Evaluation of the usability of the spinal cord stimulator recharging procedure in the treatment of neuropathic pain. A quantitative and qualitative study.

Background: Rechargeable stimulators have improved the management of patients treated with spinal cord stimulation by avoiding numerous interventions to replace stimulator devices whose batteries are reaching the end of their life. However, the recharging procedure can be restrictive for some patients and affect their satisfaction. Objective: The aim of this work is to evaluate the usability of the recharging procedure through a quantitative and qualitative approach to explore the experience of unsatisfied patients. Methods: The evaluation began with a retrospective analysis of 50 patients with neuropathic pain who have had a rechargeable spinal cord stimulator for more than one year. Patients completed the French version of the System Usability Scale (F-SUS) which is a scientifically validated usability questionnaire. Ten patients who were not satisfied with the recharging procedure (F-SUS score <70) has been interviewed and their speech has been analysed thematically. Results: These were 26 women and 24 men, mean age 51.6 years, operated on in 2019 and 2020 for spinal cord stimulation using a rechargeable stimulator for the treatment of neuropathic pain refractory to medical therapy. Forty patients (80% of cases) were satisfied (F-SUS score ≥70/100) and 10 patients not satisfied (F-SUS score <70) with the recharging procedure. The numerical pain scale improved by an average of 52% over the long term (mean follow-up 3.6 years). Rechargement time averaged 59.6 min (±35) and the interval between rechargement sessions 4.2 days (±7.1). These data were not significantly different between satisfied and not satisfied patient groups. The qualitative study revealed that the duration of the rechargement session was the main cause of dissatisfaction among unsatisfied patients. This is linked to the fact that these patients must remain virtually motionless throughout the session, otherwise recharging is interrupted by loss of contact between the recharging box and the stimulator. This study also highlights the fact that patients who have improved well with spinal cord stimulation are better able to tolerate the inconvenience of recharging, which is not the case for patients whose pain has improved little or not at all. Overall, patients would like to be better prepared for the recharging procedure. Conclusion: The mixed quantitative and qualitative analysis indicates that most patients are satisfied with the recharging procedure. The problem of contact between the recharging device and the stimulator device needs to be improved, as it is the main cause of dissatisfaction among patients who are not satisfied with the recharging procedure. Ethics and dissemination: This study was approved by the French ethics committee (CPP Est I ID RCB: 2022-A00683-40) on June 3, 2022, and registered on ClinicalTrials.gov (NCT05373654) on May 9, 2022.