Poster Number-5 - 18 Month Outcomes from Multicenter RCT: Spinal Cord Stimulation at 10kHz for Non-Surgical Refractory Back Pain

18 Month Outcomes from Multicenter RCT: Spinal Cord Stimulation at 10kHz for Non-Surgical Refractory Back Pain

Purpose:

Patients with moderate to severe chronic back pain even after exhausting nonsurgical therapies (such as medications, physical therapy, nerve blocks and RFA) are left with very few options if surgical assessment indicates they are not candidates for surgery. If these patients have not had previous spine surgery, they have often been refused authorization for spinal cord stimulation (SCS) by medical payers because of the limited clinical evidence for SCS in this patient population¹. Eighteen-month results are reported here from a randomized clinical trial that was designed to provide the evidence of clinical and cost effectiveness of 10KHz SCS to treat non-surgical refractory back pain (NSRBP).

Methods:

NSRBP patients were enrolled if ineligible for surgery based on surgical consultation.² Subjects were randomized 1:1 to either 10kHz SCS plus conventional medical management (CMM) or CMM alone. Subjects randomized to 10kHz SCS underwent permanent implantation if ≥50% pain relief was achieved during a temporary trial.  Both groups received CMM per standard of care. Appropriate interventional procedures were tried prior to enrollment and continued if provided benefit, as needed. Both groups had the option of crossing over at 6 months if satisfactory pain relief was not achieved.  In addition, all subjects had the option of consenting to a study extension to 24-months.  We present pain relief reported on the visual analog scale (VAS), Oswestry Disability Index (ODI), and quality-of-life (EQ-5D-5L) at 18 months for all implanted patients (original 10kHz SCS arm and the crossover group). Last Observation Carried Forward imputation is used for missing values in the case of withdrawal, missed visits, and not consenting to study extension.

Results: There were 159 patients randomized to either CMM alone (n=75) or to 10kHz SCS in addition to CMM (n=83), with similar baseline characteristics. All primary and secondary study endpoints were met at 3 and 6 months (p< 0.001) comparing CMM to 10kHz group in terms of pain relief, disability, quality of life, and opioid reduction.³  At 6 months none of the 69 implanted patients in the 10kHz SCS arm chose to crossover to CMM arm, while 74.7% (56/75) in the CMM arm crossed over, resulting in 125 total implanted patients. The reported pain relief was stable in all implanted patients at 6, 12, and 18 months with an average VAS of 2.2±2.2 cm, 2.2±2.1 cm, and 2.1±2.1 cm, respectively, compared to a mean baseline of 7.4±1.1 cm (p < 0.001 for all comparisons to baseline). The average reduction in ODI score was 20.6±15.3, 20.7±15.9, and 22.5±17.0 for 6, 12, and 18 months, respectively, approximately 2X the minimum clinically important difference (MCID) of 10 pts.⁴ At 18 months 74% of patients reported clinically significant disability improvement on the ODI with 40% moving from severe/moderate disability to minimal disability. The significant improvement in quality of life was also stable to 18 months with an average utility index increase of 0.185±0.149 at 18 months, more than 2X the MCID.⁵  A total of 5/125 (4%) explants occurred during 18-month follow-up, two due to dissatisfaction with therapy and three to infection (two of which were replaced). 

Conclusion: This large, multicenter study demonstrates that the addition of 10kHz SCS to CMM results in profound and durable improvements in pain relief, function, and quality of life in these NSRBP patients who have been deemed not surgical candidates and exhausted all available appropriate nonoperative medical management.

References: 1. Eckermann JM, Pilitsis JG, Vannaboutathong C, Wagner BJ, Province-Azalde R, Bendel MA. Systematic Literature Review of Spinal Cord Stimulation in Patients With Chronic Back Pain Without Prior Spine Surgery. Neuromodulation. Aug 18 2021.
2. Patel N, Calodney A, Kapural L, Province-Azalde R, Lad SP, Pilitsis J, Wu C, Cherry T, Subbaroyan J, Gliner B, Caraway D. High-Frequency Spinal Cord Stimulation at 10 kHz for the Treatment of Nonsurgical Refractory Back Pain: Design of a Pragmatic, Multicenter, Randomized Controlled Trial. Pain Practice: the official journal of World Institute of Pain 2021;21(2): 171-83.
3. Kapural L, Jameson J, Johnson C, et al. Treatment of nonsurgical refractory back pain with high-frequency spinal cord stimulation at 10 kHz: 12-month results of a pragmatic, multicenter, randomized controlled trial. J Neurosurg Spine.
4. Hagg O, Fritzell P, Nordwall A, Swedish Lumbar Spine Study G. The clinical importance of changes in outcome scores after treatment for chronic low back pain. Eur Spine J. Feb 2003;12(1):12-20.
5. McClure NS, Sayah FA, Xie F, Luo N, Johnson JA. Instrument-Defined Estimates of the Minimally Important Difference for EQ-5D-5L Index Scores. Value Health. Apr 2017;20(4):644-650.