Spinal cord stimulation plus conventional medical management versus conventional medical management alone for severe, non-surgical, refractory back pain: a randomized clinical trial followed by crossover.

Introduction: Chronic low back pain is a major contributor to long-term disability. Many patients lack a clearly identifiable source for their pain on physical examination or imaging or present with multiple pain generators. This subset of patients, who do not have surgical pathology, relies on conservative medical management (CMM) in the absence of effective and lasting treatment alternatives. For those who fail to respond to CMM, spinal cord stimulation (SCS) should be considered as an effective adjunctive therapy for improving pain, disability and health-related quality of life.

Methods: SOLIS is a prospective, multicenter trial that randomized patients with non-surgical, refractory back pain (with or without leg pain) to receive either SCS combined with CMM or CMM alone. The primary endpoint at 3 months compared the proportion of patients with ≥50% overall pain relief without an increase in mean daily opioid use between the SCS+CMM and CMM groups. Three months after treatment activation, patients initially randomized to receive CMM alone had the option to cross over and add SCS to their pain management regimen. Patients in both randomized groups underwent 12-month follow-up visits to assess long-term effects on pain relief, disability, health-related quality of life, global impression of change, and treatment satisfaction.

Results: 147 patients were randomized to SCS+CMM (n=79) or CMM alone (n=68). At the 3-month follow-up, 89.5% of patients who received SCS+CMM (including subperception and paresthesia-based programming modalities) and 8.1% who received CMM alone were classified as study responders (≥50% pain relief without an increase in mean daily opioid use; modified intention-to-treat analysis, p<0.0001). The level of disability due to low back pain improved significantly: the Oswestry Disability Index score decreased by -27.5±15.9 points in the SCS+CMM group versus -7.2±9.9 points in the CMM alone group (p<0.0001). Health-related quality of life also improved at 3 months: the EuroQol 5 Dimension 5 Level questionnaire index score increased by 0.247±0.164 points in the SCS+CMM group versus 0.031±0.151 points in the CMM alone group (p<0.0001). The benefits of SCS were sustained until the 12-month visit. Seven patients experienced serious adverse events related to SCS, including 5 (3.6%) implant site infections resulting in explant.

Conclusion: SCS relieved pain and resulted in clinically significant improvements in functional disability and health-related quality of life in patients with non-surgical, refractory back pain with or without accompanying leg pain.

Trial registration number: NCT04676022.