Background: This meta-analysis is an update to a seminal meta-analysis on racial/ethnic disparities in pain treatment in the United States (US) published in 2012. Since then, literature has accumulated on the topic and important policy changes were made. Objective: Examining racial/ethnic disparities in pain management and investigating key moderators of the association between race/ethnicity and pain outcomes in the US. Methods: We performed a systematic search of publications (between January 2011 and February 2021) from the Scopus database. Search terms included: race, racial, racialized, ethnic, ethnicity, minority, minorities, minoritized, pain treatment, pain management, and analgesia. All studies were observational, examining differences in receipt of pain prescription medication in various settings, across racial or ethnic categories in US adult patient populations. Two binary analgesic outcomes were extracted: 1) prescription of “any” analgesia, and 2) prescription of “opioid” analgesia. We analyzed these outcomes in two populations: 1) Black patients, with White patients as a reference; and 2) Hispanic patients, with non-Hispanic White patients as a reference. Results: The meta-analysis included twelve studies, and the systematic review included forty-three studies. Meta-analysis showed that, compared to White patients, Black patients were less likely to receive opioid analgesia (OR 0.83, 95% CI [0.73– 0.94]). Compared to non-Hispanic White patients, Hispanic patients were less likely to receive opioid analgesia (OR 0.80, 95% CI [0.72– 0.88]). Conclusion: Despite a decade’s gap, the findings indicate persistent disparities in prescription of, and access to opioid analgesics for pain among Black and Hispanic populations in the US.

Background: Clinical predictors of pain relief with 60-day peripheral nerve stimulation (PNS) remained undefined. Identifying the factors associated with treatment outcomes may improve patient selection and optimize results. Objective: This study examined baseline physical activity, pain, disability, and psychological factors influencing early versus delayed response and non-response to a 60-day PNS. Methods: A prospective, multicenter, observational cohort study was conducted on 73 patients who consecutively received a 60-day PNS. Baseline assessments included pain (numeric rating scale [NRS]), disability (Oswestry Disability Index [ODI]), psychological profiles (Pain Self-Efficacy Questionnaire, PSEQ; Pain Catastrophizing Scale, PCS), and physical activity (physical activity vital signs [PAVS]). Logistic regression and principal component analysis were used to identify the predictors of response phenotypes. Results: Early (≥ 50% pain relief within 7– 14 days of PNS implant that is sustained through the entire 60-day period) and delayed (< 50% pain relief in the first 14 days but eventually reaching ≥ 50% before the end of the 60 days) responder rates were 26% and 43%, respectively. Non-responders (< 50% pain relief at the end of the 60-day treatment period) comprised 30.1% of the group. Predictors of early response included high physical activity (OR=4.22, p=0.0006, Area Under the Curve [AUC] =0.81), high pain self-efficacy (OR=1.12, p=0.0004, AUC=0.86), and low catastrophizing (OR=0.88, p=0.0003, AUC=0.86). A delayed response was associated with a longer chronic pain duration (OR=0.83, p=0.027) and high baseline ODI (OR=0.43, p=0.002; AUC=0.79). Nonresponse was linked to psychological distress (eigenvalue =3.23, 40.3% variance), opioid dependency, and morbid obesity (eigenvalue =1.63, 20.4% variance). Conclusion: This real-world study showed that baseline physical activity, psychological resilience, and pain behaviors predicted response to a 60-day PNS. Non-responders presented with psychological distress, morbid obesity, and opioid dependence. These findings may refine patient selection and help to set treatment expectations for 60-day PNS. Plain Language Summary: Peripheral nerve stimulation (PNS) is a promising therapy for chronic pain. However, it is difficult to predict which patients will benefit the most. This study examined patient characteristics that influence response (early and delayed) or nonresponse to 60-day PNS treatment. Patients from multiple health systems completed surveys before treatment to assess pain levels, physical activity, disability, and psychological factors. Our research team analyzed medical records to identify predictors of successful response and nonresponse to a 60-day PNS treatment. The results showed that:Early responders (patients who benefited quickly) had higher physical activity levels, greater confidence in managing pain (pain self-efficacy), and lower pain-related distress (catastrophizing).Delayed responders (patients who improved gradually) had longer histories of chronic pain and more severe baseline pain disability.Non-responders (patients who did not experience significant pain relief) tended to exhibit higher psychological distress, opioid dependence, and morbid obesity. These findings suggest that baseline physical activity, psychological coping, and behavioral factors could help to identify ideal candidates for PNS therapy. Understanding these predictors may improve patient selection, treatment expectations, and long-term pain management strategies.

The availability of knowledge about the effects of buprenorphine on pain perception in healthy adults could help investigators select experimental tests with evidence of responsiveness to buprenorphine in nondiseased states. The purpose of this meta-narrative systematic review is to summarize the effects of buprenorphine on pain perception in healthy adults. Comprehensive database searches were conducted from inception dates through July 16, 2024. Inclusion criteria included all study designs involving healthy adults receiving buprenorphine and tests of pain perception. Risk of bias was assessed using a tool developed for randomized controlled trials (RCTs). A meta-narrative approach was used due to high levels of clinical heterogeneity. A total of 10 RCTs were included, and healthy adults comprised the comparator groups in all trials. Three RCTs had a low risk of bias, 6 had some concerns, and 1 had a high risk of bias. Six RCTs used intravenous buprenorphine, 3 used transdermal, and 1 study used intravenous and sublingual buprenorphine. The effects of buprenorphine on pain perception are influenced by the route of administration, dose, and pain stimulus modality. Considerable differences exist in the effects of intravenous and transdermal buprenorphine, but only 1 study used sublingual buprenorphine, which limited comparison with the other drug formulations. Based on these findings, recommendations for clinical trials are proposed. These recommendations should be cautiously interpreted due to the clinical heterogeneity, but they provide a framework for advancing the use of experimental pain tests in trials of buprenorphine involving comparator groups of healthy adults.

Background: Wearable inertial measurement units (IMUs) offer scalable, objective gait assessment, but detailed stride-level validation against motion capture and their ability to reflect physical activity (PA)–related gait differences in knee osteoarthritis (KOA) remain incompletely characterized. Objective: This study aimed to evaluate the technical validity of foot-mounted IMU–derived gait parameters compared with optical motion capture in individuals with KOA and healthy controls. As a secondary exploratory aim, we assessed whether IMU-derived gait parameters differed across self-reported PA levels. Methods: In this pilot cross-sectional validation study, 20 participants (KOA: n=10, 50%; healthy controls: n=10, 50%) completed 3 standardized walking conditions (self-paced, fast-paced, and endurance-equivalent). IMU-derived gait parameters were compared with motion capture at the stride level (≥5000 strides) using Pearson correlation, intraclass correlation coefficients (ICCs), mean absolute error, root mean square error, and Bland-Altman analysis. Participants completed the Stanford Brief Activity Survey to categorize PA level. Secondary analyses emphasized effect sizes and 95% CIs given the pilot design. Feasibility was assessed by protocol completion, data completeness, and tolerability. Results: IMU-derived gait speed demonstrated strong agreement with motion capture ( r =0.99; ICC=0.98, 95% CI 0.95‐0.99; mean absolute error=0.07 m/s; bias=0.01 m/s; 95% limits of agreement −0.14 to 0.16 m/s). Stride length and cadence showed similarly high agreement (ICC range 0.96‐0.97). All participants completed the protocol with minimal adverse events. Exploratory analyses suggested that participants reporting higher PA demonstrated directionally faster gait speed and longer stride length, with small-to-moderate effect sizes, whereas inactive participants exhibited higher stance-related rhythm parameters. Conclusions: Foot-mounted IMUs demonstrated strong stride-level agreement with motion capture across walking conditions, supporting technical validity in both KOA and healthy populations. Exploratory findings suggest that wearable-derived gait parameters may reflect activity-related differences; however, larger longitudinal studies are required to confirm these preliminary signals.