Limited predictive utility of spinal cord stimulation trial pain metrics for post-implant outcomes
Authors' conclusion
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.
Study context
- Population
- Patients who underwent spinal cord stimulation (SCS) trial and implantation between 2015 and 2022 with ≥6 months follow-up
- Participants
- 124 patients
- Exposure
- Predictive value of SCS trial pain metrics for post-implant pain relief
- Outcome
- Predictive value of trial pain outcomes (NRS, PR-PPR, C-PPR) for post-implantation pain relief
- Follow-up
- 1-6, 6-15, 15-24 and 24-36 months post-implantation
Methodological detailsunivariable linear and logistic regression, Bland-Altman analysis, interaction modeling
- Univariable linear and logistic regression
- Bland-Altman analysis
- Interaction modeling
Main finding
As reported in the abstract
Pain reduction following trial
4.7
∆NRS; 95% CI 4.3 to 5.2
∆NRS strongest predictive value, peak R² at 15-24 months; overall explanatory power modest
0.32
Post-trial NRS strongest predictor of ≥50% long-term pain relief in adjusted models (OR; p=0.002)
0.70
Observational data: associations, not effects.
Further findings
Agreement between patient-reported percent pain relief (PR-PPR) and calculated percent pain relief (C-PPR) (Bland-Altman)
- Mean difference, percentage points (95% limits of agreement −36% to +56%)
- 10
- Poor overall agreement (concordance correlation coefficient (CCC))
- 0.36
Greater than 50% PR-PPR maintained
- At 1-6 months
- 81.5%
- At 24-36 months
- 70.2%
- No significant differences between high and moderate trial responders
Effect modification by baseline covariates
- No consistent patient-specific modifiers identified
Original publication
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