Network Meta-analysis and Economic Evaluation of Neurostimulation Interventions for Chronic Non-surgical Refractory back Pain.

OBJECTIVES: Different types of spinal cord stimulation (SCS) have now been evaluated for the management of chronic non-surgical refractory back pain (NSRBP). A direct comparison between the different types of SCS or between closed-loop SCS with conventional medical management (CMM) for patients with NSRBP has not been previously conducted, and therefore, their relative effectiveness and cost-effectiveness remain unknown. The aim of this study was to perform a systematic review, network meta-analysis (NMA) and economic evaluation of closed-loop SCS compared with fixed-output SCS and CMM for patients with NSRBP. METHODS: Databases were searched to 8th September 2023. Randomised controlled trials of SCS for NSRBP were included. Results of studies were combined using fixed-effect NMA models. A cost-utility analysis was performed from the perspective of the UK National Health Service with results reported as incremental cost per quality-adjusted life-year (QALY). RESULTS: Closed-loop SCS resulted in statistically and clinically significant reductions in pain intensity (mean difference [MD] 32.72 [95% CrI 15.69-49.78]) and improvements in secondary outcomes compared to fixed-output SCS at 6-months follow-up. Compared to CMM, both closed-loop and fixed-output SCS result in statistically and clinically significant reductions in pain intensity (closed-loop SCS vs. CMM MD 101.58 [95% CrI 83.73-119.48]; fixed-output SCS versus CMM MD 68.86 [95% CrI 63.43-74.31]) and improvements in secondary outcomes. Cost-utility analysis shows that closed-loop SCS dominates fixed-output SCS and CMM, and fixed-output SCS also dominates CMM. DISCUSSION: Current evidence shows that closed-loop and fixed-output SCS provide more benefits and are cost-saving compared to CMM for patients with NSRBP.

Clinical study of a micro-implantable pulse generator for the treatment of peripheral neuropathic pain: 3-month and 6-month results from the COMFORT-randomised controlled trial.

BACKGROUND: We report the results from the first large, postmarket, multicentre, randomised controlled trial (RCT) evaluating peripheral nerve stimulation (PNS) for the treatment of chronic peripheral pain with a micro-implantable pulse generator (micro-IPG). METHODS: Subjects meeting eligibility were randomised (2:1) to either the active arm receiving PNS and conventional medical management (CMM) or the control arm receiving CMM alone. Treatments were limited to the following areas: lower back, shoulder, knee and foot/ankle. RESULTS: At 6 months, the active arm achieved an 88% responder rate with a 70% average reduction in pain. At the 3-month primary endpoint, the active arm achieved an 84% responder rate with an average pain reduction of 67% compared with the control arm, which achieved a 3% responder rate with an average pain reduction of 6%. Both responder rate and pain reduction in the active arm were significantly better than in the control arm (p<0.001). A majority of patient-reported outcomes also reached statistical significance. There have been no reports of pocket pain and no serious adverse device effects. 81% of subjects found the external wearable component of the PNS system to be comfortable. CONCLUSIONS: This study successfully reached its primary endpoint-the active arm achieved a statistically significant superior responder rate as compared with the control arm at 3 months. These RCT results demonstrated that PNS, with this micro-IPG, is efficacious and safe. This ongoing study will follow subjects for 3 years, the results of which will be reported as they become available.

Neurophysiological outcomes that sustained clinically significant improvements over 3 years of physiologic ECAP-controlled closed-loop spinal cord stimulation for the treatment of chronic pain.

INTRODUCTION: A novel, spinal cord stimulation (SCS) system with a physiologic closed-loop (CL) feedback mechanism controlled by evoked compound action potentials (ECAPs) enables the optimization of physiologic neural dose and the accuracy of the stimulation, not possible with any other commercially available SCS systems. The report of objective spinal cord measurements is essential to increase the transparency and reproducibility of SCS therapy. Here, we report a cohort of the EVOKE double-blind randomized controlled trial treated with CL-SCS for 36 months to evaluate the ECAP dose and accuracy that sustained the durability of clinical improvements. METHODS: 41 patients randomized to CL-SCS remained in their treatment allocation and were followed up through 36 months. Objective neurophysiological data, including measures of spinal cord activation, were analyzed. Pain relief was assessed by determining the proportion of patients with ≥50% and ≥80% reduction in overall back and leg pain. RESULTS: The performance of the feedback loop resulted in high-dose accuracy by keeping the elicited ECAP within 4µV of the target ECAP set on the system across all timepoints. Percent time stimulating above the ECAP threshold was >98%, and the ECAP dose was ≥19.3µV. Most patients obtained ≥50% reduction (83%) and ≥80% reduction (59%) in overall back and leg pain with a sustained response observed in the rates between 3-month and 36-month follow-up (p=0.083 and p=0.405, respectively). CONCLUSION: The results suggest that a physiological adherence to supra-ECAP threshold therapy that generates pain inhibition provided by ECAP-controlled CL-SCS leads to durable improvements in pain intensity with no evidence of loss of therapeutic effect through 36-month follow-up.

Durable multimodal and holistic response for physiologic closed-loop spinal cord stimulation supported by objective evidence from the EVOKE double-blind randomized controlled trial.

INTRODUCTION: Chronic pain patients may experience impairments in multiple health-related domains. The design and interpretation of clinical trials of chronic pain interventions, however, remains primarily focused on treatment effects on pain intensity. This study investigates a novel, multidimensional holistic treatment response to evoked compound action potential-controlled closed-loop versus open-loop spinal cord stimulation as well as the degree of neural activation that produced that treatment response. METHODS: Outcome data for pain intensity, physical function, health-related quality of life, sleep quality and emotional function were derived from individual patient level data from the EVOKE multicenter, participant, investigator, and outcome assessor-blinded, parallel-arm randomized controlled trial with 24 month follow-up. Evaluation of holistic treatment response considered whether the baseline score was worse than normative values and whether minimal clinical important differences were reached in each of the domains that were impaired at baseline. A cumulative responder score was calculated to reflect the total minimal clinical important differences accumulated across all domains. Objective neurophysiological data, including spinal cord activation were measured. RESULTS: Patients were randomized to closed-loop (n=67) or open-loop (n=67). A greater proportion of patients with closed-loop spinal cord stimulation (49.3% vs 26.9%) were holistic responders at 24-month follow-up, with at least one minimal clinical important difference in all impaired domains (absolute risk difference: 22.4%, 95% CI 6.4% to 38.4%, p=0.012). The cumulative responder score was significantly greater for closed-loop patients at all time points and resulted in the achievement of more than three additional minimal clinical important differences at 24-month follow-up (mean difference 3.4, 95% CI 1.3 to 5.5, p=0.002). Neural activation was three times more accurate in closed-loop spinal cord stimulation (p<0.001 at all time points). CONCLUSION: The results of this study suggest that closed-loop spinal cord stimulation can provide sustained clinically meaningful improvements in multiple domains and provide holistic improvement in the long-term for patients with chronic refractory pain. TRIAL REGISTRATION NUMBER: NCT02924129.

Device profile of the Evoke physiologic closed-loop spinal cord stimulation system for the treatment of chronic intractable pain: overview of its safety and efficacy.

INTRODUCTION: The Evoke® spinal cord stimulation (SCS) device enables the closed-loop feedback of dynamically measured evoked compound action potentials (ECAPs) to adjust stimulation amplitude for every stimulation pulse to maintain the stimulation output level near a targeted ECAP amplitude. No other commercially available SCS device presently uses physiologic feedback from the spinal cord to adjust stimulation. Clinicians should be familiar with the differences in devices and with the latest technologies to provide optimized patient care. AREAS COVERED: In this device profile, the Evoke system is described and the system capabilities are differentiated from other available SCS devices. A systematic review was conducted based on best practice guidance to identify all available evidence on the safety and efficacy of the Evoke SCS system. EXPERT OPINION: The Evoke SCS system offers unique capabilities as a means to optimize therapy delivery tailored to each individual patient. Data through 24-months follow-up show statistically significant, clinically meaningful, ample, consistent, and strong evidence of the safety and efficacy of the Evoke system for the treatment of chronic intractable pain.

ECAP-controlled closed-loop versus open-loop SCS for the treatment of chronic pain: 36-month results of the EVOKE blinded randomized clinical trial.

INTRODUCTION: The evidence for spinal cord stimulation (SCS) has been criticized for the absence of blinded, parallel randomized controlled trials (RCTs) and limited evaluations of the long-term effects of SCS in RCTs. The aim of this study was to determine whether evoked compound action potential (ECAP)-controlled, closed-loop SCS (CL-SCS) is associated with better outcomes when compared with fixed-output, open-loop SCS (OL-SCS) 36 months following implant. METHODS: The EVOKE study was a multicenter, participant-blinded, investigator-blinded, and outcome assessor-blinded, randomized, controlled, parallel-arm clinical trial that compared ECAP-controlled CL-SCS with fixed-output OL-SCS. Participants with chronic, intractable back and leg pain refractory to conservative therapy were enrolled between January 2017 and February 2018, with follow-up through 36 months. The primary outcome was a reduction of at least 50% in overall back and leg pain. Holistic treatment response, a composite outcome including pain intensity, physical and emotional functioning, sleep, and health-related quality of life, and objective neural activation was also assessed. RESULTS: At 36 months, more CL-SCS than OL-SCS participants reported ≥50% reduction (CL-SCS=77.6%, OL-SCS=49.3%; difference: 28.4%, 95% CI 12.8% to 43.9%, p<0.001) and ≥80% reduction (CL-SCS=49.3%, OL-SCS=31.3%; difference: 17.9, 95% CI 1.6% to 34.2%, p=0.032) in overall back and leg pain intensity. Clinically meaningful improvements from baseline were observed at 36 months in both CL-SCS and OL-SCS groups in all other patient-reported outcomes with greater levels of improvement with CL-SCS. A greater proportion of patients with CL-SCS were holistic treatment responders at 36-month follow-up (44.8% vs 28.4%), with a greater cumulative responder score for CL-SCS patients. Greater neural activation and accuracy were observed with CL-SCS. There were no differences between CL-SCS and OL-SCS groups in adverse events. No explants due to loss of efficacy were observed in the CL-SCS group. CONCLUSION: This long-term evaluation with objective measurement of SCS therapy demonstrated that ECAP-controlled CL-SCS resulted in sustained, durable pain relief and superior holistic treatment response through 36 months. Greater neural activation and increased accuracy of therapy delivery were observed with ECAP-controlled CL-SCS than OL-SCS. TRIAL REGISTRATION NUMBER: NCT02924129.

Cost-utility Analysis of Evoke Closed-loop Spinal Cord Stimulation for Chronic Back and Leg Pain.

OBJECTIVES: The effectiveness of Evoke closed-loop spinal cord stimulation (CL-SCS), a novel modality of neurostimulation, has been demonstrated in a randomized controlled trial (RCT). The objective of this cost-utility analysis was to develop a de novo economic model to estimate the cost-effectiveness of Evoke CL-SCS when compared with open-loop SCS (OL-SCS) for the management of chronic back and leg pain. METHODS: A decision tree followed by a Markov model was used to estimate the costs and outcomes of Evoke CL-SCS versus OL-SCS over a 15-year time horizon from the UK National Health Service perspective. A "high-responder" health state was included to reflect improved levels of SCS pain reduction recently reported. Results are expressed as incremental cost per quality-adjusted life year (QALY). Deterministic and probabilistic sensitivity analysis (PSA) was conducted to assess uncertainty in the model inputs. RESULTS: Evoke CL-SCS was estimated to be the dominant treatment strategy at ~5 years postimplant (ie, it generates more QALYs while cost saving compared with OL-SCS). Probabilistic sensitivity analysis showed that Evoke CL-SCS has a 92% likelihood of being cost-effective at a willingness to pay threshold of £20,000/QALY. Results were robust across a wide range of scenario and sensitivity analyses. DISCUSSION: The results indicate a strong economic case for the use of Evoke CL-SCS in the management of chronic back and leg pain with or without prior spinal surgery with dominance observed at ~5 years.

Percutaneous image-guided lumbar decompression and interspinous spacers for the treatment of lumbar spinal stenosis: A 2-year Medicare Claims Benchmark Study.

OBJECTIVE: This prospective longitudinal study compares outcomes between Medicare beneficiaries receiving percutaneous image-guided lumbar decompression (PILD) using the mild® procedure and a control group of patients receiving interspinous spacers for the treatment of lumbar spinal stenosis (LSS) with neurogenic claudication (NC). METHODS: Patients diagnosed with LSS with NC and treated with either the mild procedure or a spacer were identified in the Medicare claims database. The incidence of harms, the rate of subsequent interventions, and the overall combined rate of harms and subsequent interventions during 2-year follow-up after the index procedure were compared between the two groups and assessed for statistical significance with p = 0.05. RESULTS: The study included 2229 patients in the mild group and 3401 patients who were implanted with interspinous spacers. The rate of harms for those treated with the mild procedure was less than half that of patients implanted with a spacer (5.6% vs. 12.1%, respectively; p < 0.0001) during 2-year follow-up. The rate of subsequent interventions was not significantly different between the two groups (24.9% and 26.1% for the mild and spacer groups, respectively; p = 0.7679). The total rate of harms and subsequent interventions for mild was found to be noninferior to spacers (p < 0.0001). CONCLUSIONS: This comprehensive study of real-world Medicare claims data demonstrated a significantly lower rate of harms for the mild procedure compared to interspinous spacers for patients diagnosed with LSS with NC, and a similar rate of subsequent interventions during 2-year follow-up.

Effect of Provider Specialty on Medical Resource Utilization and Costs in Chronic Spinal-Pain Management.

BACKGROUND: Poorly managed chronic spinal pain encumbers medical resources and drives healthcare costs, suggesting a target for improvement. OBJECTIVES: To determine how specialist-care pathways influence healthcare costs in the first year after a referral for chronic spine pain. STUDY DESIGN: This was a retrospective cohort analysis of administrative claims from a large commercial health insurance provider, analyzing a 6-month baseline, a variable "pre-referral period," and a one-year period of specialist care. SETTING: US patients covered by private commercial insurers. METHODS: Adult patients diagnosed with chronic, spine-related pain between July 2016 and February 2018 and under the active care of a specialist were eligible. Patients with neurological deficits or cancer-related pain were excluded. Patients were categorized based on sequence-dependent exposure to a pain specialist, a surgeon, or both specialties. Key measures were pain-related and all-cause medical resource use and costs and opioid prescription fills. RESULTS: Of 306,080 eligible patients (mean age 61.6; 61.5% women), 13% saw a pain specialist, 71% a surgeon, 7% a pain specialist then a surgeon, and 9% a surgeon then a pain specialist. Referral to a pain specialist alone was associated with lower resource use and per-patient adjusted cost savings of $3,311 (pain-related) and $6,447 (all-cause) compared to patients referred to a surgeon alone. The pain specialist pathway was associated with increased indicators of prescription opioid use. LIMITATIONS: Cohort design constraints temper the results' generalizability, given the need to simultaneously examine specialty pathway and medical resource incurred over the same time period. CONCLUSIONS: We observed meaningful savings in cost and resource use when chronic spine-pain patients were managed by pain specialists. Pain-management referrals should be an element of a thoughtfully designed care pathway.

Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation.

BACKGROUND: Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity. AIM: The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response". DISCUSSION: Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.

Association Between Levels of Functional Disability and Health-Related Quality of Life With Spinal Cord Stimulation for Chronic Pain.

OBJECTIVES: Pain score, functional disability, and health-related quality of life (HRQoL) are core outcome domains for chronic pain clinical trials. Although greater levels of pain reduction have been shown to be linked to larger gains in HRQoL, little is known of the association between HRQoL and disability in the setting of chronic pain. The aims of this study were to 1) investigate the association between functional disability and HRQoL and 2) estimate the utility values associated with levels of functional disability in patients treated with evoked compound action potential (ECAP) spinal cord stimulation (SCS) for chronic pain. MATERIALS AND METHODS: Data on functional disability assessed using the Oswestry Disability Index (ODI) and HRQoL (EQ-5D-5L) were collected from 204 patients with an Evoke ECAP-SCS device and followed up to 12 months. SF-6D utility scores also were retrieved for 134 of these patients. Multivariable linear regression models adjusted for baseline utility values and patient demographics were used to compare differences in utility values across ODI categories. RESULTS: Significant improvements in functional disability and HRQoL were observed at three- and 12-month follow-up after SCS. Patients reporting "minimum disability," "moderate disability," "severe disability," and "crippled" had mean EQ-5D scores of 0.82, 0.73, 0.59, and 0.45, respectively. The mean change in EQ-5D score was 0.007 per unit change in total ODI score. The R2 statistic showed a moderate level association (49%-64% of variance in EQ-5D explained by ODI). CONCLUSION: ECAP-SCS results in significant improvements in functional disability and HRQoL. This study shows that improvement in function of people with chronic pain before and after ECAP-SCS is associated with improvement in HRQoL.

Comparative Systematic Review and Meta-Analysis of Cochrane Review of Epidural Injections for Lumbar Radiculopathy or Sciatica.

BACKGROUND: Epidural injections are among the most commonly performed procedures for managing low back and lower extremity pain. Pinto et al and Chou et al previously performed systematic reviews and meta-analyses, which, along with a recent update from Oliveira et al showing the lack of effectiveness of epidural steroid injections in managing lumbar disc herniation, spinal stenosis, and radiculopathy. In contrast to these papers, multiple other systematic reviews and meta-analyses have supported the effectiveness and use of epidural injections utilizing fluoroscopically guided techniques. A major flaw in the review can be related to attributing active-controlled trials to placebo-controlled trials. The assumption that local anesthetics do not provide sustained benefit, despite extensive evidence that local anesthetics provide long-term relief, similar to a combination of local anesthetic with steroids is flawed. STUDY DESIGN: The Cochrane Review of randomized controlled trials (RCTs) of epidural injections in managing chronic low back and lower extremity pain with sciatica or lumbar radiculopathy were reanalyzed using systematic methodology and meta-analysis. OBJECTIVES: To re-evaluate Cochrane data on RCTs of epidural injections in managing chronic low back and lower extremity pain with sciatica or lumbar radiculopathy utilizing qualitative and quantitative techniques with dual-arm and single-arm analysis. METHODS: In this systematic review, we have used the same RCTs from the Cochrane Review of a minimum of 20% change in pain scale or significant pain relief of >= 50%. The outcome measures were pain relief and functional status improvement. Significant improvement was defined as 50% or greater pain relief and functional status improvement. Our review was performed utilizing the Cochrane Review methodologic quality assessment and the Interventional Pain Management Techniques - Quality Appraisal of Reliability and Risk of Bias Assessment (IPM-QRB). Evidence was summarized utilizing the principles of best evidence synthesis and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system. Clinical relevance of the pragmatic nature of each study was assessed. RESULTS: In evaluating the RCTs in the Cochrane Review, 10 trials were performed with fluoroscopic guidance. Utilizing conventional dual-arm and single-arm meta-analysis, the evidence is vastly different from the interpretation of the data within the Cochrane Review. The overall combined evidence is Level I, or strong evidence, at one and 3 months, and Level II, or moderate evidence, at 6 and 12 months. LIMITATIONS: The limitation of this study is that only data contained in the Cochrane Review were analyzed. CONCLUSION: A comparative systematic review and meta-analysis of the Cochrane Review of randomized controlled trials (RCTs) of epidural injections in managing chronic low back and lower extremity pain with sciatica or lumbar radiculopathy yielded different results. This review, based on the evidence derived from placebo-controlled trials and active-controlled trials showed Level I, or strong evidence, at one and 3 months and Level II at 6 and 12 months. This review once again emphasizes the importance of the allocation of studies to placebo-control and active-control groups, utilizing standards of practice with inclusion of only the studies performed under fluoroscopic guidance.

Fourth Wave of Opioid (Illicit Drug) Overdose Deaths and Diminishing Access to Prescription Opioids and Interventional Techniques: Cause and Effect.

BACKGROUND: In the midst of the COVID-19 pandemic, data has shown that age-adjusted overdose death rates involving synthetic opioids, psychostimulants, cocaine, and heroin have been increasing, including prescription opioid deaths, which were declining, but, recently, reversing the trends. Contrary to widely held perceptions, the problem of misuse, abuse, and diversion of prescription opioids has been the least of all the factors in recent years. Consequently, it is important to properly distinguish between the role of illicit and prescription opioids in the current opioid crisis. Multiple efforts have been based on consensus on administrative policies for certain harm reduction strategies for individuals actively using illicit drugs and reducing opioid prescriptions leading to curbing of medically needed opioids, which have been ineffective. While there is no denial that prescription opioids can be misused, abused, and diverted, the policies have oversimplified the issue by curbing prescription opioids and the pendulum has swung too far in the direction of severely limiting prescription opioids, without acknowledgement that opioids have legitimate uses for persons suffering from chronic pain. Similar to the opioid crisis, interventional pain management procedures have been affected by various policies being applied to reduce overuse, abuse, and finally utilization. Medical policies have been becoming more restrictive with reduction of access to certain procedures, with the pendulum swinging too far in the direction of limiting interventional techniques. Recent utilization assessments have shown a consistent decline for most interventional techniques, with a 18.7% decrease from 2019 to 2020. The causes for these dynamic changes are multifactorial likely including the misapplication of the 2016 Centers for Disease Control and Prevention (CDC) guidelines for prescribing opioids for chronic pain, the relative ease of access to illicit synthetic opioids and more recently issues related to the COVID-19 pandemic. In addition, recent publications have shown association of dose tapering with overdose or mental health crisis among patients prescribed long-term opioids. These findings are leading to the hypothesis that federal guidelines may inadvertently be contributing to an increase in overall opioid deaths and diminished access to interventional techniques. Together, these have resulted in a fourth wave of the opioid epidemic. METHODS: A narrative review. RESULTS: The fourth wave results from a confluence of multiple factors, including misapplication of CDC guidelines, the increased availability of illicit drugs, the COVID-19 pandemic, and policies reducing access to interventional procedures. The CDC guidelines and subsequent regulatory atmosphere have led to aggressive tapering up to and including, at times, the overall reduction or stoppage of opioid prescriptions. Forced tapering has been linked to an increase of 69% for overdoses and 130% for mental health crisis. The data thus suggests that the diminution in access to opioid prescriptions may be occurring simultaneously with an increase in illicit narcotic use.Combined with CDC guidelines, the curbing of opioid prescriptions to medically needed individuals, among non-opioid treatments, interventional techniques have been affected with declining utilization rates and medical policies reducing access to such modalities. CONCLUSION: The opioid overdose waves over the past three decades have resulted from different etiologies. Wave one was associated with prescription opioid overdose deaths and wave two with the rise in heroin and overdose deaths from 1999 to 2013. Wave three was associated with a rise in synthetic opioid overdose deaths. Sadly, wave four continues to escalate with increasing number of deaths as a confluence of factors including the CDC guidelines, the COVID pandemic, increased availability of illicit synthetic opioids and the reduction of access to interventional techniques, which leads patients to seek remedies on their own.

Durability of Clinical and Quality-of-Life Outcomes of Closed-Loop Spinal Cord Stimulation for Chronic Back and Leg Pain: A Secondary Analysis of the Evoke Randomized Clinical Trial.

Importance: Chronic pain is debilitating and profoundly affects health-related quality of life. Spinal cord stimulation (SCS) is a well-established therapy for chronic pain; however, SCS has been limited by the inability to directly measure the elicited neural response, precluding confirmation of neural activation and continuous therapy. A novel SCS system measures the evoked compound action potentials (ECAPs) to produce a real-time physiological closed-loop control system. Objective: To determine whether ECAP-controlled, closed-loop SCS is associated with better outcomes compared with fixed-output, open-loop SCS at 24 months following implant. Design, Setting, and Participants: The Evoke study was a double-blind, randomized, controlled, parallel arm clinical trial with 36 months of follow-up. Participants were enrolled from February 2017 to 2018, and the study was conducted at 13 US investigation sites. SCS candidates with chronic, intractable back and leg pain refractory to conservative therapy, who consented, were screened. Key eligibility criteria included overall, back, and leg pain visual analog scale score of 60 mm or more; Oswestry Disability Index score of 41 to 80; stable pain medications; and no previous SCS. Analysis took place from October 2020 to April 2021. Interventions: ECAP-controlled, closed-loop SCS was compared with fixed-output, open-loop SCS. Main Outcomes and Measures: Reported here are the 24-month outcomes of the trial, which include all randomized patients in the primary and safety analyses. The primary outcome was a reduction of 50% or more in overall back and leg pain assessed at 3 and 12 months (previously published). Results: Of 134 randomized patients, 65 (48.5%) were female and the mean (SD) age was 55.2 (10.6) years. At 24 months, significantly more closed-loop than open-loop patients were responders (≥50% reduction) in overall pain (53 of 67 [79.1%] in the closed-loop group; 36 of 67 [53.7%] in the open-loop group; difference, 25.4% [95% CI, 10.0%-40.8%]; P = .001). There was no difference in safety profiles between groups (difference in rate of study-related adverse events: 6.0 [95% CI, -7.8 to 19.7]). Improvements were also observed in health-related quality of life, physical and emotional functioning, and sleep, in parallel with opioid reduction or elimination. Objective neurophysiological measurements substantiated the clinical outcomes and provided evidence of activation of inhibitory pain mechanisms. Conclusions and Relevance: ECAP-controlled, closed-loop SCS, which elicited a more consistent neural response, was associated with sustained superior pain relief at 24 months, consistent with the 3- and 12-month outcomes.

Healthcare Utilization and Costs Associated with New-Onset Pain in a Medicare Population.

BACKGROUND: Chronic pain is a common and growing problem in the United States with variable strategies for its treatment. Surgical interventions are necessary in some cases but not required for all patients with new-onset pain. For some patients, interventional pain management (IPM) techniques can treat chronic pain without the cost or risk associated with surgical intervention. OBJECTIVE: The objective of this study was to compare healthcare utilization and costs for new-onset chronic pain treated by IPM specialists to those treated by providers with surgical specialties (i.e., orthopedists and neurosurgeons). STUDY DESIGN: This was a retrospective observational study of qualifying patients over 36-months (2016-2019). SETTING: This study was conducted using 100% Medicare FFS Parts A, B, and Prescription Drug Event (PDE) Part D data, including enrollment and claims. METHODS: Patients with a diagnosis of pain were identified in the claims data. Twelve months of pre-period claims were examined to ensure the incident diagnosis of pain, and 2 additional pain diagnoses were required after initial diagnosis. Patients were assigned either to the IPM cohort or a Surgical cohort based on the specialty of the provider involved in their first pain-related visit after initial diagnosis. Key outcomes, such as the utilization of healthcare services and cost of care, were evaluated for both cohorts over the 24-months following the index diagnosis of pain. RESULTS: 106,658 beneficiaries were included in the study with roughly 36% in the IPM cohort. Patients in the IPM cohort were less healthy and had lower incomes in the baseline period compared to the Surgical cohort. Fewer members of the IPM cohort had an inpatient stay in the 24-months post index pain diagnosis (40% compared to 43% in the surgery cohort) and the IPM cohort had fewer patients with a post-acute care stay (29% compared to 31% in the inpatient stay cohort). The IPM cohort had lower risk-adjusted total costs of care than the Surgical cohort, driven by lower inpatient, outpatient, and post-acute care costs. LIMITATIONS: Retrospective claims data may not include some factors important to patients with a pain diagnosis (such as over-the-counter medications, holistic treatments, or pain scores). CONCLUSION(S): By shifting patients from higher-cost and more invasive surgical procedures, IPM's multidisciplinary approach to pain treatment can reduce surgical utilization and costs for certain chronic pain patients. This shift away from more expensive surgical treatments fits well with Medicare's move toward value-based care, driven by a focus on patient outcomes including health care utilization and costs.

The Cost of Lost Productivity in an Opioid Utilizing Pain Sample.

BACKGROUND AND AIMS: Chronic pain affects more adults in the United States than any other condition. Opioid medications are widely used in the treatment of chronic pain, but there remains considerable risk and cost associated with their use. This study aims to characterize the effects of opioid prescribing for chronic pain and similar pain conditions on lost productivity in the United States. METHODS: This was a retrospective, longitudinal, observational study of chronic pain patients in 2011-2014. We identified patients with a diagnosis of musculoskeletal pain receiving index prescription for opioids in administrative claims and studied disability absence in a linked health and productivity management database. Patients were grouped as de novo and continued use opioid users before index, and by opioid dose in the year after index. Days of disability were compared before and after index with bootstrapping. Effect of opioid dose group on disability was evaluated with negative binomial regression. Lost productivity cost was compared before and after index. RESULTS: The cohort contained 16,273 de novo and 6604 continued use patients. On average, de novo patients used 24.8 days of disability after index, an increase of 18.3 more days compared to before (p < 0.001). Continued use patients used 30.7 days after index, 9 more days than before (p < 0.001). There was a dose-response relationship between dose group and days of disability in de novo patients (p < 0.001). The weighted-average cost per person of lost productivity was $4344 higher in the year after index compared to the year before. CONCLUSION: Opioid prescriptions for pain patients were associated with significant disability use and lost productivity costs. With the evolution of opioid-prescribing practices, CDC recommendations, and the HHS Pain Management Best Practices, there is opportunity to use alternative pain therapies without the risks of opioid-induced side effects to improve work productivity.

Peripherally Induced Reconditioning of the Central Nervous System: A Proposed Mechanistic Theory for Sustained Relief of Chronic Pain with Percutaneous Peripheral Nerve Stimulation.

Peripheral nerve stimulation (PNS) is an effective tool for the treatment of chronic pain, although its efficacy and utilization have previously been significantly limited by technology. In recent years, purpose-built percutaneous PNS devices have been developed to overcome the limitations of conventional permanently implanted neurostimulation devices. Recent clinical evidence suggests clinically significant and sustained reductions in pain can persist well beyond the PNS treatment period, outcomes that have not previously been observed with conventional permanently implanted neurostimulation devices. This narrative review summarizes mechanistic processes that contribute to chronic pain, and the potential mechanisms by which selective large diameter afferent fiber activation may reverse these changes to induce a prolonged reduction in pain. The interplay of these mechanisms, supported by data in chronic pain states that have been effectively treated with percutaneous PNS, will also be discussed in support of a new theory of pain management in neuromodulation: Peripherally Induced Reconditioning of the Central Nervous System (CNS).