Presented at the 2012 AAPM Annual Meeting « Back

Novel Clinical Trial Design to Study the Benefits of a Position-Adaptive Spinal Cord Stimulation Feature

Steven Broste, MS, steven.broste@medtronic.com¹, Mark Sun, PhD¹, Ye Tan, MS¹, Mary Robischon, RN¹, Sally McCarville, MS¹, David Caraway, MD PhD², (1) Medtronic, Inc., Minneapolis, Minnesota, (2) Center for Pain Relief TriState, Huntington, West Virginia

Introduction: A robust study design was needed to demonstrate the safety and efficacy of a neurostimulator with a position-adaptive stimulation feature. Patient benefits of this new feature could include added convenience and potentially improved pain relief. Because improvements in one domain should not occur at the expense of the other, a dual-primary objective was developed. Materials and Methods: No minimum pain score or demonstrated need for stimulation adjustment during position change was required for enrollment in the IRB-approved RestoreSensor study, assuring study generalizability. Because the position-adaptive stimulation feature (AdaptiveStim™, Medtronic, Inc., Minneapolis, MN) could be enabled or disabled by clinicians, patients could serve as their own controls. Patients in the 12-week randomized crossover study could experience each stimulation adjustment paradigm separately for 6 weeks, and compare them (Figure 1). Adverse events could also be compared. Separate 5-point Likert scales were developed to compare pain relief and convenience with the position-adaptive feature. The two scales could be cross-tabulated with the shaded section representing the joint responses predefined as "success" for the primary study outcome. Results: Overall, 64 of 74 patients (86.5%) reported success when using the new feature compared to when using only manual adjustments (Table 1). This statistically exceeded the prestated minimum success threshold of 25% (p<0.001). Results did not differ by randomization sequence. Conclusion: The within-patient crossover design enabled robust comparison of position adaptive stimulation with manual programming for pain relief and convenience, which could not have been accomplished reliably or economically with a parallel group design.

Funding: The RestoreSensor study was supported by Medtronic Neuromodulation.