Authors: Hussain N et al.
Journal: Anesthesiology, December 1, 2025. DOI: 10.1097/ALN.0000000000005876
Summary
This systematic review evaluated the statistical robustness of randomized controlled trials assessing spinal cord stimulation (SCS for chronic pain using the fragility index (FI). While SCS has gained wide adoption based on statistically significant trial outcomes, the fragility index provides a complementary lens by quantifying how many outcome-event changes would be required to overturn statistical significance.
The authors identified 30 randomized controlled trials evaluating SCS for various chronic pain indications. The fragility index was calculated for prespecified primary pain outcomes and explored across multiple dimensions, including outcome type, pain indication, conflict of interest, and type of comparator. A higher FI reflects greater trial robustness.
Overall, trials demonstrated moderate to strong statistical stability. The median fragility index across primary outcomes was approximately five, indicating that several outcome events would need to change for results to lose significance. Fragility did not differ meaningfully between dichotomous versus continuous outcomes, primary versus secondary pain outcomes, or trials with versus without reported conflicts of interest.
When stratified by pain indication, trials for persistent spinal pain syndrome type 2, painful diabetic neuropathy, complex regional pain syndrome, and mixed chronic pain etiologies generally demonstrated fragility indices exceeding three, suggesting reasonable statistical robustness across commonly treated SCS populations.
The findings support that most randomized trials underlying SCS pain indications are statistically stable, while also highlighting the value of fragility index reporting as a tool to better contextualize statistical significance beyond p-values alone.
Key Points
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The median fragility index of SCS randomized trials suggests moderate-to-high statistical robustness.
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Fragility was similar across outcome types, pain endpoints, and presence or absence of conflicts of interest.
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Common SCS indications demonstrated fragility indices consistent with stable trial conclusions.
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Fragility index complements traditional statistical reporting by contextualizing trial reliability.
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Routine reporting of fragility may enhance evidence interpretation for chronic pain interventions.
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