likely to have diabetes (<i>P</i>=0.002) or prior neck injury (<i>P</i>=0.006). There was no difference in baseline composite pain (6.3±2.1, treatment; 6.5±1.9, reference; <i>P</i>=0.364). Device usage was significantly different between groups (86±15%, treatment; 31±13%, reference; <i>P</i>&lt;0.001), as was duration of therapy per week (46±22 hrs/week, treatment; 11±7 hrs/week, reference; <i>P</i>&lt;0.001), median stimulation intensity (ratio of stimulation to sensation level expressed in decibels) (5.3 dB, treatment; 6.0 dB, reference; <i>P</i>=0.045). Of the 163 participants in the original reference group, 143 (88%) served as matches for the treatment group. The baseline to 10-week follow-up change in composite pain was −0.89±2.30 for the treatment group and −0.01±2.3 for the matched reference group, with a standardized mean difference between the groups of 0.38 (95% confidence interval, 0.27–0.49; <i>P</i>&lt;0.001). <h3>Conclusion:</h3> This study demonstrated that 10 weeks of regular FS-TENS use improved pain outcomes in a real-world sample of CLBP patients compared with a reference group with low FS-TENS use. This study suggests that regular FS-TENS use may be effective in improving pain outcomes in CLBP patients. <h3><b>Disclosure of Interests:</b>&nbsp;:</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.&nbsp;