Limited predictive utility of spinal cord stimulation trial pain metrics for post-implant outcomes.

Authors

Alexander David Keith, Jason S Kilgore, David Anthony Provenzano

Published in

Regional anesthesia and pain medicine. Aug 10, 2026. Epub Aug 10, 2026.

Abstract

This study evaluated the predictive value of pain outcomes reported during spinal cord stimulation (SCS) trialing for short-term, intermediate-term, and long-term post-implantation pain relief, and whether baseline patient characteristics modify these relationships.
A retrospective review identified 124 patients who underwent SCS trial and implantation between 2015 and 2022 with a minimum of 6-months follow-up. Pain outcomes included numeric rating scale pain score (NRS), patient-reported percent pain relief (PR-PPR), and calculated percent pain relief (C-PPR) post-trial and at short-term (ST) 1-6 months (>1 to ≤6 months), intermediate term (IT) 6-15 months (>6 to ≤15 months), long-term (LT) 15-24 months (>15 to ≤24 months), and extended long-term (ELT) 24-36 months (>24 to ≤36 months) post-implantation. Univariable linear and logistic regression assessed predictive value, while Bland-Altman analysis and Lin's concordance correlation coefficient (CCC) evaluated agreement between PR-PPR and C-PPR. Interaction modeling assessed effect modification of baseline covariates.
Patients experienced significant pain reduction following trial (∆NRS 4.7; 95% CI 4.3 to 5.2), with sustained, but attenuating, benefit through 36 months. ∆NRS demonstrated the strongest predictive value (peak R²=0.32 at 15-24 months), though overall explanatory power was modest. In adjusted models, post-trial NRS was the strongest predictor of achieving ≥50% long-term pain relief (OR 0.70, p=0.002). Bland-Altman analysis showed a mean difference of 10 percentage points between PR-PPR and C-PPR (95% limits of agreement -36% to +56%) with poor overall agreement (CCC=0.36). Greater than 50% PR-PPR was maintained in 81.5% at 1-6 months and 70.2% at 24-36 months, with no significant differences between high and moderate trial responders. Covariate interaction modeling did not identify any consistent patient-specific modifiers.
Trial-phase pain metrics demonstrated limited utility in explaining short, intermediate, and long-term pain relief. NRS-based measures showed the most consistent predictive value, while disagreement between PR-PPR and C-PPR raises concerns regarding the reproducibility of percentage-based metrics. These findings emphasize the need for refinement of reliable SCS trial predictors for post-implant pain relief outcomes.

PMID:
42575561
Bibliographic data and abstract were imported from PubMed on 11 Aug 2026.

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