Novel Once-daily-dose versus Continuous 10khz Stimulation: A Pivotal, Blinded, Multisite Study Demonstrates Equivalent Efficacy

Introduction: Spinal cord stimulation (SCS) has been successfully used to treat chronic intractable pain for over five decades.1 Continuous 10kHz-SCS in particular has shown superiority to low frequency SCS.2 10kHz-SCS works via a unique mechanism, enabling anatomic lead placement and programming directly for pain relief, rather than requiring paresthesia overlap and comfort.2,3,4 It was recently reported that the ‘wash-out’ time of 10kHz-SCS is up to 4x longer than other SCS waveforms.5,6 To take advantage of this long-acting characteristic of 10kHz-SCS, a pivotal multisite IDE study was initiated to demonstrate equivalent clinical efficacy of brief, once-daily 10kHz-SCS (10kHz-QD) compared to continuous 10kHz-SCS delivered over a full 24 hours.

Methods: Investigational Device Exemption was obtained to enable delivery of 10kHz-QD at a once-daily dose of 4-hour (4hr-10kHz-QD), 2-hour (2hr-10kHz-QD), and 30-minute (30min-10kHz-QD). Technical modifications were made to the system so patient’s device charging requirements would not change, so patients remained blinded to stimulation mode being tested and were not biased by reductions in charge duration. Criteria for enrollment was at least 3 months of successful pain relief (≥50%) with continuous 10kHz-SCS. Initially patients were programmed to 2hr-10kHz-QD and evaluated at 3 months, and over the course of the 12-month study, depending on the outcome, 4hr-10kHz-QD or 30min-10kHz-QD was also evaluated as shown in Figure 1. A successful response was maintenance of pain relief, defined as no more than 20 mm increase from baseline in the reported pain on the visual analogue scale after 3 months of 10kHz-QD. The primary and secondary endpoints were met if at least 79% of patients maintained pain relief.

Results: IRB approval was obtained at sixteen study sites where 109 patients were enrolled and 102 were activated with 2hr-10kHz-QD therapy. Study flow and discontinuations are shown in Figure 1. The 2hr-10kHz-QD effectiveness endpoint was met with worst-case scenario for missing data, 99/101 (98%) maintained pain relief (one patient was not included due to mistakenly being programmed to 4hr-10kHz-QD). The 30min-10kHz-QD effectiveness endpoint was also met using multiple imputations for missing data, resulting in an average of 88% of patients maintaining pain relief (Figure 2).

Conclusion: These results provide compelling evidence that because of the unique mechanism of action of 10kHz-SCS, a short daily dose of 10kHz-QD provides long-acting pain relief throughout the day, maintaining therapeutic effect. Additionally, due to the reduced stimulation requirements, the patient experience may be enhanced through decreasing the frequency of and duration of recharging.