Passive recharge burst spinal cord stimulation for the treatment of refractory nonsurgical low back pain: 24-month results from a prospective randomized controlled trial and predictors of success

Background: Spinal cord stimulation (SCS) is an established treatment for chronic pain, but long-term results are limited. The objective of this manuscript was to evaluate the 24-month durability of outcomes for patients with nonsurgical refractory chronic low back pain (NS-CLBP) treated with implanted burst SCS, including common diagnoses of NS-CLBP, and predictors of SCS success. Methods: The DISTINCT study was a prospective, multicenter, randomized, controlled trial that investigated the use of SCS for NS-CLBP compared to conventional medical treatment alone. Efficacy and safety data were collected after the optional crossover at 6 months. Univariable and multivariable regression analyses were performed for predictor analyses at 24 months. Dependent variables were pain intensity (NRS), back pain-related disability (ODI), and pain catastrophizing (PCS). Independent variables were selected baseline characteristics, including the PainDetect questionnaire to assess pain as neuropathic (vs. mechanical/nociceptive). Results: NRS responder rates (≥50% reduction) at 24 months for SCS and crossover patients were of 77% and 79%, respectively. Secondary outcomes indicated significant sustained improvements in ODI, PCS, and reduced healthcare utilization. Six serious adverse events were reported and resolved without sequelae. Improvements on the NRS, ODI, and PCS for common subetiologies mirrored those of the overall NS-CLBP group. After adjusting for covariates, higher baseline PCS scores and leg pain were predictors of super-responders, or patients who responded to all 3 scales. Patients with predominantly neuropathic pain reported more robust 24-month ODI and PCS outcomes than patients with mechanical/nociceptive pain. Patients reported similar NRS improvements regardless of pain type. Conclusions: Implanted passive recharge burst SCS provides a significant and sustained therapeutic effect 2 years after implantation in patients with NS-CLBP. Even patients with the highest symptom burden report success at 24 months. Although neuropathic pain increases the magnitude of burst SCS success in NS-CLBP, particularly regarding disability and catastrophizing, patients with nociceptive pain also obtain substantial benefit.