Randomized Clinical Trials on Neurostimulation for Chronic Pain: Do They Comply With the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) Criteria?

BACKGROUND

Variability in outcome reporting among randomized clinical trials (RCTs) evaluating neurostimulation for chronic pain may hinder evidence synthesis and patient-centered care. This study aimed to assess the extent to which RCTs of implantable neurostimulation interventions adhere to the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommendations, which define six core outcome domains for chronic pain research.

MATERIALS AND

METHODS

We conducted a systematic review of 63 RCTs evaluating spinal cord stimulation, dorsal root ganglion stimulation, and peripheral nerve stimulation for chronic pain. We extracted data on whether each of the six IMMPACT-recommended outcome domains-pain intensity, physical functioning, emotional functioning, participant ratings of global improvement or satisfaction, adverse events, and participant disposition-was reported. We also recorded study design, funding source, journal impact factor, device type, and year of publication. A linear regression model assessed associations between IMMPACT adherence and select study characteristics.

RESULTS

All 63 RCTs (100%) reported pain intensity. Reporting of other IMMPACT domains varied: physical functioning (66.7%, n = 42), emotional functioning (57.1%, n = 36), and global impression or satisfaction (66.7%, n = 42). Only 11.1% (n = 7) of studies explicitly referenced the IMMPACT framework, and among these, only three (42.8%) reported all six core domains. Cross-over-designed RCTs reported significantly fewer IMMPACT domains than parallel-group RCTs (β = -1.11, 95% CI -1.76 to -0.47; p = 0.001). No significant associations were found between IMMPACT adherence and journal impact factor, funding source, device type, or publication year.

CONCLUSIONS

These findings highlight ongoing inconsistencies in multidimensional outcome reporting within neuromodulation research. Greater adherence to standardized frameworks such as IMMPACT recommendations is needed to better capture the full spectrum of patient-relevant outcomes, improve trial comparability and external validity, and support broader evidence synthesis. Integration of IMMPACT alongside Consolidated Standards of Reporting Trials may strengthen the quality and relevance of neuromodulation RCTs and promote comprehensive assessments of treatment success.