Do Spinal Cord Stimulators Really Help for Chronic Pain?

By Michael Rubin, MD

Professor of Clinical Neurology, Weill Cornell Medical College

SYNOPSIS: A comprehensive analysis of a large clinical database regarding treatment of patients with chronic low back pain did not support the benefit of spinal cord stimulators compared to conventional medical management for chronic pain.

SOURCE: Dhruva SS, Murillo J, Ameli O, et al. Long-term outcomes in use of opioids, nonpharmacologic pain interventions, and total costs of spinal cord stimulators compared with conventional medical therapy for chronic pain. JAMA Neurol 2023;80:18-29.

Introduced in the late 1960s for the treatment of chronic pain, epidural spinal cord stimulation (SCS) of the dorsal columns was first systematically reviewed in 1995 by Turner et al, who suggested SCS might be beneficial for neuropathic pain. Roundly criticized for its inclusion and reliance on observational studies, a subsequent Cochrane Review in 2004 nevertheless supported the original findings, as did a follow-up Turner review using evidence-based medicine criteria to grade available studies. Compared to repeated lumbosacral spine surgery, the sole randomized controlled trial at the time concluded that SCS offered better pain relief, although perhaps not functional improvement. Is SCS better than conventional medical management (CMM)?

Using data from Optum Labs Data Warehouse, spanning Oct. 1, 2015, to Aug. 21, 2020, and comprising medical and pharmacy claims, this retrospective, comparative effectiveness research study reviewed records of patients 18 years of age or older with a diagnosis of failed back surgery syndrome, complex pain syndrome, complex regional pain syndrome, and any other chronic post-surgical back or limb pain condition. To ensure consistent treatment patterns, inclusion criteria required contiguous pharmacy and medical coverage six months prior to, and 12 months post, cohort entry.

Permanent SCS placement patients were compared to those who received CMM only, consisting of pharmacologic pain management, spine surgery, radiofrequency ablation, epidural and facet injections, physical therapy, chiropractic management, and acupuncture. Treatment initiation was set at the date of permanent SCS placement for the SCS group, and CMM patients were randomly given an index date matching the distribution of the SCS group index dates. Exclusionary criteria included patients with malignancy, sacral neuromodulation for incontinence, disabling neurologic deficits, or neurogenic bladder. Primary outcome measures were chronic opioid use and epidural and facet injection use, with secondary outcomes comprising radiofrequency ablations, new spine surgery, and refills for nonsteroidal anti-inflammatory drugs (NSAIDs), systemic corticosteroids, antidepressants, gabapentinoids, or benzodiazepines. The total cost of care, medical and surgical costs, and pharmacy costs also were examined. Statistical analysis included modeling using generalized linear models with a gamma distribution and log link, and generalized linear models with a Poisson distribution, with significance considered to be a two-sided P value < 0.05.

Among the initial 6,202 patients in the SCS group and 215,686 in the CMM group, 1,419 SCS and 91,307 CMM patients satisfied the criteria and composed the final prepropensity score-matched sample, which, using 1:5 matching, resulted in a final study cohort of 1,260 SCS and 6,300 CMM patients. Compared to the CMM group, during the first 12 months after achieving baseline balance, patients treated with SCS filled a higher number of opioid prescriptions and were more likely to have chronic opioid (54.9% vs. 51.8%) and long-acting opioid use (22.5% vs. 18.5%).

During the following 12 months, SCS patients did not appreciate any significant reduction in pharmacologic pain treatment and had similar adjusted odds of chronic opioid and long-acting opioid use. Among patients taking opioids during the six-month baseline period, SCS was not associated with a higher rate of opioid discontinuation. Regarding NSAIDs, muscle relaxants, steroids, antidepressants, gabapentinoids, and benzodiazepines, no significant differences between the groups were found during the first 12 months, but during months 13-24, SCS patients were more likely to fill prescriptions for antidepressants and gabapentinoids, although they were less likely to fill prescriptions for benzodiazepines.

During months 1-12, fewer SCS patients underwent epidural and facet injections, but this was not true for months 13-24. Fewer radiofrequency ablations were performed among the SCS group during the first 12 months compared to the CMM group, but no difference was seen in months 13-24. Emergency department visits and hospitalizations were similar in the two groups during the 24 months of follow-up, but the mean cost per month was $5,531 for SCS vs. $4,008 for CMM patients (P < 0.001). Complications occurred in 17.9% (n = 226) of SCS patients, including infection of the lead or generator or both, or breakdown, displacement, or other mechanical complications.

Compared to CMM, SCS is not associated with less opioid use or fewer nonpharmacologic pain interventions at two years, is more costly, and commonly is associated with complications.

COMMENTARY

Benefit from SCS has been reported to accrue in the subset of patients with chronic back pain, with or without radicular leg pain, who have not undergone prior lumbar spine surgery.¹

A systematic literature search of Medline, PubMed, Embase, and the Cochrane Library disclosed 16 publications comprising 10 primary studies, which demonstrated pain reduction, improved function, improved quality of life scores, reduced opioid usage, acceptable safety profile, and high patient satisfaction following SCS. However, not all studies were statistically significant, and three of the six authors reported receiving funds from Nevro Corporation, a manufacturer of spinal cord stimulators. Benefit from SCS remains uncertain.

REFERENCE

1. Eckermann JM, Pilitsis JG, Vannaboutathong C, et al. Systematic literature review of spinal cord stimulation in patients with chronic back pain without prior spine surgery. Neuromodulation 2021; Aug 18. doi: 10.111/ner.13519. [Online ahead of print].