Spinal cord stimulation trial-to-implant ratios: relic or requisite?

Abstract

The trial-to-implant ratio for spinal cord stimulation (SCS) has long served as a cornerstone metric for optimizing patient selection and cost containment. Historically, screening trials played a pivotal role in identifying non-responders, thereby minimizing unnecessary permanent implantations. The utility of the trial paradigm is supported by Medicare data from 2009, which reported a trial-to-implant ratio of 42.5%. However, advancements in SCS technology have significantly transformed the neuromodulation landscape and have been associated with higher rates of trial success. By 2018, the Medicare data showed trial-to-implant ratios exceeding 63%, with randomized clinical trials from 2020 to 2021 reporting ratios exceeding 80%-90%. These significant increases in trial-to-implant ratios suggest that only a minority of SCS candidates do not undergo a subsequent permanent device implantation. As such, re-evaluation of the trial-to-implant paradigm, from the perspective of practicing pain physicians in the USA, in light of evolving clinical practices and economic pressures, is warranted. This discourse explores the benefits and limitations of the trial-to-implant ratio, emphasizing its role as a safeguard against overutilization and a tool for standardizing clinical practices but weighed against its shortcomings including a lack of alignment with long-term outcomes, underscore the need for alternative metrics that include per capita trial utilization and explant-to-implant ratios. European responses to similar questions have resulted in utilizing validated symptom screening tools and direct-to-implant pathways in lieu of a screening trial altogether as potential strategies to optimize SCS utilization while maintaining cost-effectiveness. As healthcare systems adapt to advancements in neuromodulation, a balanced perspective on trial-to-implant ratios and complementary metrics is essential to ensure equitable access, sustainable outcomes and evidence-based care for the future of SCS therapy.