Pain Relief and Multidimensional Outcomes of Fast-Acting Subperception Spinal Cord Stimulation Therapy for Chronic Pain: The FAST Prospective, Multicenter Study

IntroductionFast-acting subperception therapy in spinal cord stimulation (FAST-SCS) uses low-frequency, subthreshold stimulation to engage the dorsal column-mediated surround inhibition mechanism and thereby relieve pain. Our study was performed to better characterize the multidimensional long-term clinical outcomes of FAST-SCS therapy in patients with chronic low back and/or leg pain.

MethodsOur prospective, multicenter, single-arm, open-label trial, conducted at 12 pain management centers across the USA, included male and female patients with chronic low back pain with/without leg pain refractory to conservative therapy. All eligible patients received an SCS implant. Outcomes evaluated included pain relief, disability, mobility, health-related quality of life, sleep quality, depression, pain catastrophizing, and global impression of change.

ResultsFifty-six patients received a permanent SCS implant and 55 were activated with FAST-SCS therapy. At 12 months, 89% and 59% of patients achieved ≥ 50% and ≥ 80% pain relief, respectively (p < 0.0001), and pain intensity (verbal numerical rating scale) decreased by 4.9 ± 2.2 points (p < 0.0001). Significant improvements were observed in disability (Oswestry Disability Index - 24 ± 16 points, p < 0.0001) and endurance (6-Minute Walk Test + 73 ± 96 m, p < 0.0001), while mobility and balance improved without reaching statistical significance (Timed Up-and-Go test - 7.5 ± 37.5 s, p = 0.17). All psychosocial measures improved significantly at 12 months compared to baseline, with an increase in the EQ5D-5L index (+ 0.200 ± 0.182, p < 0.0001) and decreases in the Pittsburgh Sleep Quality index (- 3.96 ± 4.31, p < 0.0001), Pain Catastrophizing Score (- 13.3 ± 11.4, p < 0.0001), and Beck Depression Index (- 7.9 ± 10.0, p < 0.0001). At 12 months, 87% of patients reported being "much" or "very much" improved. Responses to FAST-SCS were at or above the minimal clinically important differences across all measured clinical dimensions.

ConclusionThis prospective study demonstrated that FAST-SCS provided statistically significant, multidimensional benefits across pain, disability, mobility, and psychosocial outcomes over 12 months in patients with chronic low back and/or leg pain. These findings support the use of FAST-SCS in this patient population.

Trial registrationClinicalTrials.gov (NCT04618471). https://www. CLINICALTRIALS: gov/study/NCT04618471 .