Introduction

The National Institute for Health and Care Excellence (NICE) in United Kingdom recommends spinal cord stimulation (SCS) for adults with chronic neuropathic pain. NICE recommend an ‘SCS trial’ is used as the final step of a screening process to decide whether a patient should receive a permanent SCS implant. Whilst recommended in guidelines, little is known about the clinical utility or diagnostic accuracy of SCS screening trials. Funding from UK National Institute of Health Research (NIHR) enabled us to design a randomised controlled trial (RCT) aiming to:

Determine the diagnostic performance of SCS screening trial

Compare the outcomes and cost-effectiveness of an SCS trial strategy to an implantation only strategy

Assess the experiences and preferences of patients.

Methods/Materials

Subjects with neuropathic pain and candidates for SCS according to NICE guidance i.e. ≥6 months duration and ≥5 NRS pain score were recruited in 3 UK centres, and randomised 1:1 to undergo an SCS screening trial strategy (TG) or no trial implantation only strategy (NTG). The primary outcome measure was pain on NRS. Secondary outcome measures included the proportions achieving ≥50% ≥30% pain relief, health-related quality-of-life, function, patient satisfaction and complication rates. In addition to a health economic evaluation, a qualitative interview was conducted with a subset of participants.

Results

105 participants were randomised to TG (n=54), or NTG (n=51). There was good balance between TG and NTG participants at baseline. Pain NRS decreased from 7.47 at baseline to 4.28 at 6-months in TG and from 7.54 to 4.49 in NTG (mean group difference: 0.2, 95% CI: -1.2-0.9, p=0.89). We found no difference in the proportions reporting ≥50% pain relief between TG (36.6%) and NTG (39.6%) at six-month follow-up (odds ratio: 1.2, 95% CI: 0.4-1.7, P=0.73). Screening trials had 100% (95% CI: 78-100) sensitivity, 8% (95% CI: 1-25) specificity, with positive predictive value of 38% (95% CI: 36-41%). Costs of screening trial exceeded the implantation only strategy by £1,341/per participant. Qualitative analysis (n=27) showed overwhelming preference for no trial approach.

Discussion

This pragmatic independently funded RCT found that while a SCS screening trial may provide diagnostic utility there was no evidence to support that a screening trial strategy provides either better patient outcomes or cost-effectiveness versus an implantation only approach.

Conclusions

Patients expressed a strong preference for no screening trial.

NIHR funded this study. The funder had no role in study design, data collection, data analysis, interpretation of data.