Does a screening trial for spinal cord stimulation in patients with chronic pain of neuropathic origin have clinical utility and cost-effectiveness? (TRIAL-STIM study): study protocol for a randomised controlled trial

Background: The TRIAL-STIM Study aims to assess the diagnostic performance, clinical outcomes and cost-effectiveness of a screening trial prior to full implantation of a spinal cord stimulation (SCS) device. Methods/design: The TRIAL-STIM Study is a superiority, parallel-group, three-centre, randomised controlled trial in patients with chronic neuropathic pain with a nested qualitative study and economic evaluation. The study will take place in three UK centres: South Tees Hospitals NHS Foundation Trust (The James Cook University Hospital); Basildon and Thurrock University Hospitals NHS Foundation Trust; and Leeds Teaching Hospitals NHS Trust. A total of 100 adults undergoing SCS implantation for the treatment of neuropathy will be included. Subjects will be recruited from the outpatient clinics of the three participating sites and randomised to undergo a screening trial prior to SCS implant or an implantation-only strategy in a 1:1 ratio. Allocation will be stratified by centre and minimised on patient age (≥ 65 or < 65 years), gender, presence of failed back surgery syndrome (or not) and use of high frequency (HF10™) (or not). The primary outcome measure is the numerical rating scale (NRS) at 6 months compared between the screening trial and implantation strategy and the implantation-only strategy. Secondary outcome measures will include diagnostic accuracy, the proportion of patients achieving at least 50% and 30% pain relief at 6 months as measured on the NRS, health-related quality-of-life (EQ-5D), function (Oswestry Disability Index), patient satisfaction (Patients’ Global Impression of Change) and complication rates. A nested qualitative study will be carried out in parallel for a total of 30 of the patients recruited in each centre (10 at each centre) to explore their views of the screening trial, implantation and overall use of the SCS device. The economic evaluation will take the form of a cost–utility analysis. Discussion: The TRIAL-STIM Study is a randomised controlled trial with a nested qualitative study and economic evaluation aiming to determine the clinical utility of screening trials of SCS as well as their cost-effectiveness. The nested qualitative study will seek to explore the patient’s view of the screening trials, implantation and overall use of SCS