Frontiers in Pain Research

Cervical spondylotic myelopathy (CSM) is the most common cause of nontraumatic spinal cord dysfunction in adults and is an increasingly important source of disability as populations age. Gabapentin is widely prescribed for neuropathic pain and may therefore be used for symptoms related to known or undiagnosed CSM. However, there is sparse evidence related specifically to gabapentin's use for CSM-related pain. We investigate gabapentin use and trends over time in patients with CSM compared to matched controls. We observed that gabapentin prescriptions were higher in CSM patients compared to controls across two multi-hospital datasets. These results highlight the need for further research into pharmacologic treatment for chronic pain in CSM.

Objective: To evaluate the clinical efficacy of non-invasive electrical pulsed radiofrequency (PRF) stimulation on diagnostic thresholds and subjective pain in chronic, pedal diabetic peripheral neuropathy (DPN). Methods: A randomized, single-blind, placebo-controlled trial (ClinicalTrials.gov: NCT07725419) enrolled 92 patients with pedal DPN naive to PRF and scoring [&ge;] 4/10 on the Douleur Neuropathique 4 (DN4) test. Participants received either active PRF stimulation (n = 46) or a non-stimulating placebo (n = 46) applied bilaterally to the sciatic nerve in the popliteal fossa for 10 minutes per limb, once weekly for three weeks. The primary outcome was clinical neuropathic resolution (DN4 < 4). Secondary outcomes included subjective pain tracking via the Brief Pain Inventory-Short Form (BPI-SF) Worst Pain scale over a 6-month follow-up window. Missing data were handled via Non-Responder Imputation (NRI). Longitudinal continuous trajectories were modeled using Linear Mixed-Effects Models (LMMs) adjusted for age, gender, and baseline medication use. Results: In the Intention-to-Treat population (N = 92), a significant diagnostic responder effect occurred at 3 months, with 39.1% of active patients dropping below the diagnostic threshold for neuropathy (DN4 < 4) versus 19.6% of placebo controls (p = 0.039). For subjective pain, 47.7% of active patients achieved a Minimally Clinically Important Difference ([&ge;] 3-point reduction) in BPI Worst Pain at 1 month compared to 19.4% of placebo controls (p = 0.008). Multivariable logistic regression identified active treatment as a significant independent predictor of clinical response (Adjusted OR = 4.86; 95% CI: 1.56 to 17.53; p = 0.010). Continuous LMM tracking confirmed a statistically significant treatment-by-timepoint interaction for BPI Worst Pain at 1 month (p = 0.046). Conclusion: A brief, three-week course of non-invasive PRF stimulation serves as a safe, effective, non-pharmacological adjunct that aids in managing the diagnostic presentation of neuropathic pain and mitigates worst pain experiences in patients suffering from pedal DPN.

Background: Neuropathic pain (NP) remains a therapeutic challenge, with conventional repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) yielding a response rate of approximately 40%. Personalised targeting based on dysfunctional neurocircuitry offers a promising strategy to enhance efficacy, yet its application in NP is unexplored. This open-label trial investigated a novel targeting approach guided by the recently described cingulo-opercular and somato-cognitive action (CON-SCAN) network, a circuit integrating cognitive and affective dimensions of pain. Methods: Twenty patients with NP received 10 sessions of M1-rTMS over two weeks, with the stimulation site individually localised based on maximal functional connectivity to a CON template. Results: Increased CON-SCAN connectivity from baseline to post-treatment was associated with reduction in pain interference, anxiety and depression scores. The response rate was 50% post-treatment, which was maintained at the 1-month follow-up. Improvements were also observed in neuropathic pain symptoms, negative affect, and overall health. Conclusions: As the first connectivity-guided rTMS trial for NP, this study provides preliminary evidence that personalised targeting of the CON-SCAN network is feasible and associated with the analgesic effects of M1-rTMS, supporting further investigation in randomised controlled trials. Trial registration: Chinese Clinical Trial Registry, ChiCTR2500104679. Registered 20 June 2025, http://www.chictr.org.cn. Chinese Clinical Trial Registry, ChiCTR2400094568. Registered 24 December 2024, http://www.chictr.org.cn. Keywords: Personalised TMS; Pain; M1; CON; SCAN

Background: Fluctuations in pain intensity are intrinsic to non-specific chronic low back pain (nsCLBP). Nevertheless, pain fluctuations have rarely been considered when investigating pathophysiological mechanisms. Therefore, a novel study protocol was developed and implemented to systematically assess the impact of fluctuating pain states on pain-related measures. Methods: The final study cohort consisted of 45 nsCLBP patients and 47 age- and sex-matched healthy controls (HCs). Patients participated in three visits, conducted during different pain states (i.e. clinically relevant pain, low-intensity clinical pain / pain-free, clinically irrelevant pain induced using a Qutenza 8% capsaicin patch). Pain fluctuations were monitored through online assessments every four days and guided the pseudorandomized visit scheduling. HCs participated in a single visit. Each study visit comprised a multimodal battery of pain-related measures. Results: 93.33% of patients completed all three visit types in a pseudorandomized order (chi-squared=1.50, p=0.826). Visit scheduling was possible due to the high self-report adherence (median=93.48%), unrelated to self-report burden (rho=-0.097, p=0.53). Study visits were conducted during different pain states, as indicated by: i) the significantly higher low back pain intensity in the clinically relevant pain visit (mean[SD]: 3.98[0.90]), compared to the low-intensity clinical pain (1.03[0.86]) and clinically irrelevant pain (1.13[0.82]) visits (p-values<0.001), as well as by ii) the successful induction of a moderate-to-high clinically irrelevant pain across assessments. Conclusion: Despite scheduling complexity and pain state transition uncertainty, a pain state-dependent pseudorandomized study design is feasible and could improve the understanding of nsCLBP mechanisms.

Myofascial pain syndrome (MPS) is a major cause of chronic neck pain, with tissue ischemia implicated as a contributing factor. This prospective, single-arm interventional study evaluated the analgesic effect of ultrasound-guided fascia hydrorelease (US-FHR) performed around arteries supplying the neck in patients with chronic neck MPS. Thirteen adults (median age 53.0 years; 38.5% female) underwent US-FHR targeting the perivascular fascia of either the transverse cervical or dorsal scapular artery using 2 mL of normal saline. Pain intensity was assessed by visual analog scale (VAS) at rest and during movement; disability by the 5-item Pain Disability Index, Japanese version (PDI-5-J); and arterial blood flow volume before and after the procedure. The primary outcome, pain VAS during movement, decreased from 49.0 mm (interquartile range [IQR], 44.5-64.0) at baseline to 22.0 mm (IQR, 14.5-31.5) at 15 min and 22.0 mm (IQR, 14.0-34.0) at 1 week (Hodges&-Lehmann median difference, 30.5 mm [95% CI, 24.5 to 36.5] and 28.5 mm [95% CI, 18.5 to 37.0]; both P < 0.001). Pain VAS at rest improved from 21.0 mm (IQR, 13.0-43.5) to 8.0 mm at 15 min and 1 week (median difference, 14.5 mm [95% CI, 9.0 to 24.0; P = 0.001] and 13.5 mm [95% CI, 6.0 to 21.0; P = 0.007]). PDI-5-J decreased from 17.0 (IQR, 10.5-23.0) to 13.0 (IQR, 4.0-17.5) at 1 week (median difference, 5 [95% CI, 2 to 8; P = 0.004]). Blood flow volume increased from 11.2 mL/min (IQR, 4.5-14.4) to 17.2 mL/min (IQR, 6.1-23.7) immediately after US-FHR (median difference, +4.1 mL/min [95% CI, +2.5 to +8.9; P = 0.001]), although transient. One patient experienced transient bleeding that was promptly controlled. In this single-arm feasibility study, US-FHR around the target artery was simple and safe to perform and was associated with reduced neck pain. Because the study lacked a control group, these preliminary findings should be regarded as hypothesis-generating and require confirmation in controlled trials; they may also inform the future evaluation of MPS in other anatomical regions. Trial registration: UMIN Clinical Trials Registry, UMIN000053612.

Validated measures of pain catastrophizing primarily assess catastrophizing as a stable trait. However, emerging evidence suggests catastrophizing fluctuates with context, highlighting a need for ecologically valid methods to capture it. This study evaluated large language models (LLMs) as implicit markers of catastrophizing from free text responses from ninety-one adults with chronic pain receiving long-term opioid therapy (57.3 percent Female; mean age = 60.5 years). Patients completed baseline measures, including the trait pain catastrophizing scale (PCS), followed by a 10 minute writing task after random assignment to a negative, positive, or neutral pain-coping condition. State affect and pain were assessed before and after writing tasks and again after a cold pressor task (4 degrees C; <= 2 minutes). A state PCS followed the cold pressor task. Free text responses were analyzed using four LLMs (Claude Opus 4; GPT Mini 4o; Llama 4 Maverick; and Gemini 2.5 Pro). ANOVA based results supported discriminant validity, as all four LLM-derived pain catastrophizing scores differentiated negative from positive and neutral pain-coping conditions. Convergent validity was model dependent; only Gemini derived scores correlated with state catastrophizing (r = .22) and pain unpleasantness (r = .23). Divergent validity was mixed. LLM derived scores were unrelated to pain intensity, but Gemini and Claude derived scores showed small correlations with trait PCS (rs = .21; 28, respectively). All LLM-derived scores also correlated with negative affect (rs range = .29 - .41), comparable in magnitude to state PCS, suggesting limited specificity. These findings provide preliminary evidence that certain LLMs may serve as implicit markers of state pain catastrophizing, but further study is needed.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and painful side effect of paclitaxel (PTX) treatment. The most common measures of painful neuropathy focus on evoked mechanical hypersensitivity, but clinically relevant ongoing pain remains understudied in preclinical models. Automated machine learning methods for pose estimation and behavioral classification have been proposed to capture non-evoked pain-like behaviors, though these approaches have primarily been applied to unilateral injury models such as spared nerve injury or unilateral inflammatory compound injection. Here, we evaluated the extent to which paclitaxel-induced CIPN affects the posture and spontaneous behavior of freely moving mice using a commercially available automated recording system (BlackBox). We found that paclitaxel-treated mice develop a broad and reproducible behavioral and postural phenotype relative to vehicle-treated controls, characterized by reduced front paw luminance and print size, increased front paw lifting, and altered body measurements consistent with a guarded posture. This phenotype was replicated across two independent cohorts and was detectable at both day 2 and day 6 following the final paclitaxel injection. To identify behavioral features specific to CIPN, we administered gabapentin, an analgesic often used to treat neuropathic pain in patients, to determine whether paclitaxel-induced behavioral changes could be attenuated. Gabapentin reduced several behavioral features in both paclitaxel-treated and vehicle-treated animals, suggesting that its effects on posture and gait are not specific pain in CIPN. These findings demonstrate that automated behavioral recording captures a robust paclitaxel-induced postural phenotype but question whether captured behaviors are indicative of ongoing pain as alleviated by gabapentin.

BACKGROUND: Myofascial Pain Syndrome (MPS) is a common musculoskeletal pain condition associated with myofascial trigger points that has been reported to occur in 30-93% of patients who present with musculoskeletal pain. The current pharmacologic treatments (such as nonsteroidal anti-inflammatory drugs [NSAIDs], muscle relaxants, and tricyclic antidepressants) are only partially effective and have side effects. Shilajit, a mineral-organic exudate from the Himalayas, has antioxidant, anti-inflammatory, mitochondrial bioenergetic, and central analgesic effects and has not previously been examined as an analgesic in any musculoskeletal pain condition. METHODS: This was an exploratory pilot clinical trial with open-label design in a single arm for an 18-month period at All India Institute of Medical Sciences (AIIMS), Rishikesh, India. Patients aged 18 to 65 years with clinically diagnosed MPS (Simons et al. 1999 criteria) and a baseline visual analog scale (VAS) score >4 were enrolled. Native Himalayan Shilajit 250 mg daily was administered as add-on therapy for 49 days. The main outcome was the percentage of participants with more than or equal to 30% VAS reduction at Day 49. The intensity of pain, the dose of analgesics consumed, and the number of trigger points were evaluated at five time points (Day 0, 12, 24, 36, 49). Throughout, adverse events were monitored. RESULTS: Of 80 enrolled participants, 76 (95.0%) completed the per-protocol analysis. Mean age was 41.25 (SD 9.05) years; 52.6% were male. A total of 56 of 76 participants (73.7%; 95% CI: 62.1-82.8%) achieved the primary endpoint. Mean VAS score declined from 6.63 (SD 1.08) at baseline to 3.63 (SD 1.72) at Day 49 (mean reduction 45.3%; Friedman Chi-square= 278.5, p<0.001). The first signs of pain reduction were seen at Day 24. The number of analgesic doses consumed decreased by 75.5% during the study period (chi-square = 126.1, p<0.001). There was a significant reduction in trigger point count from baseline to Day 49 (p=0.031) of 23.4%. One Grade 2 adverse event (gastrointestinal irritation, Day 28, resolved within 24 hours, no drug discontinuation) occurred; no serious adverse events were reported. Trial registration: CTRI/2025/06/088636. The study was not funded by any external sources. CONCLUSIONS: Native Himalayan Shilajit 250 mg/day for 49 days was associated with clinically and statistically significant reductions in pain intensity, analgesic consumption, and trigger-point burden in patients with MPS, with a favorable safety profile. These findings warrant confirmation in a larger, randomized, placebo-controlled trial.

Background: Pain relief is the principal patient-centered goal of surgery for symptomatic lumbar synovial facet cysts, yet comparative reviews have often emphasized cyst recurrence. Whether adding fusion improves postoperative pain or reduces later surgery remains uncertain. Objective: To compare decompression alone with decompression plus fusion, with postoperative back- and leg-pain outcomes as the primary domain. Methods: PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception to 2 June 2026. Comparative cohorts and case series with at least five patients were eligible. Twenty-two studies were re-extracted for VAS/NRS scores, change scores, and persistent or recurrent pain. Random-effects restricted maximum likelihood models with Hartung-Knapp inference were used; clinically distinct pain outcomes were analyzed separately. Results: Twenty-two studies (16 cohorts, 6 case series; 51,899 participants) were included. Two studies provided compatible final VAS data. Fusion did not improve postoperative back pain (MD -0.04, 95% CI -0.17 to 0.10; I2=0%) or leg pain (MD -0.03, 95% CI -0.28 to 0.21; I2=0%). Postoperative back pain (RR 0.58, 95% CI 0.14-2.30) and leg/radicular symptoms (RR 0.75, 95% CI 0.42-1.32) were also not significantly reduced. Fusion decreased confirmed cyst recurrence (RR 0.29, 95% CI 0.15-0.57) but not reoperation or subsequent lumbar surgery (RR 0.80, 95% CI 0.42-1.50). Conclusion: Current comparative evidence does not demonstrate superior postoperative pain control with routine fusion. Fusion reduces cyst recurrence without clearly reducing reoperation, supporting selective use when instability is present or anticipated.

Background. Chronic pelvic pain with involuntary pelvic-floor hypertonicity is common, disabling, and inconsistently measured, and no validated condition-specific severity instrument exists. A refractory subset has been proposed to represent a focal dystonia of the pelvic musculature, termed pelvic dystonia. Purpose. To develop the Pelvic Dystonia Severity Scale (PDSS) and evaluate its measurement properties as a patient-reported measure of pelvic-pain symptom severity and burden, following the COSMIN guidelines. Methods. Cross-sectional study with a test-retest component in 102 adults from an outpatient multidisciplinary pain practice. We assessed data quality, structural validity, internal consistency, test-retest reliability, measurement error, and construct validity against the Global Dystonia Severity Rating Scale (GDS) and Brief Pain Inventory (BPI). Because no validated diagnostic criteria exist, a clinician blinded to PDSS responses rated each participant for clinical signs of pelvic dystonia (present/possible/absent) as a provisional reference standard. Results. 100 of 102 participants (98%) returned complete data, with 0% item-level missing data. Factor analysis supported a unidimensional structure (single factor, 68.6% of variance; loadings 0.56-0.93), with high subscale intercorrelations (r = 0.81-0.97). Internal consistency (Cronbach's 0.810-0.924) and test-retest reliability (ICC 0.857-0.953) were strong. Convergent validity was supported by correlations with GDS pelvic-region items (r = 0.56-0.68) and BPI severity (r = 0.44-0.55), and discriminant validity by weak correlations with anatomically remote regions (shoulder/arm r = 0.03-0.16). PDSS scores rose monotonically across blinded clinical-signs categories (absent 14.9, possible 32.7, present 52.0; Kruskal-Wallis p < 0.001), discriminating signs-present from signs-absent participants with a very large effect (Hedges g = 2.19; ROC AUC = 0.92). Conclusion. The PDSS is a psychometrically robust, unidimensional measure of pelvic-pain symptom severity and burden with strong data quality, reliability, and construct validity. It is suitable for characterizing symptom severity and, pending responsiveness testing, for monitoring treatment. The dystonia interpretation of the underlying phenotype is discussed as a hypothesis for future neurophysiologic and longitudinal study.

Placebo analgesia varies substantially across individuals, yet the sources of this heterogeneity remain incompletely understood. Pain-reporting variability may represent an underrecognized predictor of placebo responsiveness. This study examined whether variability and reliability of pain reporting predict placebo analgesia in an experimental pain setting. Eight hundred and three participants (401 individuals with temporomandibular disorder and 400 healthy controls) completed a standardized thermal pain paradigm involving calibration, placebo conditioning, and testing phases. We obtained repeated heat temperatures (four) during thermal calibration and pain ratings during conditioning test (24 trials). We used these measurements to quantify within-person pain-reporting variability using standard deviation (SD) and coefficient of variation (CoV), and reliability using intraclass correlation coefficients (ICC). Placebo analgesia was calculated as the difference in pain ratings between control and placebo cue trials during testing. Regression models examined associations between reporter characteristics and placebo analgesia controlling for age, sex, race and experimenters. Variability of thermal pain responses during calibration did not predict placebo analgesia. Greater pain-reporting variability during conditioning was associated with reduced placebo analgesia (higher SD and CoV), and this effect was mediated by slower acquisition of the cue pain contingency. Conditioning-phase reliability was not associated with placebo analgesia, whereas three clusters of learning profiles predicted placebo effects. Thus, individual differences in pain-reporting variability during conditioning, rather than baseline sensory variability, contribute to heterogeneity in placebo analgesia. These findings suggest that variability during acquisition processing matters more than general sensory variability influencing the magnitude of placebo effects.

BackgroundThis study aimed to determine if a rat osteotomy model elicits a measurable systemic response and to utilize this profile to evaluate the mechanism of action of preemptive analgesics with translational relevance to veterinary perioperative pain management. MethodsTwenty-five male rats were randomized into five groups: Sham, Surgery Control, Robenacoxib (2 mg/kg S.C.), Amantadine (30 mg/kg P.O.), and Combination. A femoral osteotomy was performed following ARRIVE 2.0 guidelines for refinement of surgical models. Serum levels of IL-6, PGE2, and cortisol were quantified via ELISA at baseline, 1-, 3-, and 6- hours post-surgery. Postoperative pain was assessed using the Rat Grimace Scale (RGS). ResultsThe osteotomy model did not induce a significant systemic inflammatory or stress response. Serum IL-6 and cortisol levels showed no significant changes over time (IL-6: p=0.219; Cortisol: p=0.187) or between groups. While PGE2 showed a temporal increase (F=6.52, p=0.001), it was unaffected by drug treatments. In stark contrast, the model successfully produced significant pain-related behaviors in the Control group (p=0.007), which were effectively reduced by both Robenacoxib (p=0.014) and amantadine (p=0.019) monotherapies. The combination group also showed significant pain reduction compared to Control at T6 (p=0.002), with an additive effect relative to monotherapies. Correlation analysis confirmed a dissociation between systemic biomarker levels and pain scores. ConclusionThe efficacy of Robenacoxib (a COX-2 inhibitor approved for veterinary use) and amantadine in the absence of altered systemic biomarkers suggests their analgesic actions are mediated predominantly through local or neurogenic pathways, with direct implications for optimizing perioperative analgesia protocols in companion animal orthopedic surgery.

Introduction: Pain catastrophizing and pain self-efficacy are well-established predictors of health outcomes in chronic pain. Higher pain catastrophizing, a maladaptive cognitive process, predicts worse health outcomes, whereas higher pain self-efficacy, an adaptive cognitive process, predicts better health outcomes. This study examined whether pain catastrophizing and pain self-efficacy interactions predict physical and psychosocial health outcomes at 3 months and their change over 3-months among patients with chronic pain who sought care at a tertiary pain clinic. Methods: Adults with chronic pain (N = 181; 66.7% female; Mage = 58.7) completed baseline assessments of the Pain Catastrophizing Scale (PCS), Chronic Pain Self-Efficacy Scale (CPSS), and PROMIS measures of physical (pain intensity, pain interference, physical function) and psychosocial health (depression, anxiety, anger, loneliness). PROMIS measures were repeated at 3 months. Hierarchical multiple regression analyses tested PCS, CPSS, and their interaction as predictors of outcomes at 3 months and change scores from baseline to 3 months. Results: The PCS by CPSS interaction significantly improved prediction for physical function (Change in R2 = 0.02, p = .02). Higher baseline self-efficacy predicted better physical function (Beta = 0.65, p < .001), but this effect weakened with higher levels of pain catastrophizing. The interaction also predicted change scores in physical function (p = .025) but was marginal after false discovery rate correction (p = .059). Additionally, a significant interaction emerged for loneliness change scores (p = .01): higher self-efficacy predicted greater reductions in loneliness, attenuated by higher catastrophizing. Conclusion: Pain self-efficacy interacted with pain catastrophizing to predict physical function and loneliness at 3 months. Greater self-efficacy was associated with better outcomes, with associations diminished with higher levels of pain catastrophizing. Findings highlight the moderating role of adaptive and maladaptive cognitions and suggest interventions should address both processes to optimize recovery in physical and social functioning.

The Acute to Chronic Pain Signatures (A2CPS) project is a large, multisite, longitudinal observational study designed to identify biomarkers that predict the transition from acute to chronic pain following surgery in more than 2200 patients. Two participant cohorts were recruited before undergoing either knee arthroplasty or thoracic surgery. A unique feature of this study is its comprehensive evaluation of pain, including evoked and recall pain measures collected at baseline, 6-weeks, and 3-months following surgery, in addition to the primary pain outcome assessed remotely at 6 months. This paper describes the acquisition, quality control procedures, and available pain and pain sensitivity variables included in the A2CPS study. Self-report pain assessments include surgical site (i.e., index) pain intensity, pain interference and quality, spatial distribution of pain using body maps, and pain-related dysfunction specific to each cohort. Quantitative sensory testing yielded evoked pain sensitivity data including pressure pain thresholds, temporal summation of pain, dynamic mechanical allodynia, and conditioned pain modulation at both index and common sites across cohorts. Movement-evoked pain was assessed for each cohort using relevant functional tasks (knee: 10m walk and five-time-sit-to-stand tests, thoracic: deep breathing and coughing). Using baseline data from release v2.1.0, comprising approximately 1,400 participants, we evaluated interrelationships among pain variables. Overall, the A2CPS pain and pain sensitivity data provide a robust, comprehensive set of variables that supports the study goal of uncovering predictive biomarkers of post-operative chronic pain and enables broader exploration relative to other study outcomes, including imaging, psychosocial, and omics data.

Introduction: Acute low back pain is a leading cause of disability worldwide. Clinical guidelines recommend non-pharmacological therapies as first-line treatment and advise caution with opioid prescribing. However pharmacological therapies, including opioids and gabapentinoids, remain commonly used. The comparative risks of subsequent opioid use disorder (OUD) and overdose diagnosis associated with initial treatment modality in large, real-world populations is not well characterized. We estimated the incidence of new-onset OUD and overdose diagnosis among opioid-naive, Medicaid-insured adults with newly diagnosed acute low back pain and estimated the association between initial treatment modalities and subsequent OUD and overdose diagnosis risk. Methods: We conducted a retrospective cohort study using Medicaid T-MSIS Analytic files from 25 states (2016-2019). We identified opioid-naive adults with a new diagnosis of acute low back pain who initiated pharmacologic or non-pharmacologic treatment within 1 month of diagnosis. The primary outcome was incident OUD and overdose diagnosis (based on diagnosis codes in claims) during follow-up. Associations between initial treatment modality and OUD and overdose diagnosis risk were estimated using a non-parametric, doubly robust estimator to adjust for measured confounding. Results: The cohort included 525,002 opioid-naive adults initiating treatment for low back pain. The cumulative incidence of OUD and overdose diagnosis was 1.5% and 2.4% at 7 and 13 months, respectively. Compared to non-use, use of gabapentinoids during the first month of treatment was associated with the highest relative risk (increasing risk) by 130.1%, 95% confidence interval (CI): 117.8%, 142.3%), the second-highest relative risk was estimated for higher-dose opioids, defined as > 50 daily Morphine Milligram Equivalents (MME) (118.1%, 95% CI: 99.2%, 137.0%). Lower-dose, short-duration opioids ([&le;] 50 MME, [&le;] 7 days) were also associated with elevated risk, though substantially smaller in magnitude (20.8%, 95% CI: 13.8%, 27.9%). In contrast, non-pharmacologic, non-interventional therapies were associated with reduced OUD and overdose diagnosis risk, with physical therapy demonstrating the largest relative reduction of 34.0% (95% CI: -40.9%, -27.1%). Discussion: In opioid-naive Medicaid patients with acute low back pain, initial non-pharmacologic treatment was associated with reduced OUD and overdose diagnosis risk. Gabapentinoids and opioids were each associated with increased risk; for opioids, the degree of risk increased with higher doses and durations. These results support guideline recommendations favoring non-pharmacologic treatment as first-line therapy and indicate the importance of cautious prescribing when pharmacologic treatment is considered.

Chronic widespread pain (CWP) is highly prevalent among minoritized adults with clinical obesity, and symptom management is challenging. Weight loss via bariatric surgery is often recommended to improve musculoskeletal pain. However, there is significant variation in pain trajectories following bariatric surgery, and the impact of weight loss on movement-evoked pain is largely unknown. The current study aims to systematically characterize and quantify longitudinal changes in pain at rest and movement-evoked pain up to 6 months post-surgery, and to determine whether pain modulatory mechanisms, joint motion, and mechanical loading biosignatures mediate the relationship between weight loss and pain change. This study protocol details the research methodologies and procedures for a prospective observational cohort study of 60 individuals undergoing bariatric surgery for weight loss. Participants will complete questionnaires, anthropometric measurements, clinical and experimental pain testing, functional testing, and a standardized movement testing battery to assess joint motion and mechanical loading using camera-based motion capture before and at 3 and 6 months post-bariatric surgery. Generalized linear mixed models to assess the significance of changes in PAR, MEP, and all patient-reported outcome measures. Reduced models will treat the main effect of time as a fixed factor, and intra-individual repeated measures as random effects. Ethics and dissemination: This study protocol has been registered as an observational study with ClinicalTrials.gov (NCT0675386) in the United States and has been approved by the NYU Langone Health Institutional Review Board (IRB#: i21-01652) and the New York City Health + Hospitals/Bellevue Research Office (Bellevue Study ID #: STUDY00003739). Study results will be published in peer-reviewed journals and presented at national and international conferences and community events.

Abstract Background: Non-specific chronic low back pain (NSCLBP) is associated with persistent pain, reduced health-related quality of life (HRQoL), and low-grade systemic inflammation. This study examined associations among changes in inflammatory biomarkers, pain intensity, and HRQoL following a 12-week aerobic exercise programme. Methods: This secondary analysis used data from a randomized controlled trial involving 41 participants with NSCLBP (intervention, n = 21; control, n = 20). Participants received either supervised aerobic exercise plus health education or health education alone for 12 weeks. Change scores for tumour necrosis factor-alpha (TNF-), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), pain intensity, and HRQoL domains were analysed using correlation and multiple regression analyses. Results: Improvements in IL-6 (r = 0.434, p = 0.005) and hs-CRP (r = 0.444, p = 0.004) were significantly associated with improvements in pain intensity. No significant associations were observed between biomarker changes and HRQoL domains. Treatment allocation was the strongest independent predictor of improvement in physical HRQoL ({beta} = 0.492, p = 0.017) and pain intensity ({beta} = -0.512, p = 0.006). Conclusions: Improvements in IL-6 and hs-CRP were associated with reductions in pain intensity but not with improvements in HRQoL. Treatment allocation was the strongest predictor of clinical improvement, suggesting that mechanisms beyond systemic inflammation may contribute to the benefits of aerobic exercise in NSCLBP. Keywords: non-specific chronic low back pain; aerobic exercise; inflammation; interleukin-6; high-sensitivity C-reactive protein; pain intensity; health-related quality of life.

Background: Whether a patient's pain improved after emergency department (ED) treatment is read from the record to benchmark EDs, compare drugs, and label research outcomes. It is interpretable only if a post-treatment score is recorded, appropriately timed, and chosen by a fixed rule; its stability across these choices is unknown. Methods: Retrospective measurement study of adult headache visits in a de-identified ED database (MIMIC-IV-ED, 2011-2019). Among treated visits, we quantified reassessment completeness by time window, estimated meaningful relief (a reduction of at least 2 points) under score-selection rules and missing-data assumptions, tested whether reassessment was predictable at treatment, and compared headache with other painful presentations. Results: Among 19,501 visits (15,273 patients), 13,682 (70.2%) were treated. A post-treatment pain score appeared at any time for 77.1% (95% CI, 76.4 to 77.8), but within 2 hours of the analgesic for only 47.9% and within 1 hour for 27.5%. Meaningful relief was 66.9% using the first post-treatment score but 81.0% and 83.4% using the last or lowest score; it was 67.5% under inverse-probability weighting and could be bounded only between 51.8% and 74.4%. Whether a score was recorded was weakly predictable at treatment (area under the curve, 0.566) and unrelated to baseline pain. Completeness was similar across headache strata and comparator painful presentations. In an independent ED (MC-MED, a different EHR), the score-selection effect replicated: relief rose from 71.1% (first) to 80.6% (last) and 83.4% (lowest). Conclusions: Documented pain relief after ED headache treatment was not a stable outcome: it varied with the reassessment window and score-selection rule, was not point-identified for unreassessed patients, and behaved like other painful ED presentations. Programs and research that use documented relief should prespecify the reassessment window, score-selection rule, completeness denominator, and a missing-data range, and favor protocol-timed reassessment.

Cannabidiol (CBD) is a non-psychoactive component of cannabis that has been studied as a potential therapy for chronic pain. CBD attenuates behavioral hypersensitivities in models of neuropathic pain, and promotes production of bioactive lipids (e.g., anandamide), altering lipid signaling. However, a lack of understanding of the mechanisms underlying the therapeutic effects of CBD has hindered development and application of CBD to mechanism-based therapies for pain in people. We asked whether the analgesics effects of CBD were dependent upon the enzyme NAPE-PLD. We used a mouse model of chemotherapy-induced peripheral neuropathy (CIPN) to evaluate the acute and chronic antinociceptive effects of CBD and investigate its mechanisms. Pharmacological specificity was tested with antagonists targeting CB1, CB2, PPAR{gamma}, and PPAR receptors. Mechanisms were further examined using NAPE-PLD and GPR55 knockout mice. We also assessed repeated CBD dosing during both the development and maintenance of paclitaxel-induced CIPN in wild-type, GPR55 KO, and NAPE-PLD KO mice. CBD suppressed paclitaxel-induced behavioral hypersensitivities; these effects were attenuated by a PPAR and PPAR{gamma} antagonists, but not CB1 or CB2 antagonists. CBD reduced both the development and maintenance of neuropathic nociception in a model CIPN in wild-type mice, but these effects were absent in NAPE-PLD KO mice. By contrast, anti-allodynic efficacy of CBD was fully preserved in GPR55 KO mice. Pharmacological blockade of the PPAR receptor and genetic deletion of NAPE-PLD abolished the antinociceptive effects of CBD in a model of CIPN, suggesting a pivotal role for NAPE-PLD and PPAR receptors in CBD-mediated analgesia in chemotherapy-induced neuropathic pain.

Background Retaining repeat blood donors is essential for maintaining a safe and sustainable blood supply. While pain during venepuncture has been linked to lower donor return, the influence of donor-perceived needle quality on future donation remains unclear, particularly in low- and middle-income countries. This study examined whether perceived needle quality was associated with willingness to donate again among blood donors in Bangladesh. Methods We conducted a cross-sectional analytical study among 100 consecutively recruited whole-blood donors from participating blood donation centres in Bangladesh. Participants completed a structured questionnaire assessing demographic characteristics, donation history, procedural pain using a 10-point Visual Analogue Scale (VAS), pre-donation fear, perceived needle quality, vasovagal symptoms, overall satisfaction, and willingness to donate again on a five-point ordinal scale. Univariable ordinal logistic regression was used for variable screening, followed by multivariable proportional-odds ordinal logistic regression with purposeful variable selection. Statistical significance was set at p < 0.05. Results The mean donor age was 35.8 +/- 11.8 years, and 88% of participants were male. High procedural pain (VAS >= 4) was reported by 73% of donors, whereas 48% expressed high willingness to donate again. After adjustment, procedural pain was the only independent predictor of future donation intention. Each one-point increase in pain score reduced the odds of greater willingness to donate again by 54% (adjusted OR 0.46, 95% CI 0.37-0.57; p < 0.001). Donor-perceived needle quality was not associated with willingness to donate again (adjusted OR 1.09, 95% CI 0.47-2.56; p = 0.840) and showed no association with procedural pain. Conclusions Procedural pain, rather than donor-perceived needle quality, was the principal determinant of willingness to donate again. Interventions that improve donor comfort and minimise venepuncture pain may strengthen donor retention. Larger prospective studies using actual donor return behaviour are warranted.