936 - Factors Affecting Outcomes in Patients Receiving High Frequency Spinal Cord Stimulators: A Retrospective Study

Objectives: Spinal cord stimulation is an invasive neuromodulation technique used to treat chronic pain by stimulating nerve fibers in the spinal cord and inhibiting pain signal conduction to the brain based on the gate control theory. Trial success and candidacy for permanent implantation is defined as at least 50% pain relief with the trial. Currently, the HF10kHz system from Nevro is the only high frequency stimulator on the market and multiple studies have demonstrated efficacy.

Design: The study aimed to answer which co-morbidities and factors may predict outcomes in patients who receive Nevro 10kHz Spinal Cord Stimulators, comparing patients who were responders at 6 months follow up ( >50% relief), and patients were non-responders (< 50% relief). Eighty-two patients who received Nevro SC stimulators were chart reviewed.

Results: In patients with at least 50% relief of pain relief with trial, there was a statistically significant but inverse relationship between trial response and relief at 6 months, with no relationship found when reported relief of 90% and higher with trial were withheld from the data. There was a statistically significant and inverse relationship between age and improvement with a spinal cord stimulator. In power analysis, a total of 89 subjects were needed to detect a change in R2 of 0.1 attributed to 4 independent variables using an F test with a Type I error of 0.05.

Conclusions: Possible explanations for the study’s results include exaggeration of benefit from trial in the non-responder group, the multifactorial nature of chronic pain with improvements in radiculopathy without improvement in other pain sources, and the subjective and imperfect nature of the visual analog scale. Directions for future studies could consider functional outcomes, which were not available in this retrospective study. It is possible that the quality of communication between the spinal cord stimulator representative and the subject affects outcomes.