Karri, Jay

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.

Background A growing number of meta-analyses (MA) have investigated the use of spinal cord stimulation (SCS) as a treatment modality for chronic pain. The quality of these MAs has not been assessed by validated appraisal tools. Objective To examine the methodological characteristics and quality of MAs related to the use of SCS for chronic pain syndromes. Evidence review An online literature search was conducted in Ovid MEDLINE(R), Ovid EMBASE, Ovid Cochrane Database of Systematic Reviews, and Scopus databases (January 1, 2000 through June 30, 2023) to identify MAs that investigated changes in pain intensity, opioid consumption, and/or physical function after SCS for the treatment of chronic pain. MA quality was assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) critical appraisal tool. Findings Twenty-five MAs were appraised in the final analysis. Three were considered “high” quality, three “low” quality, and 19 “critically low” quality, per the AMSTAR-2 criteria. There was no association between the publication year and AMSTAR-2 overall quality (β 0.043; 95% CI −0.008 to 0.095; p=0.097). There was an association between the impact factor and AMSTAR-2 overall quality (β 0.108; 95% CI 0.044 to 0.172; p=0.002), such that studies published in journals with higher impact factors were associated with higher overall quality. There was no association between the effect size and AMSTAR-2 overall quality (β −0.168; 95% CI −0.518 to 0.183; p=0.320). According to our power analysis, three studies were adequately powered (>80%) to reject the null hypothesis, while the remaining studies were underpowered (<80%). Conclusions The study demonstrates a critically low AMSTAR-2 quality for most MAs published on the use of SCS for treating chronic pain. Future MAs should improve study quality by implementing the AMSTAR-2 checklist items. PROSPERO registration number CRD42023431155.