Sustainability of Pain Reduction from Trial Stimulation to Long-Term Follow-Up in Chronic Pain Patients with Spinal Cord Stimulation: A Retrospective Analysis

Background/Objectives: Before permanent implantation of a Spinal Cord Stimulation (SCS) system for treatment of chronic pain conditions a trial phase is standard, though its utility is increasingly disputed. Comparisons of long-term to trial-phase pain levels are sparse, and whether trial pain scores predict system explantation risk is unclear. We compare long-term and trial-phase pain levels in SCS treatment and investigate association between trial numeric rating scale (NRS) pain score and explantation. Methods: This retrospective, single-centre study analysed patients who underwent SCS implantation with long-term follow-up. Patients were included if baseline and trial NRS diaries were available and trial phase was successful. Missing follow-up NRS values were extracted from patient files, multiple imputation addressing remaining gaps. ROC analysis, log-rank test, logistic regression, and Cox proportional hazards models evaluated association between trial-phase NRS and explantation. Results: 71 patients (49.3% female, mean age 53.1 ± 13.0 SD years) were included. NRS reduction during trial was −3.52 from baseline [95% CI: −2.94, −4.09] (p < 0.0001). NRS reduction from baseline to long-term follow-up was −1.94 [95% CI: −1.1, −2.74] (p < 0.0001). NRS increased by 1.58 [95% CI: 0.78, 2.38] from trial to follow-up (mean follow-up at 4.42 years [95% CI: 3.53, 5.30]) (p < 0.0002). Higher trial NRS was associated with higher odds of explantation. (Odds Ratio: 1.38 per one-point NRS increase (95% CI: 1.01–2.04, p = 0.0458). Conclusions: In SCS there is significant attrition of pain reduction from trial to long-term follow-up. Higher trial NRS showed a possible association with higher odds of explantation. Therefore, pain reduction during trial phase does not necessarily reflect long-term results and utility of trial-phase pain levels for estimation of explantation risk warrants further investigation.