Real-World Evidence for the Widespread Effects of Fixed-Site High- Frequency Transcutaneous Electrical Nerve Stimulation in Chronic Pain

Purpose: Transcutaneous electrical nerve stimulation (TENS) produces pain relief by decreasing central excitability and increasing central inhibition. Fixed-site high-frequency TENS (FS-TENS) is a form of TENS in which the device is designed to stimulate a predetermined area rather than to overlap the patient’s pain. The objective of this study was to confirm that FS-TENS has widespread effects beyond the stimulation site in a real-world chronic pain population. Methods: A retrospective cohort study was conducted on users of a FS-TENS device. This device is placed on the upper calf. Study participants were stratified into two groups, those whose pain distribution did not include foot or leg pain (proximal pain group) and those whose pain distribution included foot or leg pain (distal pain group). The outcome measures were changes in pain intensity and pain interference with sleep, activity and mood from a baseline assessment to a 60-day follow-up. FS-TENS dose was characterized by utilization, which was defined as the percentage of days with at least 30 minutes of stimulation. Predictors of pain outcomes were examined by moderated multivariable regression. Results: 1676 FS-TENS users met the inclusion and exclusion criteria. There were 296 (17.7%) participants in the proximal pain group and 1380 (82.3%) participants in the distal pain group. There were no differences in FS-TENS usage between the groups. There were no differences between the two groups for any pain outcome. Age, baseline pain measures, number of painful health conditions, constant pain, weather sensitivity and utilization were predictive of pain outcomes. Distal pain moderated the associations between utilization and sleep/activity interference. The doseresponse associations between FS-TENS utilization and pain outcomes were comparable in participants with distal and proximal pain. Conclusion: These results are consistent with FS-TENS having widespread effects beyond the site of stimulation in real-world chronic pain.