Authors: Hussain N et al.
Anesthesiology, December 2025. DOI: 10.1097/ALN.0000000000005876
Summary
Spinal cord stimulation (SCS) is increasingly used for refractory chronic pain, but the statistical strength of supporting randomized controlled trials (RCTs) has not been well evaluated. This study systematically reviewed 30 RCTs and assessed their fragility index (FI)—the number of events that would need to change for the primary outcome to lose statistical significance. A higher FI suggests more stable, more trustworthy conclusions.
Across all trials, the median FI for primary pain outcomes was 5.45 (IQR 3.00–11.45), indicating that most RCT conclusions are reasonably robust. The fragility did not differ meaningfully between dichotomous and continuous outcomes, primary versus secondary pain outcomes, or trials with vs. without conflict of interest. Several clinical indications demonstrated particularly strong robustness, including complex regional pain syndrome, painful diabetic neuropathy, persistent spinal pain syndrome type 2, mixed etiologies, and other chronic pain causes.
Overall, the analysis suggests that most SCS RCTs evaluating pain outcomes are statistically stable and that incorporating FI reporting in future trials can help clinicians better interpret the reliability of results when considering SCS for chronic pain.
Key Points
• The median fragility index across RCTs evaluating SCS was moderately high (5.45), suggesting robust findings.
• Trial robustness was similar regardless of outcome type, primary vs. secondary outcome designation, or conflict of interest.
• Highest fragility scores—and thus strongest statistical stability—were seen in trials for CRPS, diabetic neuropathy, persistent spinal pain syndrome type 2, and mixed etiologies.
• Reporting fragility index helps contextualize RCT results and strengthens clinical decision-making about SCS therapy.
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