Composite outcomes for pain clinical trials: considerations for design and interpretation

The Added Value of Digital Body Chart Pain Surface Assessment as an Objective Biomarker: Multicohort Study

BACKGROUND

Although it has been well-documented that pain intensity alone is not sufficient to assess chronic pain, the objective pain surface encapsulated in a digital tool might present a major interest in the objective assessment of pain.

OBJECTIVE

This study aims to determine the potential added value of pain surface measurement by determining the correlation between pain surface and pain intensity in chronic pain patients.

METHODS

Two databases from observational prospective and retrospective longitudinal studies including patients with chronic pain were used in this research. Pain intensity was assessed by the Numeric Pain Rating Scale. Pain surface (cm²) and pain typology (neuropathic vs mechanical components) were measured by a specific pain mapping digital tool (PRISMap, Poitiers University Hospital). Patients were asked to draw their pain surface on a computerized tactile interface in a predetermined body (adapted from the patient's BMI). A color code was used to represent pain intensity (very intense, intense, moderate, and low). Simple linear regression was used to assess the proportion of variance in pain surface explained by pain intensity.

RESULTS

The final analysis included 637 patients with chronic pain. The percentage of variance of the pain surface explained by pain intensity was 1.24% (R²=0.0124; 95% CI 0.11%-6.3%). In addition, 424 (66.6%) patients used more than 1 intensity or color, among whom 218 (34.2%) used 2 intensities or colors, 155 (24.3%) used 3 intensities or colors, and 51 (8%) used 4 intensities or colors.

CONCLUSIONS

This study showed that pain intensity and pain surface provide complementary and distinct information that would help to improve pain assessment. Two-thirds of the cohort used 2 or more intensities to describe their pain. Combining pain intensity and pain surface should be strongly considered as a means of improving daily practice assessment of patients with chronic pain in primary and secondary care.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02964130; https://clinicaltrials.gov/study/NCT02964130?term=PREDIBACK&rank=2.

Multidimensional pain assessment and opioid use after total knee arthroplasty: continuous vs single-injection regional vs systemic analgesia

Introduction

Effective pain management after total knee arthroplasty (TKA) is essential for recovery. Continuous peripheral nerve blocks (PNBc) are often believed to provide superior pain relief compared with single-injection peripheral nerve blocks (PNBs). However, multidimensional pain-related patient-reported outcomes (PROs) have not been extensively studied.

Objective

Based on registry data, this study compared pain intensities summarized as a pain composite score (PCS) and postoperative opioid use between PNBc and PNBs nerve blocks in patients undergoing TKA, and evaluated additional PROs.

Methods

Data from 4,328 adults undergoing TKA enrolled in the PAIN OUT registry (ClinicalTrials.gov NCT02083835) were analyzed. Patients were categorized into general anesthesia (GA) or spinal anesthesia (SA), with subgroups general anesthesia only (GA-o) or spinal anesthesia only (SA-o), and combinations with single-injection PNB (GA&PNBs and SA&PNBs) or continuous PNB via catheter (GA&PNBc and SA&PNBc). The primary end point was PCS, summarizing pain intensities and time in severe pain during the first 24 hours. Secondary end points included opioid use and additional PROs.

Results

The use of GA&PNBc was associated with a higher PCS (+0.5 [0.0-0.9], P = 0.035) compared with GA&PNBs, while PCS was similar between SA&PNBs and SA&PNBc. Opioid use was more frequent in GA&PNBc (+20.3%) and SA&PNBc (+50.8%) compared with the respective PNBs groups (P < 0.001). Patient-reported outcomes were higher in PNBc groups (median score 3.2 vs 2.7-2.9 in other groups; P < 0.001).

Conclusion

Continuous PNBc showed no clear advantage over PNBs in pain relief, opioid use, or further PROs. Future research should incorporate comprehensive PROs to better evaluate analgesic techniques in TKA.

Chronic postsurgical pain in the ICD-11: implications for anaesthesiology and pain medicine

Chronic postsurgical pain (CPSP) is associated with reduced health-related quality of life and disability. In some patients, it can result in long-term opioid use even after minor surgery. Epidemiological studies have reported highly varying rates of CPSP, largely because researchers have used different definitions with self-defined cut-offs for pain scores. With the introduction of the 11th revision of the World Health Organisation International Classification of Diseases and Related Health Problems (ICD-11), chronic pain is now recognised as an entity of its own, its biopsychosocial nature is emphasised, and its definition is standardised. Compared with the ICD-11 definition, the prevalence of CPSP might have been overestimated in previous studies. The ICD-11 provides a multifactorial assessment of pain severity, referring to pain intensity, pain-related interference, and pain-related distress, which cover the biopsychosocial aspects of chronic pain. These three scores can be added as extension codes to any pain diagnosis. Harmonisation of the CPSP criteria within the different coding levels of the ICD-11 might improve discrimination of CPSP from other chronic pain conditions not induced by surgery. Although neuropathic CPSP increases pain severity and requires alternative therapeutic approaches to nociceptive pain, a specific code to differentiate between neuropathic and non-neuropathic CPSP is not available. For clinical practice and research, the evidence-based ICD-11 definition, which provides clear-cut diagnostic criteria, should generally be used instead of pain scores alone. This will improve the comparability of data, form the basis for future diagnostic and therapeutic approaches, and facilitate communication.

Factors associated with poor pain experience after surgery

OBJECTIVE

To identify factors associated with poor postoperative pain experience by examining patient-related and procedural variables.

METHODS

An exploratory secondary analysis was conducted on data from 971 adult patients undergoing elective surgery under general anesthesia across five French teaching hospitals. Preoperative anxiety was assessed using the Amsterdam Preoperative Anxiety and Information Scale (APAIS). Pain, sleep quality and well-being were measured preoperatively and postoperatively using visual analog scales (VAS). The primary endpoint was the patient experience measured by the Evaluation du Vécu de l'Anesthésie Generale (EVAN-G) questionnaire on postoperative day 1, with poor pain experience defined as a score below the 25th percentile on the EVAN-G pain dimension. Univariate and multivariate logistic regression analyses were performed to identify factors associated with poor pain experience.

RESULTS

Poor pain experience was reported by 271 patients (27.9%). Multivariate analysis identified intraoperative use of remifentanil and sufentanil as an independent predictor of poor pain experience with an OR of 26.96 (95% CI 2.17 to 334.23, p=0.01). Additionally, age (OR 0.97, p=0.003), absence of premedication (OR 0.49, p=0.035) and orthopedic surgery (OR 0.29, p=0.005) were associated with a lower likelihood of poor pain experience. Conversely, American Society of Anesthesiologists (ASA) 3 status (OR 5.09, p=0.028), postoperative anxiolytic use (OR 8.20, p<0.001), amnesia (OR 1.58, p=0.001), higher VAS pain (p<0.001) and lower well-being scores (p=0.007) on day 1 were predictors of poor pain experience.

CONCLUSION

The intraoperative use of remifentanil and sufentanil is independently associated with poorer postoperative pain experience. These findings highlight the need to reassess intraoperative analgesic strategies to enhance patient outcomes and reduce postoperative complications.

Chronic postsurgical pain and transitional pain services: a narrative review highlighting European perspectives

BACKGROUND/IMPORTANCE

Chronic postsurgical pain (CPSP) is a significant, often debilitating outcome of surgery, impacting patients' quality of life and placing a substantial burden on healthcare systems worldwide. CPSP (pain persisting for more than 3 months postsurgery) leads to both physical and psychological distress. Recognized as a distinct chronic pain entity in International Classification of Diseases, 11th Revision, CPSP enables better reporting and improved management strategies. Despite advancements in surgical care, CPSP remains prevalent, affecting 5%-85% of patients, with higher rates following thoracotomies, amputations, mastectomies and joint replacements.

OBJECTIVE

The acute to chronic pain transition involves complex interactions between peripheral and central mechanisms, with central sensitization playing a key role. Identifying high-risk patients is crucial for prevention, with factors such as surgical type, nerve injury, neuropathic elements in acute postoperative pain, and psychosocial conditions being significant contributors.

EVIDENCE REVIEW

Current pain management strategies, including multimodal therapy and regional anesthesia, show limited effectiveness in preventing CPSP. Neuromodulation interventions, though promising, are not yet established as preventive modalities.

FINDINGS

Transitional pain services (TPSs) offer a comprehensive, multidisciplinary approach to managing CPSP and reducing opioid dependence, addressing both physical and psychosocial aspects of functional recovery. While promising results have been seen in Canada and Finland, TPSs are not yet widely implemented in Europe. There is also growing interest in pain biomarkers, through initiatives such as the A2CPS program, aiming to improve CPSP prediction and develop targeted interventions.

CONCLUSIONS

Future research should focus on large-scale studies integrating various factors to facilitate CPSP prediction, refine prevention strategies and reduce its long-term impact.

Comparison of Spinal Cord Stimulation, Dorsal Root Ganglion Stimulation, and Association of Both in Patients With Refractory Chronic Back and/or Lower Limb Neuropathic Pain: A Prospective, Randomized, Double-Blind, Cross-Over Trial (BOOST-DRG Study)

OBJECTIVES

Spinal cord stimulation (SCS) and dorsal root ganglion stimulation (DRGS) have individually shown efficacy in relieving pain in patients with persistent spinal pain syndrome after spinal surgery (PSPS-T2). Combining SCS and DRGS simultaneously, along with Burst stimulation programming, may enhance the responder rate of patients with PSPS-T2.

MATERIAL AND METHODS

This study aimed to compare the pain relief (≥50%) responder rates in SCS, DRGS, and SCS+DGRS (DUAL) through a three-month randomized cross-over trial in patients with PSPS-T2. After the cross-over period, stimulation programming was switched to Burst. Secondary objectives included evaluating the clinical efficacy at three-, four-, six-, and 12-month follow-ups, assessing pain intensity, area of pain, area of paresthesia coverage, quality of life, functional disability, psychologic distress, medication intake, and the Multidimensional Clinical Response Index (MCRI).

RESULTS

The responder rate of pain relief was similar in SCS, DRGS, and DUAL (60%, p = 0.84) at the end of the cross-over period, increasing to 80% with the ability to switch between stimulation possibilities. Burst programming did not provide additional pain relief at the four-month follow-up (p = 0.99). Clinical outcomes significantly improved until 12-month follow-up compared with baseline. Considering a clinically significant increase of 1.05 of the MCRI, all patients were responders at three-, four-, and six- month follow-up, and 80% were responders at 12 months compared with baseline.

CONCLUSIONS

The full option to stimulate different neural structures, separately or simultaneously, led to improved responder rates, allowing patients to personalize treatment. A multidimensional assessment is essential to reveal the full potential benefits of neuromodulation in patients with chronic pain.

Presurgical anxiety and acute postsurgical pain predict worse chronic pain profiles after total knee/hip arthroplasty

INTRODUCTION

Total joint arthroplasties generally achieve good outcomes, but chronic pain and disability are a significant burden after these interventions. Acknowledging relevant risk factors can inform preventive strategies. This study aimed to identify chronic pain profiles 6 months after arthroplasty using the ICD-11 (International Classification of Diseases) classification and to find pre and postsurgical predictors of these profiles.

MATERIALS AND METHODS

Patients undergoing total knee/hip arthroplasty (n = 209, female = 54.5%) were assessed before surgery, 48 h and 6 months postsurgery for sociodemographic, pain-related, disability and psychological characteristics. K-means-constrained cluster analysis identified chronic pain profiles based on 6-month pain intensity, pain interference and disability. Chi-square tests or one-way ANOVA explored between-cluster differences. Multinomial regression identified predictors of cluster membership. Separate models analyzed presurgical (model 1), postsurgical (model 2) and a combination of previously significant pre and postsurgical (model 3) variables.

RESULTS

A three-cluster solution was selected, translating increasingly worse chronic pain severity: cluster 1 (C1, n = 129), cluster 2 (C2, n = 60) and cluster 3 (C3, n = 20). There were presurgical differences among clusters in the presence of other painful sites (p = 0.013, ϕc = 0.20), pain interference (p = 0.038, η2 = 0.031), disability (p = 0.020, η2 = 0.037), pain catastrophizing (p = 0.019, η2 = 0.060), anxiety (p < 0.001, η2 = 0.087), depression (p = 0.017; η2 = 0.039), self-efficacy (p = 0.018, η2 = 0.038) and satisfaction with life (p = 0.034, η2 = 0.032), postsurgical pain frequency (p = 0.003, ϕc = 0.243) and intensity (p < 0.001, η2 = 0.101). In model 1, disability predicted C2 (OR = 1.040) and anxiety predicted C3 (OR = 1.154) membership. In model 2, pain intensity predicted C3 (OR = 1.690) membership. In model 3, presurgical anxiety predicted C3 (OR = 1.181) and postsurgical pain intensity predicted C2 (OR = 1.234) and C3 (OR = 1.679) membership.

CONCLUSIONS

Most patients had low chronic pain severity at 6 months, but a relevant percentage exhibited poor outcomes. Membership to different outcome profiles was predicted by presurgical anxiety and acute postsurgical pain. These seem promising targets to prevent pain chronification that should be optimized for better surgical outcomes.

Personalized outcomes in neuropathic pain: a clinical relevance and assay sensitivity analysis from a randomized controlled trial

OBJECTIVE

To explore the clinical relevance and assay sensitivity of using personalized outcomes using data from a randomized clinical trial (RCT) in people with chemotherapy-induced peripheral neuropathy (CIPN).

DESIGN

This study is a secondary analysis that leveraged data from a RCT of transcutaneous electrical stimulation for CIPN to test whether personalized outcomes could minimize potential floor effects and increase the assay sensitivity of pain clinical trials (ie, ability to detect a true treatment effect).

SETTING

Participants were recruited for a RCT from community oncology clinics in the United States.

PARTICIPANTS

Adults with CIPN (N = 72) who reported on average ≥4 intensity (measured via a 7-day baseline diary) for at least 1 of the following pain qualities: hot/burning pain, sharp/shooting pain, and/or cramping.

METHODS

Personalized outcomes were defined based on participants' unique presentation of pain qualities at baseline, measured via 0-10 numeric rating scales (NRS), or ranking of the distress caused by the pain qualities. Analysis of covariance models estimated the treatment effect as measured by personalized and non-personalized outcomes.

RESULTS

The adjusted mean difference between groups was higher using personalized outcomes (ie, 1.21-1.25 NRS points) compared to a non-personalized outcome (ie, 0.97 NRS points), although the standardized effect sizes were similar between outcomes (0.49-0.54).

CONCLUSIONS

These results suggest that personalized pain quality outcomes could minimize floor effects, while providing similar assay sensitivity to non-personalized pain quality outcomes. Personalized outcomes better reflect an individual's unique experience, inherently providing more clinically relevant estimates of treatment effects. Personalized outcomes may be advantageous, particularly for clinical trials in populations with high inter-individual variability in pain qualities.

From pain level to pain experience: redefining acute pain assessment to enhance understanding of chronic postsurgical pain

BACKGROUND

Chronic postsurgical pain (CPSP) significantly impairs quality of life and poses a substantial healthcare burden, affecting up to a quarter of patients undergoing surgery. Although acute pain is recognised as a predictor for CPSP development, the role of patient experience remains underexplored. This study examines the predictive value of patient experience alongside traditional risk factors for CPSP after orthopaedic surgery.

METHODS

An exploratory analysis was conducted on 294 patients from a multicentre randomised clinical trial comparing continuous perineural analgesia and single-injection nerve block in ambulatory orthopaedic surgeries. Patient experience was assessed using the Evaluation du Vecu de l'Anesthésie Générale (EVAN-G) validated questionnaire. Factors associated with CPSP at 90 days after surgery were identified through univariate and multivariate analyses, incorporating patient-reported outcomes and classical variables.

RESULTS

Out of 219 patients with complete data, 63 (29%) developed CPSP at day 90. Multivariate analysis revealed a poor pain experience, as assessed by the pain dimension of EVAN-G on postoperative day 2, as an independent predictor of CPSP (odds ratio 6.45, 95% confidence interval 1.65-25.26, P<0.01). Poor pain experience was associated with an augmented risk of CPSP.

CONCLUSIONS

This study underscores the role of patient-reported outcomes, specifically the pain experience dimension captured by the EVAN-G scale, in prediction of CPSP 90 days after surgery. It suggests a shift from conventional assessments of pain intensity to a comprehensive understanding of pain experience, advocating for tailored pain management approaches that could reduce chronic pain, thereby improving patient quality of life and functional recovery.

Current concepts and targets for preventing the transition of acute to chronic postsurgical pain

PURPOSE OF REVIEW

It is estimated that approximately a third of patients undergoing certain surgeries may report some degree of persistent pain postoperatively. Chronic postsurgical pain (CPSP) reduces quality of life, is challenging to treat, and has significant socio-economic impact.

RECENT FINDINGS

From an epidemiological perspective, factors that predispose patients to the development of CPSP may be considered in relation to the patient, the procedure or, the care environment. Prevention or management of transition from acute to chronic pain often need a multidisciplinary approach beginning early in the preoperative period and continuing beyond surgical admission. The current concepts regarding the role of central and peripheral nervous systems in chronification of pain may provide targets for future therapies but, the current evidence seems to suggest that a multimodal analgesic approach of preventive analgesia along with a continued follow-up and treatment after hospital discharge may hold the key to identify and manage the transitioning of acute to chronic pain.

SUMMARY

A comprehensive multidisciplinary approach with prior identification of risk factors, minimizing the surgical insult and a culture of utilizing multimodal analgesia and continued surveillance beyond the period of hospitalization is an important step towards reducing the development of chronic pain. A transitional pain service model may accomplish many of these goals.

Perioperative Dexamethasone in Diabetic Patients: A Systematic Review and Meta-Analysis of Randomized, Placebo-Controlled Trials

BACKGROUND

The perioperative use of dexamethasone in diabetic patients remains controversial due to concerns related to infection and adverse events. This study aimed to determine whether clinical evidence supports withholding dexamethasone in diabetic patients due to concern for infection risk. We hypothesized that there is no difference in infectious outcomes between dexamethasone-treated patients and controls.

METHODS

A literature search was performed on November 22, 2022 to identify randomized, placebo-controlled trials investigating short-course (<72 hours), perioperative dexamethasone that explicitly included diabetic patients and measured at least 1 clinical outcome. Pertinent studies were independently searched in PubMed, Embase, and Cochrane. Authors for all identified studies were contacted with the aim of performing quantitative subgroup analyses of diabetic patients. The primary end point was surgical site infection and the secondary end point was a composite of adverse events. Qualitative remarks were reported based on the total available data and a quality assessment tool. Meta-analyses were performed using inverse variance with random effects. Heterogeneity was assessed via standard χ2 and I2 tests.

RESULTS

Sixteen unique studies were included, 5 of which were analyzed quantitatively. Of the 2592 diabetic patients, 2344 (1184 randomized to dexamethasone and 1160 to placebo) were analyzed in at least 1 quantitative outcome. Quantitative analysis showed that the use of perioperative dexamethasone had no effect on the risk of surgical site infections (log odds ratio [LOR], -0.10, 95%; 95% confidence interval [CI], -0.64 to 0.44) while significantly reducing the risk of composite adverse events (LOR, -0.33; 95% CI, -0.62 to -0.05). Qualitative analysis reinforced these findings, demonstrating noninferior to superior results across all clinical outcomes. There was high heterogeneity between the included studies.

CONCLUSIONS

Current evidence suggests perioperative dexamethasone may be given to diabetic patients without increasing the risk of infectious complications. Prospective investigations aimed at optimizing dose, frequency, and timing are needed, as well as studies aimed explicitly at exploring the use of dexamethasone in patients with poorly controlled diabetes.

Understanding Kinesiophobia: Predictors and Influence on Early Functional Outcomes in Patients with Total Knee Arthroplasty

This observational study aimed to identify predictors of kinesiophobia and examine its correlation with early functional outcomes in TKA recipients. On the first and fifth postoperative days (POD1 and POD5), we evaluated pain using the International Pain Outcomes Questionnaire (IPO-Q) and created multidimensional pain composite scores (PCSs). The Total Pain Composite Score (PCStotal) assesses the overall impact of pain, taking into account outcomes of pain intensity, pain-related interference with function, and emotions and side effects. Functional status on POD 5 was determined by the Barthel index, 6 min walking test, and knee range of motion. Kinesiophobia was assessed on POD5 using the Tampa Scale for Kinesiophobia (TSK). Among 75 TKA patients, 27% exhibited kinesiophobia. The final regression model highlighted PCStotal on POD5 (OR = 6.2, CI = 1.9-19.9), PCStotal (OR = 2.1, CI = 1.2-3.8) on POD1, and the intensity of chronic pain before surgery (OR = 1.4, CI = 1.1-2.1) as significant kinesiophobia predictors. On POD5, those with kinesiophobia showed increased dependency, slower gait, and poorer knee extension recovery. This study emphasizes the need to identify and address kinesiophobia in TKA patients for better functional outcomes and recovery. Additionally, it is vital to assess different domains of pain, not just pain intensity, as it can lead to kinesiophobia development.

Evaluating the balance of benefits and harms in chronic pain clinical trials: prioritizing individual participants over individual outcomes

BACKGROUND

Randomized clinical trials (RCTs) generally assess efficacy and safety separately, with the conclusion of whether a treatment is beneficial based solely on the efficacy endpoint. However, assessing and combining efficacy and safety domains, using a single composite outcome measure, can provide a more comprehensive assessment of the overall effect of a treatment. Furthermore, composite outcomes can incorporate information regarding the relationship between the individual outcomes. In fact, such outcomes have been suggested in the clinical trials literature for at least 15 years.

OBJECTIVES

To (1) identify whether recent primary publications of chronic pain RCTs from major pain journals included a composite outcome measure of benefits and harms and (2) discuss the potential benefits of such outcomes in various stages of treatment development, including as outcome measures in RCTs, and to support decisions of Data and Safety Monitoring Boards and ordering of treatments in the context of treatment guidelines.

EVIDENCE REVIEW

RCTs published in 6 major pain journals published between 2016 and 2021 that investigated interventions for chronic pain were reviewed.

FINDINGS

Of 73 RCTs identified, only 2 included a composite outcome measure of benefits and harms. Both of these articles compared 2 active treatments.

CONCLUSIONS

Composite outcomes of benefits and harms are underutilized in chronic pain RCTs. The advantages and challenges of using such outcomes are discussed.

Group-Based Integrative Pain Management in Primary Care: A Study Protocol for Multilevel Interventions to Address Health Disparities

Background

Socioeconomically disadvantaged populations have a high prevalence of chronic pain, exacerbated by social isolation, intersectional stigma, and disparities in pain assessment and treatment. Effective interventions using a multilevel, biopsychosocial approach are needed to decrease the unequal burden of pain. Group-based integrative pain management in primary care safety net clinics is a promising model to improve pain care for racially and ethnically diverse low-income people.

Objective

To describe a study protocol to test the impacts of 2 group-based models - group acupuncture and integrative group medical visits - on multilevel pain-related outcomes.

Methods

The study uses a 2x2 factorial randomized clinical trial to test two 12 week group-based models: group acupuncture and integrative group medical visits (IGMV, with psychoeducation, mind-body approaches, and social support). English or Spanish-speaking adults with chronic pain for ≥3 months receiving care in San Francisco Department of Public Health primary care clinics are eligible for the trial. All participants will receive usual care and be randomized to group acupuncture, IGMV, both, or waitlist control. The primary outcomes are changes from baseline to 3 month follow-up in pain impact and in social support for chronic pain. Secondary outcomes include pain interference, pain intensity, depression, anxiety, quality of life, and social isolation. Data will include patient-reported outcomes, electronic health record data, and qualitative interviews, focus groups and observations to assess multilevel individual, interpersonal and organizational outcomes.

Discussion

Multilevel approaches are needed to advance health equity in pain management. Our study contributes to knowledge of group-based integrative pain management in primary care safety net clinics to address multilevel barriers and disparities in pain care.

Opinions of Health Care Providers About Neuromodulation for Pain: Results of an Online Survey at the 2nd Joint Congress of the International Neuromodulation Society European Chapters

INTRODUCTION

Neuromodulation for pain has been successfully applied for decades, in that the goals and expectations that patients aim to achieve are clearly described. Nevertheless, the point of view of health care providers is less clear. Therefore, this study aimed to explore the goals, expectations, and definition of success for neuromodulation for pain according to health care providers.

MATERIALS AND METHODS

An online survey was developed and spread at the 2nd Joint Congress of the International Neuromodulation Society (INS) European Chapters in September 2021 in Paris. Respondents were asked 1) to select the goals to treat patients with neuromodulation for pain, 2) to indicate factors that they expect to change according to neuromodulation for pain, and 3) to provide their definition of success of neuromodulation for pain.

RESULTS

We approached 101 respondents, of whom 88 health care providers at least partly completed the survey. Increasing mobility/functionality (26.7%), decreasing pain intensity (24.5%), and decreasing medication use (16.6%) were the most frequently reported goals of neuromodulation. The same top three variables were selected as factors that health care providers expected to change. For the definition of success, quality of life of patients outranked other definitions. Other highly ranked definitions, in descending order, were obtaining pain relief, increasing functionality, and increasing patient satisfaction.

DISCUSSION

Goals and expectations of health care providers are not completely in line with previously explored goals of patients that are related to pain relief and improving walking abilities. Health care providers seem to put a high emphasis on the quality of life of the patient when evaluating the success of neuromodulation, which is not completely aligned with the currently used reimbursement rules that are mainly focusing on pain relief instead of incorporating health-related quality of life.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT05013840.

Should we Oppose or Combine Waveforms for Spinal Cord Stimulation in PSPS-T2 Patients? A Prospective Randomized Crossover Trial (MULTIWAVE Study)

Refractory persistent spinal pain syndrome after surgery (PSPS-T2) can be successfully addressed by spinal cord stimulation (SCS). While conventional stimulation generates paresthesia, recent systems enable the delivery of paresthesia-free stimulation. Studies have claimed non-inferiority/superiority of selected paresthesia-free stimulation compared with paresthesia-based stimulation, but the comparative efficacy between different waveforms still needs to be determined in a given patient. We designed a randomized controlled 3-month crossover trial to compare pain relief of paresthesia-based stimulation versus high frequency versus burst in 28 PSPS-T2 patients implanted with multiwave SCS systems. Our secondary objectives were to determine the efficacy of these 3 waveforms on pain surface, quality of life, functional capacity, psychological distress, and validated composite multidimensional clinical response index to provide holistic comparisons at 3-, 6-, 9-, and 15-month post-randomization. The preferred stimulation modality was documented during the follow-up periods. No difference between the waveforms was observed in this study (P = .08). SCS led to significant pain relief, quality of life improvement, improvement of multidimensional clinical response index, and of all other clinical outcomes at all follow-up visits. Forty-four percent of the patients chose to keep the paresthesia-based stimulation modality after the 15-month follow-up period. By giving the possibility to switch and/or to combine several waveforms, the overall rate of SCS responders further increased with 25%. In this study, high frequency or burst do not appear superior to paresthesia-based stimulation, wherefore paresthesia-based stimulation should still be considered as a valid option. However, combining paresthesia-based stimulation with paresthesia-free stimulation, through personalized multiwave therapy, might significantly improve SCS responses. PERSPECTIVE: This article assesses clinical SCS efficacy on pain relief, by comparing paresthesia-based stimulation and paresthesia-free stimulation (including high frequency and burst) modalities in patient presenting with PSPS-T2. Switching and/or combining waveforms contribute to increasing the global SCS responders rate.

The Perioperative Pain Management Bundle is Feasible: Findings From the PAIN OUT Registry

OBJECTIVES

The quality of postoperative pain management is often poor. A "bundle," a small set of evidence-based interventions, is associated with improved outcomes in different settings. We assessed whether staff caring for surgical patients could implement a "Perioperative Pain Management Bundle" and whether this would be associated with improved multidimensional pain-related patient-reported outcomes (PROs).

METHODS

"PAIN OUT," a perioperative pain registry, offers tools for auditing pain-related PROs and obtaining information about perioperative pain management during the first 24 hours after surgery. Staff from 10 hospitals in Serbia used this methodology to collect data at baseline. They then implemented the "Perioperative Pain Management Bundle" into the clinical routine and collected another round of data. The bundle consists of 4 treatment elements: (1) a full daily dose of 1 to 2 nonopioid analgesics (eg, paracetamol and/or nonsteroidal anti-inflammatory drugs), (2) at least 1 type of local/regional anesthesia, (3) pain assessment by staff, and (4) offering patients information about pain management. The primary endpoint was a multidimensional pain composite score (PCS), evaluating pain intensity, interference, and side effects that was compared between patients who received the full bundle versus not.

RESULTS

Implementation of the complete bundle was associated with a significant reduction in the PCS ( P < 0.001, small-medium effect size [ES]). When each treatment element was evaluated independently, nonopioid analgesics were associated with a higher PCS (ie, poorer outcome, and negligible ES), and the other elements were associated with a lower PCS (all negligible small ES). Individual PROs were consistently better in patients receiving the full bundle compared with 0 to 3 elements. The PCS was not associated with the surgical discipline.

DISCUSSION

We report findings from using a bundle approach for perioperative pain management in patients undergoing mixed surgical procedures. Future work will seek strategies to improve the effect.

Treatment of Refractory Low Back Pain Using Passive Recharge Burst in Patients Without Options for Corrective Surgery: Findings and Results From the DISTINCT Study, a Prospective Randomized Multicenter Controlled Trial

OBJECTIVE

Spinal cord stimulation (SCS) is effective for relieving chronic intractable pain conditions. The Dorsal spInal cord STImulatioN vs mediCal management for the Treatment of low back pain study evaluates the effectiveness of SCS compared with conventional medical management (CMM) in the treatment of chronic low back pain in patients who had not undergone and were not candidates for lumbar spine surgery.

METHODS AND MATERIALS

Patients were randomized to passive recharge burst therapy (n = 162) or CMM (n = 107). They reported severe pain and disability for more than a decade and had failed a multitude of therapies. Common diagnoses included degenerative disc disease, spondylosis, stenosis, and scoliosis-yet not to a degree amenable to surgery. The six-month primary end point compared responder rates, defined by a 50% reduction in pain. Hierarchical analyses of seven secondary end points were performed in the following order: composite responder rate (numerical rating scale [NRS] or Oswestry Disability Index [ODI]), NRS, ODI, Pain Catastrophizing Scale responder rate, Patient Global Impression of Change (PGIC) responder rate, and Patient-Reported Outcome Measure Information System-29 in pain interference and physical function.

RESULTS

Intention-to-treat analysis showed a significant difference in pain responders on NRS between SCS (72.6%) and CMM (7.1%) arms (p < 0.0001). Of note, 85.2% of those who received six months of therapy responded on NRS compared with 6.2% of those with CMM (p < 0.0001). All secondary end points indicated the superiority of burst therapy over CMM. A composite measure on function or pain relief showed 91% of subjects with SCS improved, compared with 16% of subjects with CMM. A substantial improvement of 30 points was observed on ODI compared with a

CONCLUSIONS

This study found substantial improvement at six months in back pain, back pain-related disability, pain-related emotional suffering, PGIC, pain interference, and physical function in a population with severe, debilitating back pain for more than a decade. These improvements were reported in conjunction with reduced opioid use, injection, and ablation therapy.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT04479787.

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Key Words

• composite outcomes
• persistent spinal pain syndrome
• refractory chronic low back pain
• spinal cord stimulation

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MESH Headings

• Humans
• Low Back Pain/therapy
• Low Back Pain/psychology
• Treatment Outcome
• Prospective Studies
• Back Pain
• Spinal Cord Stimulation/methods
• Chronic Pain/diagnosis
• Chronic Pain/therapy

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Grants

• K08 CA228039 NCI NIH HHS

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Affiliation(s)

Timothy Deer The Spine and Nerve Center of the Virginias, Charleston, WV, USA
Christopher Gilligan Brigham & Women's Hospital, Boston, MA, USA
Steven Falowski Center for Interventional Pain & Spine, Lancaster, PA, USA
Mehul Desai International Spine, Pain & Performance Center, Washington, DC, USA
Julie Pilitsis Florida Atlantic University, FL, USA
Jessica Jameson Axis Spine Center, ID, USA
Susan Moeschler Mayo Clinic, Rochester, NY, USA
Robert Heros Spinal Diagnostics, OR, USA
Edward Tavel Clinical Trials of South Carolina, Charleston, SC, USA
Anne Christopher Saint Louis Pain Consultants, Chesterfield, MO, USA
Denis Patterson Nevada Advanced Pain Specialists, Reno, NV, USA
Sayed Wahezi Montefiore Medical Center-Waters Place, New York, NY, USA
Jacqueline Weisbein Napa Valley Orthopedic Medical Group, Napa, CA, USA
Ajay Antony The Orthopaedic Institute, FL, USA
Robert Funk Indiana Spine Group, IN, USA
Mohab Ibrahim Banner University Medical Center Tucson Campus, Tucson, AZ, USA
Chi Lim Carolina Orthopaedic & Neurosurgical Associates, SC, USA
Derron Wilson Goodman Campbell Brain & Spine, IN, USA
Michael Fishell Advanced Pain Care, NV, USA
Keith Scarfo Rhode Island Hospital, Providence, RI, USA
David Dickerson Northshore University HealthSystem, Chicago, IL, USA
Edward Braun Kansas University Medical Center, KS, USA
Patrick Buchanan Spanish Hills Interventional Pain Specialists, Camarillo, CA, USA
Robert M Levy Anesthesia Pain Care Consultants-Tamarac
Nathan Miller Coastal Pain & Spinal Diagnostics Medical Group, Carlsbad, CA, USA
Jonathan Duncan Burkhart Research Institute for Orthopaedics, San Antonio, TX, USA
Jijun Xu The Cleveland Clinic Foundation, OH, USA
Kenneth Candido Chicago Anesthesia Associates, SC, Chicago, IL, USA
Scott Kreiner Barrow Brain & Spine-Ahwatukee, Phoenix, AZ, USA
Marie E Fahey Abbott Labs, Austin, TX, USA
James Yue Connecticut Orthopaedics, CT, USA

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Cost-effectiveness of the Perioperative Pain Management Bundle a registry-based study

Introduction

The Perioperative Pain Management Bundle was introduced in 10 Serbian PAIN OUT network hospitals to improve the quality of postoperative pain management. The Bundle consists of 4 elements: informing patients about postoperative pain treatment options; administering a full daily dose of 1-2 non-opioid analgesics; administering regional blocks and/or surgical wound infiltration; and assessing pain after surgery. In this study, we aimed to assess the cost-effectiveness of the Bundle during the initial 24 h after surgery.

Materials and methods

The assessment of cost-effectiveness was carried out by comparing patients before and after Bundle implementation and by comparing patients who received all Bundle elements to those with no Bundle element. Costs of postoperative pain management included costs of the analgesic medications, costs of labor for administering these medications, and related disposable materials. A multidimensional Pain Composite Score (PCS), the effectiveness measurement, was obtained by averaging variables from the International Pain Outcomes questionnaire evaluating pain intensity, interference of pain with activities and emotions, and side effects of analgesic medications. The incremental cost-effectiveness ratio (ICER) was calculated as the incremental change in costs divided by the incremental change in PCS and plotted on the cost-effectiveness plane along with the economic preference analysis.

Results

The ICER value calculated when comparing patients before and after Bundle implementation was 181.89 RSD (1.55 EUR) with plotted ICERs located in the northeast and southeast quadrants of the cost-effectiveness plane. However, when comparing patients with no Bundle elements and those with all four Bundle elements, the calculated ICER was -800.63 RSD (-6.82 EUR) with plotted ICERs located in the southeast quadrant of the cost-effectiveness plane. ICER values differ across surgical disciplines.

Conclusion

The proposed perioperative pain management Bundle is cost-effective. The cost-effectiveness varies depending on the number of implemented Bundle elements and fluctuates across surgical disciplines.

Core patient-reported outcome measures for chronic pain patients treated with spinal cord stimulation or dorsal root ganglia stimulation

BACKGROUND

Neurostimulation is a highly effective therapy for the treatment of chronic Intractable pain, however, due to the complexity of pain, measuring a subject's long-term response to the therapy remains difficult. Frequent measurement of patient-reported outcomes (PROs) to reflect multiple aspects of subjects' pain is a crucial step in determining therapy outcomes. However, collecting full-length PROs is burdensome for both patients and clinicians. The objective of this work is to identify the reduced set of questions from multiple validated PROs that can accurately characterize chronic pain patients' responses to neurostimulation therapies.

METHODS

Validated PROs were used to capture pain, physical function and disability, as well as psychometric, satisfaction, and global health metrics. PROs were collected from 509 patients implanted with Spinal Cord Stimulation (SCS) or Dorsal Root Ganglia (DRG) neurostimulators enrolled in the prospective, international, post-market REALITY study (NCT03876054, Registration Date: March 15, 2019). A combination of linear regression, Pearson's correlation, and factor analysis were used to eliminate highly correlated questions and find the minimal meaningful set of questions within the predefined domains of each scale.

RESULTS

The shortened versions of the questionnaires presented almost identical accuracy for classifying the therapy outcomes as compared to the validated full-length versions. In addition, principal component analysis was performed on all the PROs and showed a robust clustering of pain intensity, psychological factors, physical function, and sleep across multiple PROs. A selected set of questions captured from multiple PROs can provide adequate information for measuring neurostimulation therapy outcomes.

CONCLUSIONS

PROs are important subjective measures to evaluate the physiological and psychological aspects of pain. However, these measures are cumbersome to collect. These shorter and more targeted PROs could result in better patient engagement, and enhanced and more frequent data collection processes for digital health platforms that minimize patient burden while increasing therapeutic benefits for chronic pain patients.

Using Daily Ratings to Examine Treatment Dose and Response in Cognitive Behavioral Therapy for Chronic Pain: A Secondary Analysis of the Co-Operative Pain Education and Self-Management Clinical Trial

BACKGROUND

Cognitive behavioral therapy for chronic pain (CBT-CP) has a strong evidence base, but little is known about when treatment benefits are achieved. The present study is a secondary analysis of individuals with chronic back pain recruited for a noninferiority trial comparing interactive voice response (IVR) CBT-CP with in-person CBT-CP.

METHODS

On the basis of data from daily IVR surveys, a clinically meaningful change was defined as a 30% reduction in pain intensity (n = 108) or a 45% increase in daily steps (n = 104) compared with the baseline week. We identified individuals who achieved a meaningful change at any point during treatment, and then we compared those who maintained a meaningful change in their final treatment week (i.e., responders) with those who did not or who achieved a meaningful change but lapsed (i.e., nonresponders).

RESULTS

During treatment, 46% of participants achieved a clinically meaningful decrease in pain intensity, and 66% achieved a clinically significant increase in number of steps per day. A total of 54% of patients were classified as responders in terms of decreases in pain intensity, and 70% were responders in terms of increases in step count. Survival analyses found that 50% of responders first achieved a clinically meaningful change by week 4 for pain intensity and week 2 for daily steps. Dropout and demographic variables were unrelated to responder status, and there was low agreement between the two measures of treatment response.

CONCLUSIONS

Collectively, results suggest that most responders improve within 4 weeks. Evaluating treatment response is highly specific to the outcome measure, with little correlation across outcomes.

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.

Objective wearable measures and subjective questionnaires for predicting response to neurostimulation in people with chronic pain

BACKGROUND

Neurostimulation is an effective therapy for treating and management of refractory chronic pain. However, the complex nature of pain and infrequent in-clinic visits, determining subject's long-term response to the therapy remains difficult. Frequent measurement of pain in this population can help with early diagnosis, disease progression monitoring, and evaluating long-term therapeutic efficacy. This paper compares the utilization of the common subjective patient-reported outcomes with objective measures captured through a wearable device for predicting the response to neurostimulation therapy.

METHOD

Data is from the ongoing international prospective post-market REALITY clinical study, which collects long-term patient-reported outcomes from 557 subjects implanted by Spinal Cord Stimulator (SCS) or Dorsal Root Ganglia (DRG) neurostimulators. The REALITY sub-study was designed for collecting additional wearables data on a subset of 20 participants implanted with SCS devices for up to six months post implantation. We first implemented a combination of dimensionality reduction algorithms and correlation analyses to explore the mathematical relationships between objective wearable data and subjective patient-reported outcomes. We then developed machine learning models to predict therapy outcome based on the subject's response to the numerical rating scale (NRS) or patient global impression of change (PGIC).

RESULTS

Principal component analysis showed that psychological aspects of pain were associated with heart rate variability, while movement-related measures were strongly associated with patient-reported outcomes related to physical function and social role participation. Our machine learning models using objective wearable data predicted PGIC and NRS outcomes with high accuracy without subjective data. The prediction accuracy was higher for PGIC compared with the NRS using subjective-only measures primarily driven by the patient satisfaction feature. Similarly, the PGIC questions reflect an overall change since the study onset and could be a better predictor of long-term neurostimulation therapy outcome.

CONCLUSIONS

The significance of this study is to introduce a novel use of wearable data collected from a subset of patients to capture multi-dimensional aspects of pain and compare the prediction power with the subjective data from a larger data set. The discovery of pain digital biomarkers could result in a better understanding of the patient's response to therapy and their general well-being.

Cannabinoid Therapy: Attitudes and Experiences of People With Chronic Pain

OBJECTIVE

Clinical trials of cannabinoids for chronic pain have mixed and often inconclusive results. In contrast, many prospective observational studies show the analgesic effects of cannabinoids. This survey study aimed to examine the experiences/attitudes of individuals with chronic pain who are currently taking, have previously taken, or never taken cannabinoids for chronic pain to inform future research.

METHODS

This study is based on a cross-sectional, web-based survey of individuals with self-reported chronic pain. Participants were invited to participate through an email that was distributed to the listservs of patient advocacy groups and foundations that engage individuals with chronic pain.

RESULTS

Of the 969 respondents, 444 (46%) respondents reported currently taking, 213 (22%) previously taken, and 312 (32%) never taken cannabinoids for pain. Participants reported using cannabinoids to treat a wide variety of chronic pain conditions. Those currently taking cannabinoids (vs previously) more frequently reported: (1) large improvements from cannabinoids in all pain types, including particularly difficult-to-treat chronic overlapping pain conditions (eg, pelvic pain), (2) improvements in comorbid symptoms (eg, sleep), and (3) lower interference from side effects. Those currently taking cannabinoids reported more frequent and satisfactory communication with clinicians regarding cannabinoid use. Those never taken cannabinoids reported a lack of suggestion/approval of a clinician (40%), illegality (25%), and lack of FDA regulation (19%) as reasons for never trying cannabinoids.

CONCLUSION

These findings underscore the importance of conducting high-quality clinical trials that include diverse pain populations and clinically relevant outcomes that if successful, could support FDA approval of cannabinoid products. Clinicians could then prescribe and monitor these treatments similarly to other chronic pain medications.

Proportion of clinical holistic responders in patients with persistent spinal pain syndrome type II treated by subthreshold spinal cord stimulation compared to best medical treatment: a study protocol for a multicentric randomised controlled trial (TRADITION)

BACKGROUND

Integrating information on bodily functions, pain intensity and quality of life into one composite measure of a holistic responder has recently been proposed as a useful method to evaluate treatment efficacy of spinal cord stimulation (SCS) in patients with therapy-refractory persistent spinal pain syndrome type II (PSPS-T2). Previous studies already demonstrated the efficacy of standard SCS over best medical treatment (BMT) and the superiority of new subthreshold (i.e. paresthesia free) SCS paradigms compared to standard SCS. Nevertheless, the efficacy of subthreshold SCS compared to BMT has not yet been investigated in patients with PSPS-T2, neither with unidimensional outcomes nor with a composite measure. The current objective is to examine whether subthreshold SCS, compared to BMT, provided to patients with PSPS-T2 results in a different proportion of clinical holistic responders (as composite measure) at 6 months.

METHODS

A two-arm multicentre randomised controlled trial will be conducted whereby 114 patients will be randomised (1:1) to (a) BMT or (b) paresthesia-free SCS. After a follow-up period of 6 months (primary time endpoint), patients receive the opportunity to cross over towards the other treatment group. The primary outcome is the proportion of clinical holistic responders at 6 months (i.e. a composite measure of pain intensity, medication, disability, health-related quality of life and patient satisfaction). The secondary outcomes are work status, self-management, anxiety, depression and healthcare expenditure.

DISCUSSION

Within the TRADITION project, we propose to shift the focus from a unidimensional outcome measure towards a composite measure as primary outcome measure to evaluate the efficacy of currently used subthreshold SCS paradigms. The lack of methodologically rigorous trials exploring the clinical efficacy and socio-economic consequences of subthreshold SCS paradigms is pressing, especially in light of the growing burden of PSPS-T2 on the society.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05169047. Registered on December 23, 2021.

Following Evidence-Based Recommendations for Perioperative Pain Management after Cesarean Section Is Associated with Better Pain-Related Outcomes: Analysis of Registry Data

Women who have had a Cesarean Section (CS) frequently report severe pain and pain-related interference. One reason for insufficient pain treatment might be inconsistent implementation of evidence-based guidelines. We assessed the association between implementing three elements of care recommended by guidelines for postoperative pain management and pain-related patient-reported outcomes (PROs) in women after CS. The analysis relied on an anonymized dataset of women undergoing CS, retrieved from PAIN OUT. PAIN OUT, an international perioperative pain registry, provides clinicians with treatment assessment methodology and tools for patients to assess multi-dimensional pain-related PROs on the first postoperative day. We examined whether the care included [i] regional anesthesia with a neuraxial opioid OR general anesthesia with wound infiltration or a Transvesus Abdominis Plane block; [ii] at least one non-opioid analgesic at the full daily dose; and [iii] pain assessment and recording. Credit for care was given only if all three elements were administered (= “full”); otherwise, it was “incomplete”. A “Pain Composite Score-total” (PCStotal), evaluating outcomes of pain intensity, pain-related interference with function, and side-effects, was the primary endpoint in the total cohort (women receiving GA and/or RA) or a sub-group of women with RA only. Data from 5182 women was analyzed. “Full” care was administered to 20% of women in the total cohort and to 21% in the RA sub-group. In both groups, the PCStotal was significantly lower compared to “incomplete” care (p < 0.001); this was a small-to-moderate effect size. Administering all three elements of care was associated with better pain-related outcomes after CS. These should be straightforward and inexpensive for integration into routine care after CS. However, even in this group, a high proportion of women reported poor outcomes, indicating that additional work needs to be carried out to close the evidence-practice gap so that women who have undergone CS can be comfortable when caring for themselves and their newborn.

Maximizing treatment efficacy through patient stratification in neuropathic pain trials

Treatment of neuropathic pain remains inadequate despite the elucidation of multiple pathophysiological mechanisms and the development of promising therapeutic compounds. The lack of success in translating knowledge into clinical practice has discouraged pharmaceutical companies from investing in pain medicine; however, new patient stratification approaches could help bridge the translation gap and develop individualized therapeutic approaches. As we highlight in this article, subgrouping of patients according to sensory profiles and other baseline characteristics could aid the prediction of treatment success. Furthermore, novel outcome measures have been developed for patients with neuropathic pain. The extent to which sensory profiles and outcome measures can be employed in routine clinical practice and clinical trials and across distinct neuropathic pain aetiologies is yet to be determined. Improvements in animal models, drawing on our knowledge of human pain, and robust public-private partnerships will be needed to pave the way to innovative and effective pain medicine in the future.

Spinal Cord Stimulation-Naïve Patients vs Patients With Failed Previous Experiences With Standard Spinal Cord Stimulation: Two Distinct Entities or One Population?

INTRODUCTION

Nowadays, the success of spinal cord stimulation (SCS) is evaluated separately in patients who have previous experiences with standard SCS and in SCS-naïve patients. Nevertheless, it is yet to be evaluated whether both patient groups are effectively distinct patient groups. Therefore, the aims of this study are twofold: 1) Are there clusters in the data to distinguish between both patient groups? 2) Can we discriminate both patient groups based on routinely collected clinical parameters?

MATERIALS AND METHODS

Baseline data from the Discover study were used, in which 263 patients with persistent spinal pain syndrome type 2 were included (185 neurostimulation-naïve patients and 78 patients with previous SCS experience). Pain intensity scores for low back and leg pain, functional disability, medication use, and health-related quality of life utility scores were used in the analysis. Model-based clustering was performed on standardized data. Discriminant analysis was performed with linear and quadratic discriminant analysis, with leave-one-out cross-validation to evaluate model performance.

RESULTS

Model-based clustering revealed two different clusters in the data. None of the clusters clearly separated SCS-naïve patients from patients with previous SCS experience. Linear discriminant analysis resulted in a leave-one-out cross-validation error rate of 30.0% to discriminate between both patient groups, based on routinely collected clinical parameters.

CONCLUSIONS

Clustering analysis did not result in clusters that separate SCS-naïve patients from patients with previous SCS experience. This may suggest that both patient groups should not be considered as two different patient groups when comparing them on routine clinical parameters, with potentially profound implications for research and clinical settings.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the Discover study is NCT02787265.

Gradation of Clinical Holistic Response as New Composite Outcome to Evaluate Success in Spinal Cord Stimulation Studies for Pain

INTRODUCTION

The most prominent outcome measurement in the field of neuromodulation is pain relief. Nevertheless, the number of studies that rely on composite outcomes has increased. The aims of this study are twofold: (1) to evaluate which measures are important to include in a composite outcome and (2) to develop this new composite outcome to evaluate the degree of being a clinical holistic responder with a corresponding minimal clinical important difference (MCID).

MATERIALS AND METHODS

Data from patients with persistent spinal pain syndrome type 2 treated with High-Dose Spinal Cord Stimulation (HD-SCS) were used. Pain intensity for low back and leg pain, disability, health-related quality of life, medication use, and patient satisfaction were measured at baseline and after 12 months of HD-SCS. Exploratory and Confirmatory Factor Analyses were used to evaluate which measures should be included in the composite outcome. Anchor-based and distribution-based methods were applied to determine the MCID of the newly developed outcome measurement.

RESULTS

A three-factor model was the most appropriate for this data set, in which leg pain intensity, EQ5D VAS, and disability had the largest loading on these factors. A clinical holistic outcome was created with a total score ranging from 0 (=better [no pain, no disability, and perfect health status]) to 300 (=worse [maximal pain, maximal disability, and worst health status]). The MCID value based on an absolute change score from baseline up to 12 months of HD-SCS was 87.97. When calculating with percentage changes, a MCID value of 48.4% was revealed.

CONCLUSIONS

This new composite outcome evaluating the degree of deviation from being a holistic responder is a step toward a meaningful, overall outcome assessment for patients who are treated with SCS. Further studies to evaluate the psychometric properties and the generalizability toward other patient populations still need to be performed.

Analgesic use and favourable patient-reported outcome measures after paediatric surgery: an analysis of registry data

BACKGROUND

Pain after paediatric appendectomy and tonsillectomy is often undertreated. Benchmarking of hospitals could reveal which measures are associated with improved patient- or parent-reported pain-related outcomes.

METHODS

A total of 898 anonymised cases from 11 European hospitals participating in PAIN OUT infant were analysed. The children completed a questionnaire on patient-reported outcomes (PROs) 24 h after surgery. According to a composite PRO measure, including pain intensity and pain-related interference, hospitals were allocated to Group I (favourable results), II (average results), and III (unfavourable results). Benchmarking of hospital groups was performed investigating process variables (dosing of non-opioid analgesics, opioids, and dexamethasone) associated with PROs, side-effects, and children's perception of care. Variables associated with PROs were analysed using multinomial regression analysis with the PRO score-related hospital group as a dependent variable (estimated odds ratios [OR], 95% confidence interval [CI]).

RESULTS

During the first 24 h after surgery, 1.2 (1.1-1.3) full daily doses of non-opioid analgesics (non-steroidal anti-inflammatory drug [NSAID], paracetamol, metamizole) were administered in group I and 0.7 (0.6-0.8) in group III (P<0.001). Intraoperative dexamethasone was administered to 70.1 and 52.6% of the children in Group I and Group III, respectively (P<0.001). A lower number of full daily doses of non-opioid analgesics: 0.22 [0.15-0.31]), less dexamethasone (0.49 [0.33-0.71]), fewer non-opioid analgesics before the end of surgery (0.37 [0.22-0.62]) and higher opioid doses were associated with hospital allocation to group III vs group I (Nagelkerke's R²=0.433).

CONCLUSIONS

The results indicated substantial deficits in the concept, application, and dosing of analgesics in paediatric patients after surgery. Timely administration of adequate analgesic doses can easily be introduced into daily clinical practice.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov NCT02083835.

Rethinking the definition of chronic postsurgical pain: composites of patient-reported pain-related outcomes vs pain intensities alone

ABSTRACT

Chronic postsurgical pain (CPSP) is defined by pain intensity and pain-related functional interference. This study included measures of function in a composite score of patient-reported outcomes (PROs) to investigate the incidence of CPSP. Registry data were analyzed for PROs 1 day and 12 months postoperatively. Based on pain intensity and pain-related interference with function, patients were allocated to the groups " CPSPF " (at least moderate pain with interference), " mixed " (milder symptoms), and " no CPSPF ". The incidence of CPSPF was compared with CPSP rates referring to published data. Variables associated with the PRO-12 score (composite PROs at 12 months; numeric rating scale 0-10) were analyzed by linear regression analysis. Of 2319 patients, 8.6%, 32.5%, and 58.9% were allocated to the groups CPSPF , mixed , and no CPSPF , respectively. Exclusion of patients whose pain scores did not increase compared with the preoperative status, resulted in a 3.3% incidence. Of the patients without pre-existing pain, 4.1% had CPSPF. Previously published pain cutoffs of numeric rating scale >0, ≥3, or ≥4, used to define CPSP, produced rates of 37.5%, 9.7%, and 5.7%. Pre-existing chronic pain, preoperative opioid medication, and type of surgery were associated with the PRO-12 score (all P < 0.05). Opioid doses and PROs 24 hours postoperatively improved the fit of the regression model. A more comprehensive assessment of pain and interference resulted in lower CPSP rates than previously reported. Although inclusion of CPSP in the ICD-11 is a welcome step, evaluation of pain characteristics would be helpful in differentiation between CPSPF and continuation of pre-existing chronic pain.

Combining Awake Anesthesia with Minimal Invasive Surgery Optimizes Intraoperative Surgical Spinal Cord Stimulation Lead Placement

Spinal cord stimulation (SCS) is an effective and validated treatment to address chronic refractory neuropathic pain in persistent spinal pain syndrome-type 2 (PSPS-T2) patients. Surgical SCS lead placement is traditionally performed under general anesthesia due to its invasiveness. In parallel, recent works have suggested that awake anesthesia (AA), consisting of target controlled intra-venous anesthesia (TCIVA), could be an interesting tool to optimize lead anatomical placement using patient intra-operative feedback. We hypothesized that combining AA with minimal invasive surgery (MIS) could improve SCS outcomes. The goal of this study was to evaluate SCS lead performance (defined by the area of pain adequately covered by paraesthesia generated via SCS), using an intraoperative objective quantitative mapping tool, and secondarily, to assess pain relief, functional improvement and change in quality of life with a composite score. We analyzed data from a prospective multicenter study (ESTIMET) to compare the outcomes of 115 patients implanted with MIS under AA (MISAA group) or general anesthesia (MISGA group), or by laminectomy under general anesthesia (LGA group). All in all, awake surgery appears to show significantly better performance than general anesthesia in terms of patient pain coverage (65% vs. 34-62%), pain surface (50-76% vs. 50-61%) and pain intensity (65% vs. 35-40%), as well as improved secondary outcomes (quality of life, functional disability and depression). One step further, our results suggest that MISAA combined with intra-operative hypnosis could potentialize patient intraoperative cooperation and could be proposed as a personalized package offered to PSPS-T2 patients eligible for SCS implantation in highly dedicated neuromodulation centers.

A 6-Month Home-Based Functional Electrical Stimulation Program for Foot Drop in a Post-Stroke Patient: Considerations on a Time Course Analysis of Walking Performance

Foot drop is a common disability in post-stroke patients and represents a challenge for the clinician. To date, ankle foot orthosis (AFO) combined with conventional rehabilitation is the gold standard of rehabilitation management. AFO has a palliative mechanical action without actively restoring the associated neural function. Functional electrical stimulation (FES), consisting of stimulation of the peroneal nerve pathway, represents an alternative approach. By providing an FES device (Bioness L-300, BIONESS, Valencia, CA, USA) for 6 months to a post-stroke 22-year-old woman with a foot drop, our goal was to quantify its potential benefit on walking capacity. The gait parameters and the temporal evolution of the speed were collected with a specific connected sole device (Feet Me^®) during the 10-m walking, the time up and go, and the 6-minute walking tests with AFO, FES, or without any device (NO). As a result, the walking speed changes on 10-m were clinically significant with an increase from the baseline to 6 months in AFO (+0.14 m.s⁻¹), FES (+0.36 m.s⁻¹) and NO (+0.32 m.s⁻¹) conditions. In addition, the speed decreased at about 4-min in the 6-minute walking test in NO and AFO conditions, while the speed increased in the FES conditions at baseline and after 1, 3, and 6 months. In addition to the walking performance improvement, monitoring the gait speed in an endurance test after an ecological rehabilitation training program helps to examine the walking performance in post-stroke patients and to propose a specific rehabilitation program.

Strategies to manage auxiliary pain medications in chronic pain trials: a topical review

Chronic pain trials commonly allow auxiliary pain medications such as rescue and concomitant analgesics in addition to the randomized treatment. Changes in auxiliary pain medications after randomization represent intercurrent events that may affect either the interpretation or the existence of the measurements associated with the clinical question of interest, complicating the assessment of treatment efficacy. In chronic pain trials, pain intensity typically varies and patients may take the auxiliary medications 1 day but not the next or increase and decrease the dosages temporarily while continuing their randomized study medication. This distinctive feature of auxiliary pain medications as an intercurrent event has received little attention in the literature. Further clarifications on how to manage these issues are therefore pressing. Here we provide perspectives on issues related to auxiliary pain medication-related intercurrent events in randomized controlled chronic pain trials considering the strategies suggested in the E9(R1) addendum to the ICH guideline on statistical principles for clinical trials.

Benefit-risk assessment and reporting in clinical trials of chronic pain treatments: IMMPACT recommendations

ABSTRACT

Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. This article was motivated by an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting and is based on the expert opinion of those who attended. In addition, a review of the benefit-risk assessment tools used in published chronic pain RCTs or highlighted by key professional organizations (ie, Cochrane, European Medicines Agency, Outcome Measures in Rheumatology, and U.S. Food and Drug Administration) was completed. Overall, the review found that benefit-risk metrics are not commonly used in RCTs of chronic pain despite the availability of published methods. A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.

The Effect of Duloxetine on Mechanistic Pain Profiles, Cognitive Factors, and Clinical Pain in Patients with Painful Knee Osteoarthritis - A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

BACKGROUND

Duloxetine is indicated in the management of pain in osteoarthritis. Evidence suggests that duloxetine modulate central pain mechanisms and cognitive factors, and these factors are assumed contributing to the analgesic effect. This proof-of-mechanism, randomized, placebo-controlled, crossover, double-blinded trial evaluated the effect of duloxetine on quantitative sensory testing (QST), cognitive factors, and clinical pain in patients with osteoarthritis and to predict the analgesic effect.

METHODS

Twenty-five patients completed this cross-over study with either 18-weeks duloxetine (maximum 60 mg/daily) followed by placebo or vice-versa. Pressure pain thresholds, temporal summation of pain, and conditioned pain modulation were assessed using cuff algometry. The Hospital Anxiety and Depression Scale and the Pain Catastrophizing Scale evaluated cognitive factors. Clinical pain was assessed using Brief Pain Inventory and Western Ontario and McMaster Universities Osteoarthritis Index. Linear regression models were used to predict the analgesic effect of duloxetine.

RESULTS

Depending on the clinical pain outcome, 40-68% of patients were classified as responders to duloxetine. Linear regression models predicted the analgesic effect (predictive value of 45-75% depending on clinical pain outcome parameter) using a combination of pre-treatment QST parameters, cognitive factors, and clinical pain. No significant changes were found for QST, cognitive factors, or clinical pain on a group level when comparing duloxetine to placebo.

CONCLUSION

A combination of pre-treatment QST, cognitive factors, and clinical pain was able to predict the analgesic response of duloxetine. However, in this relatively small study, duloxetine did not selectively modulate QST, cognitive factors, or clinical pain intensity when compared with placebo.

Real-world evidence of sustained improvement following 60-day peripheral nerve stimulation treatment for pain: a cross-sectional follow-up survey

Objective: This study presents real-world data from a cross-sectional follow-up survey of patients who previously received 60-day peripheral nerve stimulation (PNS) treatment for pain. Materials & methods: A survey including validated pain and other related outcome measures was distributed to patients who previously underwent implantation of temporary PNS leads for 60-day PNS treatment. Results: Among survey respondents who were at least 3 months from the start of treatment, most reported sustained clinically significant improvements in pain and/or quality of life, with the length of follow-up at the time of survey completion ranging from 3 to 30 months. Conclusion: These real-world data support recent prospective studies indicating that 60-day percutaneous PNS provides significant and sustained relief across a wide range of pain conditions.

Research approaches for evaluating opioid sparing in clinical trials of acute and chronic pain treatments: Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials recommendations

ABSTRACT

Randomized clinical trials have demonstrated the efficacy of opioid analgesics for the treatment of acute and chronic pain conditions, and for some patients, these medications may be the only effective treatment available. Unfortunately, opioid analgesics are also associated with major risks (eg, opioid use disorder) and adverse outcomes (eg, respiratory depression and falls). The risks and adverse outcomes associated with opioid analgesics have prompted efforts to reduce their use in the treatment of both acute and chronic pain. This article presents Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) consensus recommendations for the design of opioid-sparing clinical trials. The recommendations presented in this article are based on the following definition of an opioid-sparing intervention: any intervention that (1) prevents the initiation of treatment with opioid analgesics, (2) decreases the duration of such treatment, (3) reduces the total dosages of opioids that are prescribed for or used by patients, or (4) reduces opioid-related adverse outcomes (without increasing opioid dosages), all without causing an unacceptable increase in pain. These recommendations are based on the results of a background review, presentations and discussions at an IMMPACT consensus meeting, and iterative drafts of this article modified to accommodate input from the co-authors. We discuss opioid sparing definitions, study objectives, outcome measures, the assessment of opioid-related adverse events, incorporation of adequate pain control in trial design, interpretation of research findings, and future research priorities to inform opioid-sparing trial methods. The considerations and recommendations presented in this article are meant to help guide the design, conduct, analysis, and interpretation of future trials.

A Novel Multi-Dimensional Clinical Response Index Dedicated to Improving Global Assessment of Pain in Patients with Persistent Spinal Pain Syndrome after Spinal Surgery, Based on a Real-Life Prospective Multicentric Study (PREDIBACK) and Machine Learning Techniques

The multidimensionality of chronic pain forces us to look beyond isolated assessment such as pain intensity, which does not consider multiple key parameters, particularly in post-operative Persistent Spinal Pain Syndrome (PSPS-T2) patients. Our ambition was to produce a novel Multi-dimensional Clinical Response Index (MCRI), including not only pain intensity but also functional capacity, anxiety-depression, quality of life and quantitative pain mapping, the objective being to achieve instantaneous assessment using machine learning techniques. Two hundred PSPS-T2 patients were enrolled in the real-life observational prospective PREDIBACK study with 12-month follow-up and received various treatments. From a multitude of questionnaires/scores, specific items were combined, as exploratory factor analyses helped to create a single composite MCRI; using pairwise correlations between measurements, it appeared to more accurately represent all pain dimensions than any previous classical score. It represented the best compromise among all existing indexes, showing the highest sensitivity/specificity related to Patient Global Impression of Change (PGIC). Novel composite indexes could help to refine pain assessment by informing the physician's perception of patient condition on the basis of objective and holistic metrics, and also by providing new insights regarding therapy efficacy/patient outcome assessments, before ultimately being adapted to other pathologies.

Exploring why people with back pain use the pain management strategies they do: Is research looking in the wrong places?

 

Low back pain (LBP) is a significant issue with considerable impact on people's lives and economies. A plethora of research investigates interventions to manage LBP. However, despite considerable knowledge translation efforts, individuals with the condition frequently use management strategies considered to be 'ineffective'. To address this concern, our aim was to explore why people with LBP choose the management strategies they do.

METHODS

We employed a predominantly inductive, descriptive qualitative design. We interviewed 20 Australian adults who have, or have had, LBP to investigate the management strategies they have employed and why. Data were analysed thematically.

RESULTS

Analysis identified three interrelated themes that highlight that participants chose management strategies, at least in part, because they: 1) reduce symptoms in the very short-term (e.g., immediately, a few hours); 2) have effects beyond the condition (e.g., low cost, lack of negative side effects, convenience, social effects); and 3) are pleasurable.

DISCUSSION

These outcomes suggest that people with LBP are likely to have nuanced reasons for choosing the management strategies they use, and this can contrast with the outcomes tested in empirical studies. Our findings suggest that researchers may need to broaden or rethink which outcomes they measure and how, including by meaningfully engaging consumers in research design. Further, clinicians could better explore their patient's reasons for using the strategies they do, before suggesting they discard existing strategies, or offering new ones.