Patients with chronic refractory neuropathic pain who had a spinal cord stimulation (SCS) device implanted were found to still experience pain relief 2 years later, according to a study published in the European Journal of Pain.
Although SCS has been successfully used to treat refractory neuropathic pain, few studies have examined the long-term efficacy and safety of this approach. The French Authority for Health commissioned a post-market study to assess real-world clinical implications and the risk/benefit profile of SCS in this patient population.
In this multicenter prospective representative non-controlled non-randomized observational trial (Clinicaltrials.gov identifier NCT01778426), a total of 402 patients with chronic neuropathic pain were enrolled between January 2012 and December 2013 from 28 centers across France to evaluate the Medtronic SCS device. Participants either had undergone a single device implantation (“primo” group; n=264; 56% men; mean age, 49.6; median pain duration, 3.5 years) or had received a replacement device (“replacement” group; n=138; 57% men; mean age, 56.5; median pain duration, 10 years). After 1 and 2 years, 83% and 77% of patients, respectively, completed follow-up.
Study outcomes assessed at baseline and 1 and 2 years post-implantation included evaluation of pain intensity, pain relief, daily functioning, and satisfaction. The primary outcome was the percentage of patients (responder rate) from the primo group who reported a ≥50% reduction in pain between baseline and 2-year follow-up.
After 2 years, the probability of experiencing ≥50% pain relief was 59.4% in the primo group (95% CI, 55-63%;(P <.0001), with response rates of 67%, 36%, and 55% in the upper limbs, back, and lower limbs, respectively. The majority of participants reported improvements in daily activities (82%) and pain relief (89%), with 91% satisfied with the therapeutic outcome and 93% willing to repeat the procedure. In addition, 74% of patients indicated a ≥30% decrease in pain at 2 years. Participants in the replacement group had similar satisfaction levels (86% to 98%) with the SCS treatment.
There was a significant reduction in the percentage of individuals who were still receiving drug and non-drug pain treatments at 2 years (P <.01). The replacement group also reported comparable decreases in pain intensity after 2 years, indicating that SCS therapy is stable, with long-term effectiveness.
SCS-related adverse events (AEs) were similar to those reported in other studies, with a total of 242 (AEs) reported by 164 patients (40.8%). Most (AEs) occurred within 6 months of implantation. There were 31 individuals (8%) who experienced device deficiencies and revision surgery was necessary in 98 patients (24%). Of the AEs, 107 were considered serious (n=89 participants; 22%), with 23 (21%) and 49 (46%) AEs attributed to the procedure and the device, respectively.
Study strengths include a large sample size from multiple centers, the use of a multidisciplinary team, the inclusion of characteristic patients with pain, a low dropout rate (12%), good representation of all French implantation centers, and a real-life setting.
Study limitations include the heterogeneity of the primo group, possible responder rate underestimation, lack of a validated quality of life questionnaire, a qualitative assessment of medication, and reliance on patient recollection rather than a pain diary.
“This observational, prospective study…showed that tonic SCS was safe and effective in a representative sample of implanting sites in France,” concluded the authors.
This study was sponsored and funded by Medtronic.
PPL and CVdA are employees of Medtronic; EC, DF, PM and MCD are all consultants for Medtronic. DF is also a consultant for St Jude-Abbott and Autonomic Technologies. AB is a graduate of the St Jude European Neuromodulation Fellowship Program 2017.
Brinzeu A, Cuny E, Fontaine D, et al. Spinal cord stimulation for chronic refractory pain: long-term effectiveness and safety data from a multicentre registry [published online December 29, 2019]. Eur J Pain. doi:10.1002/ejp.1355