Pain Subgroups Research Articles

Temporal summation of pain in sickle cell disease: comparison of adolescents and young adults with chronic vs. infrequent pain.

This study examined the role of central sensitization in the experience of pain among adolescents and young adults with the most severe genotypes of sickle cell disease (SCD). We hypothesized that adolescents and young adults with chronic SCD pain would demonstrate a higher perceptual response to repeated stimulation of identical intensity (i.e., temporal summation of pain, TSP) compared to counterparts with infrequent pain. We also examined psychological risk factors that can impact pain sensitivity. Patients ages 12-21 years, diagnosed with SCD type Hb SS or Hb S Beta0Thalasemia, who reported infrequent pain (≤2 pain days/month; n = 25) or met AAPT criteria for chronic SCD pain (n = 25) were enrolled. Patients were age- and sex-matched, with similar proportions receiving chronic blood transfusion and hydroxyurea. Patients completed static quantitative sensory testing (QST) and dynamic TSP testing to assess pain sensitivity. Patients and a caregiver completed demographic and psychological measures (depression, anxiety, pain interference, pain catastrophizing). Simple slope analysis revealed differentially elevated heat TSP among adolescents and young adults with chronic SCD pain (b = 3.14, p = .002) but not those with infrequent pain (b = 0.45, p = .61). Faster habituation was further observed for those with chronic compared to infrequent pain. Adolescents and young adults with chronic pain reported more frequent depression, anxiety, and pain interference symptoms; however, psychological symptoms and pain catastrophizing were not associated with QST or TSP (ps >.17). Current results demonstrate that a well-established, prognostic, QST risk marker (i.e., TSP) may distinguish chronic from infrequent pain subgroups of adolescents and young adults with SCD.

A comparative analysis of lumbar paraspinal muscle morphology between two movement system impairment subgroups of chronic nonspecific low back pain

BackgroundBased on the kinesiopathologic model, the Movement System Impairment (MSI) classification of LBP has shown that repetitive movements could contribute to pathoanatomic tissue changes. However, these changes have not been evaluated in different MSI classification subgroups of patients with LBP. ObjectiveThis study compared the grades of fatty infiltration as one of the muscle's pathologic changes in the lower lumbar paraspinal and psoas muscles between the two subgroups of patients diagnosed with MSI syndromes having opposite movement direction impairments. DesignObservational cross-sectional study. MethodForty-five participants with chronic LBP were enrolled in the study, with 23 patients in the lumbar flexion-rotation (FlexRot) subgroup and 22 in the lumbar extension-rotation (ExtRot) subgroup of MSI. Magnetic resonance imaging (MRI) and the Goutallier Classification System (GCS) were used for fatty grading of lumbar paraspinal and psoas muscles. After the reliability of this grading scale was evaluated, the results were compared between the two subgroups. ResultsThe Mann–Whitney U Test showed significantly higher fat infiltration of lower lumbar multifidus and erector spinae muscles in the lumbar ExtRot subgroup, with no significant difference between the two subgroups in terms of psoas muscles (P ≤ 0.05). Inter-rater reliability of GCS was acceptable to excellent, and intra-rater reliability was good to excellent. ConclusionThe fatty infiltration grade of lumbar paraspinal muscles in L4-L5 and L5-S1 levels are significantly different between the two LBP subgroups of MSI that have two opposite movement direction impairments. The lumbar paraspinal muscles, which contribute to extension, have a higher grade of fat in the ExtRot subgroup, whose symptoms are aggravated by lumbar extension.

An exploratory data-driven approach to classify subgroups of patients with temporomandibular disorders based on pain mechanisms

Temporomandibular disorders (TMDs) are a common musculoskeletal condition, presenting treatment challenges due to their non-specific nature. Categorizing patients with TMDs into clusters based on neurobiological pain mechanisms could provide a promising approach to facilitate targeted treatments. This observational study (1) used a network analysis (NA) to explore the complexity of TMDs by investigating relationships among biopsychosocial variables, and (2) validated potential TMD subgroups based on mechanism-specific pain categories. One hundred and two patients with TMD were included. Biopsychosocial variables covered: general health, psychosocial features, TMD pain, and TMD characteristics. A NA evaluated the associations between variables and determined the role of each feature within the network. Hierarchical clustering was used to identify TMD subgroups. The NA revealed significant correlations primarily within the same feature domains, indicating a strong interplay between symptoms and psychological factors. Cluster analysis identified two subgroups driven by nociceptive and nociplastic pain mechanisms; the nociplastic group exhibited higher levels of anxiety, depression, pain catastrophization, central sensitization, pain duration, and more pain locations, along with poorer sleep quality, quality of life, and health status. In contrast, the nociceptive group exhibited restricted maximal mouth opening (MMO), heightened pain during TMJ palpation and mouth opening, and a greater positive response to manual therapy. Across all features, psychological factors, pain locations, and MMO primarily contributed to the separation of subgroups. By adopting a data-driven approach, these results support the significant role of considering the neurobiological basis of pain to improve patient classification. This knowledge may facilitate clinical reasoning and personalized treatments. PerspectiveThis study used a network analysis to explore the complex biopsychosocial interactions present in people with TMDs, identifying important variables such as the Central Sensitization Inventory and pain-free maximal mouth opening. The findings distinguish potential nociceptive and nociplastic pain subgroups, offering important insights for targeted therapeutic strategies.

Botulinum Toxin A for the management of temporomandibular myofascial pain - a cohort study

Myofascial pain represents the largest subgroup of TMD (Temporomandibular Disorders), which accounts for a common cause of non-dental orofacial pain. The management of TMD is complex, due to the chronic nature of the condition, alongside acute episodes presenting to the clinician. A fundamental part of TMD management is consideration of the bio-psycho-social element in the aetiology of TMD. First-line treatment of myofascial TMD includes; early diagnosis, explanation and education and conservative self-care measures. More recently, Botulinum Toxin A (BTX-A) is being used increasingly as an adjunct to conservative management of muskulo-skeletal pain disorders, due to its muscle-relaxant and analgesic properties. However, the scientific evidence regarding this is conflicting and it has been suggested that there is insufficient evidence to support the efficacy of BTX-A. A mixed method analysis of a TMD-myofascial pain cohort who underwent BTX-A injections to assess the effectiveness of masseteric BTX-A was carried out. 149 patients completed one round of masseteric BTX-A treatment, of whom 61 completed an additional round of BTX-A. In total, 398 masseter muscles were injected. The average VAS pain score pre-operatively was 8/10, compared with a postoperative mean score of 3/10 at 6 weeks after treatment. The mean percentage reduction in pain was 50%. Pain scores were classified as mild (≤4) , moderate (≤7) or severe (≥8). Pain scores and quality of life scores were found to improve considerably more in the severe pain group in comparison to the mild group. Complete resolution of symptoms was reported in 21% of patients (n=31). The treatment significantly improved patients’ reported pain and quality of life scores, highlighting key beneficial effects for the myofascial pain subgroup of TMD.

The effects of connective tissue massage and classical massage on pain, lumbar mobility, function, disability, and well-being in chronic low back pain: A three-arm randomized controlled trial

BackgroundChronic low back pain (CLBP) is a common musculoskeletal disorder. Effect of massage in the management of CLBP has been documented, but it is not clear which massage regimen is more effective. This study was carried out to compare the effect of connective tissue massage and classical massage on pain, lumbar mobility, function, disability, and well-being among patients with CLBP. MethodsThe study included 30 participants who were randomly assigned to one of three intervention groups: the connective tissue massage group (CTMG; n = 10), the classical massage group (CMG; n = 10), and a standard physiotherapy/control group (CG; n = 10). The interventions were administered three times a week for four consecutive weeks. Assessments were conducted at baseline and at the end of the fourth week. Pain severity (Visual Analog Scale), lumbar mobility (Modified Schober Test), function (Back Pain Functional Scale), disability (Roland Morris Disability Questionnaire), and well-being (Short Form-36/SF-36) was evaluated. ResultsAll groups exhibited improvements in pain, lumbar mobility, function, and disability after 4 weeks (p < 0.05). The CMG showed enhancements in physical function, bodily pain, role physical, and role emotional subgroups of SF-36. The CTMG demonstrated improvements in all subgroups of SF-36 except general health (p < 0.05), while the CG only improved in the physical function subgroup (p < 0.05). A 2-way repeated measures ANOVA revealed a significant group-time interaction for MST (p = 0.04), Bodily Pain (p = 0.025) and Role Physical (p = 0.015). ConclusionsThe findings obtained from this study showed that CTMG was superior to CMG and CG in increasing lumbar mobility, and both massage applications were superior to the CG in increasing the well-being.

Pain Management Treatments and Opioid Use Disorder Risk in Medicaid Patients

IntroductionPeople with chronic pain are at increased risk of opioid-misuse. Less is known about the unique risk conferred by each pain management treatment, as treatments are typically implemented together, confounding their independent effects. This study estimated the extent to which pain management treatments were associated with risk of opioid use disorder (OUD) for those with chronic pain, controlling for baseline demographic and clinical confounding variables and holding other pain management treatments at their observed levels. MethodsData were analyzed in 2024 from two chronic pain subgroups within a cohort of non-pregnant Medicaid patients aged 35-64 years, 2016-2019, from 25 states: those with 1) chronic pain and physical disability (CPPD) (N=6,133) or 2) chronic pain without disability (CP) (N=67,438). Nine pain management treatments were considered: prescription opioid i) dose and ii) duration; iii) number of opioid prescribers; opioid co-prescription with iv) benzo- diazepines, v) muscle relaxants, and vi) gabapentinoids; vii) non-opioid pain prescription, viii) physical therapy, and ix) other pain treatment modality. The outcome was OUD risk. ResultsHaving opioids co-prescribed with gabapentin or benzodiazepine was statistically significantly associated with a 37-45% increased OUD risk for the CP subgroup. Opioid dose and duration also were significantly associated with increased OUD risk in this subgroup. Physical therapy was significantly associated with an 18% decreased risk of OUD in the CP subgroup. ConclusionsCo-prescription of opioids with either gabapentin or benzodiazepines may substantially increase OUD risk. More positively, physical therapy may be a relatively accessible and safe pain management strategy.

Increased Thalamocortical Functional Connectivity on Discontinuation of Treatment in Painful Diabetic Peripheral Neuropathy.

Altered functional connectivity has been demonstrated in key brain regions involved in pain processing in painful diabetic peripheral neuropathy (Painful-DPN). However, the impact of neuropathic pain treatment on functional connectivity has not been investigated. Sixteen participants underwent resting state functional MRI (rs-fMRI) when optimally treated for neuropathic pain during their involvement in the OPTION-DM trial and 1-week following withdrawal of treatment. On discontinuation of pain treatment, there was a rise in functional connectivity between the left thalamus and primary somatosensory cortex (S1) and the left thalamus and insular cortex, key brain regions that are involved in cerebral processing of pain. The changes in functional connectivity between scans also correlated with measures of pain (baseline pain severity and neuropathy pain symptom inventory). Moreover, when participants were stratified into higher and lower than average baseline pain sub-groups, the change in thalamic-S1 cortical functional connectivity between scans was significantly greater in those with high baseline pain compared with the lower baseline pain group. This study shows that thalamo-cortical functional connectivity has the potential to act as an objective biomarker for neuropathic pain in diabetes for use in clinical pain trials.

Association of night-time sleep and daytime napping with painful temporomandibular disorder.

Painful temporomandibular disorder (TMD) is the common cause of chronic oro-facial pain, which may interfere with sleep. Previous studies have documented an association between sleep and TMD. This study aimed to further explore the association of night-time sleep and daytime napping with painful TMD. A total of 419 patients (aged 31.88 ± 11.54 years with women forming 85.4%) from a TMD/Orofacial Pain center were enrolled. Patients' sleep conditions were evaluated with the Pittsburgh Sleep Quality Index (PSQI) questionnaire, and information on night-time sleep duration, napping duration and napping frequency was interviewed. TMD was diagnosed according to the Diagnostic Criteria for TMD protocol and stratified into myalgia (muscle pain), arthralgia (joint pain) and combined (muscle and joint pain) subgroups. The severity of TMD was measured with the Fonseca Anamnestic Index (FAI) questionnaire. Restricted cubic spline (RCS) regression models were established to explore relationships between sleep and painful TMD subgroups. Patients with poor sleep quality (PSQI≥6) had higher FAI scores (median 60, p < .001) and higher proportions of painful TMDs. The myalgia subgroup had higher PSQI scores (median 8, p < .001) than the arthralgia subgroup. The RCS models indicated a non-linear relationship between night-time sleep duration and myalgia (p < .001), which was not observed in arthralgia. However, there were no significant findings concerning napping and painful TMD subgroups. This study found that the association between sleep and TMD is mainly related to painful TMD conditions, which are associated with night-time sleep duration.

Role of End Plate Changes and Paraspinal Muscle Pathology in Lower Back Pain: A Narrative Review.

Degenerative changes of the lumbar intervertebral disc are the most significant causes of enduring lower back pain. The possibility of the diagnosis is limited in people with this low back pain. Therefore, it is essential to identify the relevant back pain subgroups. The paraspinal muscles, that is, the muscles that attach to the spine, are necessary for the proper functioning of the spine and the body; insufficiency can result in back pain. Lower back pain disorders are strongly associated with altered function or structure of these paraspinal muscles, especially fibrosis and fatty infiltration. Modic changes are the bone marrow changes of the end plate in the vertebral body seen on MRI. These are strongly related to degeneration of the disc and are common in individuals with back pain symptoms. Articles were selected from Google Scholar using the terms 'Modic changes,' 'end plate changes,' 'paraspinal muscles,' and 'lower back pain. ' This article compiled different studies aiming to enhance the comprehension of biochemical processes resulting in the development of lumbar pain. Search using the keywords 'Modic changes,'' end plate changes lower back pain,' 'paraspinal muscles lower back pain,' and 'Modic changes lower back pain' on Google Scholar yielded 33000, 41000, 49400, and 17,800 results, and 958, 118, 890 and 560 results on Pubmed respectively.

Differential relationships between physical activity and pain phenotypes in individuals with spinal cord injury

Background Chronic pain affects 70% of individuals with spinal cord injury (SCI) and leads to declines in health and quality of life. Neuropathic and nociceptive pain are phenotypes derived from different mechanisms that contribute to pain perception. The objective of this research was to investigate differential pain responses to moderate-to-vigorous physical activity (MVPA) in two chronic pain phenotypes: neuropathic and nociceptive pain. Methods Community-based physical activity levels were collected for one week in 17 individuals with SCI using a wrist-worn accelerometer, and daily pain ratings were assessed and categorized by phenotype. Physical activity levels were summarized to calculate minutes of MVPA. Correlational analyses were conducted to compare relationships between pain intensity and MVPA across individual participants and between pain phenotype groups. Results The neuropathic pain group revealed significant negative correlation between MVPA and pain intensity. In the nociceptive pain group, there was no significant correlation between MVPA and pain intensity. Further analysis revealed two subgroups of positive (N = 4) and negative (N = 3) correlations between MVPA and pain intensity. Pain location differed between the subgroups of nociceptive pain. Individuals with negative correlation experienced neck and upper back pain, whereas individuals with positive correlation experienced unilateral upper extremity pain. Conclusion Differential relationships exist between pain phenotypes and MVPA in individuals with SCI. Pain location differed between the subgroups of nociceptive pain, which we presume may indicate the presence of nociplastic pain in some individuals. These results may contribute to the advancement of personalized pain management by targeting non-pharmacological interventions for specific pain phenotypes. Trial registration: ClinicalTrials.gov identifier: NCT05236933..

Prognosis of Pain After Stroke During Rehabilitation Depends on the Pain Quality.

Pain after a stroke interferes with daily life and the rehabilitation process. This study aimed to clarify the prognosis of pain in subgroups of patients with pain after a stroke using pain quality data. The study included 85 patients with pain after stroke undergoing exercise-based rehabilitation. Items of the Neuropathic Pain Symptom Inventory (NPSI) were used, and patients with pain after stroke were clustered according to their scores of NPSI. Other clinical assessments, such as physical and psychological conditions, were assessed by interviews and questionnaires, and then these were compared among subgroups in a cross-sectional analysis. Longitudinal pain intensity in each subgroup was recorded during 12weeks after the stroke and the patients' pain prognoses were compared between subgroups. Four distinct subgroups were clustered: cluster 1 (cold-evoked pain and tingling), cluster 2 (tingling only), cluster 3 (pressure-evoked pain), and cluster 4 (deep muscle pain with a squeezing and pressure sensation). The cross-sectional analysis showed varying clinical symptoms among the subgroups, with differences in the prevalence of joint pain, limited range of motion, somatosensory dysfunction, and allodynia. There were no significant differences in pain intensity at baseline among the subgroups. A longitudinal analysis showed divergent prognoses of pain intensity among the subgroups. The pain intensity in cluster 4 was significantly alleviated, which suggested that musculoskeletal pain could be reduced with conventional exercise-based rehabilitation. However, the pain intensity of patients in clusters 1 and 2 remained over 12weeks. The study classified patients into clinically meaningful subgroups using pain quality data and provided insight into their prognosis of pain. The findings could be useful for guiding personalized rehabilitation strategies for pain management. Assessment of pain quality in patients with pain after stroke leads to personalized rehabilitation for pain management.

Assessment of Spinal and Pelvic Kinematics Using Inertial Measurement Units in Clinical Subgroups of Persistent Non-Specific Low Back Pain.

Inertial measurement units (IMUs) offer a portable and quantitative solution for clinical movement analysis. However, their application in non-specific low back pain (NSLBP) remains underexplored. This study compared the spine and pelvis kinematics obtained from IMUs between individuals with and without NSLBP and across clinical subgroups of NSLBP. A total of 81 participants with NSLBP with flexion (FP; n = 38) and extension (EP; n = 43) motor control impairment and 26 controls (No-NSLBP) completed 10 repetitions of spine movements (flexion, extension, lateral flexion). IMUs were placed on the sacrum, fourth and second lumbar vertebrae, and seventh cervical vertebra to measure inclination at the pelvis, lower (LLx) and upper (ULx) lumbar spine, and lower cervical spine (LCx), respectively. At each location, the range of movement (ROM) was quantified as the range of IMU orientation in the primary plane of movement. The ROM was compared between NSLBP and No-NSLBP using unpaired t-tests and across FP-NSLBP, EP-NSLBP, and No-NSLBP subgroups using one-way ANOVA. Individuals with NSLBP exhibited a smaller ROM at the ULx (p = 0.005), LLx (p = 0.003) and LCx (p = 0.01) during forward flexion, smaller ROM at the LLx during extension (p = 0.03), and a smaller ROM at the pelvis during lateral flexion (p = 0.003). Those in the EP-NSLBP group had smaller ROM than those in the No-NSLBP group at LLx during forward flexion (Bonferroni-corrected p = 0.005), extension (p = 0.013), and lateral flexion (p = 0.038), and a smaller ROM at the pelvis during lateral flexion (p = 0.005). Those in the FP-NSLBP subgroup had smaller ROM than those in the No-NSLBP group at the ULx during forward flexion (p = 0.024). IMUs detected variations in kinematics at the trunk, lumbar spine, and pelvis among individuals with and without NSLBP and across clinical NSLBP subgroups during flexion, extension, and lateral flexion. These findings consistently point to reduced ROM in NSLBP. The identified subgroup differences highlight the potential of IMU for assessing spinal and pelvic kinematics in these clinically verified subgroups of NSLBP.

Lumbar spine and hip motion angles are associated with movement direction of pain in patients with low back pain

BACKGROUND: The evaluation and treatment of patients with low back pain (LBP) often involve categorization based on movement direction. However, it is not certain whether the lumbar spine and hip motion angles are associated with movement direction in individuals with LBP. OBJECTIVE: The purpose of this study was to verify whether the motion angles of the lumbar spine and hip joint are associated with the movement direction in individuals with LBP. METHODS: Participants were recruited as volunteers at the authors’ institutions. In this cross-sectional observational study, participants were divided into two groups: those without LBP and those with LBP. To measure lumbar spine and hip motion angles in clinical movement tests (trunk forward bending and prone hip extension), those with LBP were divided into a flexion LBP group and an extension LBP group. Wearable sensors were used to measure lumbar spine and hip motion angles. RESULTS: Participants with LBP had a greater hip motion angle in the early stages of movement than that of those without LBP; this was associated with the movement direction in which pain appeared. CONCLUSIONS: In individuals with LBP, the motion angles of the lumbar spine and hip joint are associated with the movement direction. Therefore, this pain subgroup and associated movement direction should be considered when evaluating and treating individuals with LBP.

The Rating of Perceived Exertion-Pediatric (RPE-P) Scale: Preliminary Validation.

Physical activity is critical to functional rehabilitation for youth with chronic pain, which may be especially true for those with co-occurring obesity. To facilitate the development of physical activity interventions for youth with chronic pain, the newly developed "Rating of Perceived Exertion-Pediatric" scale was modeled after the widely used pain numeric rating scale-11. This study is an initial evaluation of the scale in a sample of adolescents (n = 157, 13-17 years, 51% female) with four subgroups: (1) healthy controls (healthy weight/no pain); (2) chronic pain/healthy weight; (3) obese (no pain); (4) chronic pain/obese. Participants rated perceived exertion using the new scale and the Borg 6-20 Scale of Perceived Exertion while holding a three-minute yoga pose (Warrior II). In the whole sample, the Perceived Exertion-Pediatric scale showed good concurrent (p < 0.001), convergent (all ps < 0.05), discriminant (p = 0.431), and known-groups validity (all ps < 0.05). The chronic pain subgroup also showed good concurrent (p < 0.001), mixed convergent (ps < 0.001 to 0.315), and good discriminant validity (p = 0.607). Limitations include the restricted age range, lack of diversity, and lack of test-retest reliability. The RPE-P shows promise as an assessment tool for perceived exertion in adolescents with and without chronic pain.

Cluster Analysis Reveals Distinct Subgroups with Severe Pain in Sickle Cell Disease: A Cross-Sectional Study Using the Grndad Multi-Center Registry

Introduction: Sickle cell disease (SCD) affects millions worldwide and is characterized by episodic severe pain, impacting quality of life and leading to significant healthcare utilization. Yet, clinicians face significant challenges in treating pain in individuals with SCD due to heterogeneity in pain experiences and pain impact. Improved understanding of the clinical characteristics of individuals with SCD who are at risk for developing severe pain is necessary to better manage pain and develop novel and personalized pain interventions. The objectives of this study were to (1) identify distinct pain subgroups based on demographic and psychosocial characteristics and (2) evaluate the relationship between the subgroups and pain impact. Methods: We performed a hierarchical cluster analysis on a cross-sectional sample of adults living with SCD enrolled in the Global Research Network Data and Discovery (GRNDaD) registry who had completed the Adult Sickle Cell Quality of Life Measurement Information System (ASCQ-Me) surveys. Classification variables for clustering included SCD subtype (SS/Sβ 0-thalassemia [SCA] vs SC/Sβ +-thalassemia [variant]), sex, age, presence of chronic pain, frequency of SCD pain episodes, and social and emotional functioning. Results: There were 472 adult participants included in the analysis. The overall sample was 59% female with a median age of 33 (IQR 26-42 years). Five distinct subgroups were identified: Subgroup 1 (n=117, 100% SCA subtype, 100% female, median age 33, high chronic pain and pain episodes, and poor social and emotional functioning), Subgroup 2 (n=98, 100% variant subtype, 65% female, median age 34, high chronic pain and pain episodes, poor social and emotional functioning), Subgroup 3 (n=141, 100% SCA, 100% male, median age 30, moderate chronic pain, high pain episodes, and low-normal social and emotional functioning), Subgroup 4 (n=41, 100% variant, 54% female, median age 40, low chronic pain and pain episodes, normal social and emotional functioning), and Subgroup 5 (n=75, 100% SCA, 100% female, median age 34, no chronic pain, low pain episodes, and normal social and emotional functioning). All subgroups differed significantly (p&amp;lt;0.05) with respect to pain impact/interference, with Subgroups 1-3 demonstrating worse pain impact. Additionally, significant differences in hospitalization, education and income, total hemoglobin and fetal hemoglobin levels were noted between the subgroups. Hydroxyurea use was similar in the three clusters with SCA (subgroups 1 and 2). Conclusion: To our knowledge, this analysis represents the largest pain subgroup analysis in SCD. Subgroups with worse pain impact were characterized by poorer social and emotional functioning, implying that psychosocial factors are strongly associated with pain outcomes in individuals with SCD. Moreover, variations in pain impact based on sex and SCD subtype suggest these factors are associated with differences in pain outcomes. Additionally, we found that the presence of chronic pain is associated with higher pain impact, increased healthcare utilization, and more frequent pain episodes. The study should be interpreted with consideration of the following limitations: (1) cross-sectional design, which limits the ability to establish causality or directionality between the various associations, and (2) reliance on self-reported measures that may be subject to recall and reporting biases. Nevertheless, these findings highlight the heterogeneity in pain experiences and suggest that multimodal interventions may be critical in addressing the pain and psychosocial burden for individuals with SCD. Longitudinal studies are needed to further validate these findings and explore how pain profiles may change over time in individuals with SCD.

Perioperative Opioid Use and Dosage Trajectories Vary Depending on Pain Outcome Classification and Bodily Pain in Patients who Catastrophize About Their Pain: A Secondary Analysis of a Randomized Trial in Knee Arthroplasty

Opioid use and dosage following knee arthroplasty (KA) has not been reported for subgroups with persistent moderate pain versus rapidly improving mild pain, externally validated from prior work. We determined if opioid use and dosage varied for persons classified into these externally validated subgroups. A secondary purpose determined if bodily pain scores are associated with the outcome subgroup. This was a secondary analysis of a prospective no-effect randomized clinical trial conducted on 384 participants with pain catastrophizing and scheduled for KA. Data were collected preoperatively and at 2-, 6-, and 12-month following surgery. Two-piece latent class growth curve analyses applied previously validated pain outcomes to determine subgroup outcome trajectories for the proportion of opioid users and oral morphine equivalent (OME) dosages. Substantial trajectory separation was found for opioid use and OME. Specifically, the average OME dosage for the persistent moderate pain subgroup was more than double that for the other outcome subgroup. The average preoperative opioid daily OME dosage for 170 patients reporting opioid use was 24.94 (95% [confidence interval] CI = 20.52, 29.38). Bodily pain was consistently higher for the persistent moderate pain subgroup compared to the other subgroup. Outcome subgroups in patients with pain catastrophizing demonstrated substantial differences in opioid use and dosage and were predicted by high pain catastrophizing, more bodily pain, and changes in bodily pain over time. The persistent moderate pain subgroup is at greater risk of opioid use and greater opioid dosages and should be targeted for preoperative screening and interventions to reduce opioid use and potential opioid misuse. PerspectiveMore frequent and higher opioid dosage following KA was found for the persistent moderate pain subgroup compared to the other subgroup. Patients with persistent pain had worse catastrophizing, contralateral and ipsilateral lower extremity pain, low back pain, and whole body pain compared to the rapidly improving mild pain subgroup.

Comparisons of lumbosacral kinematics among non-specific chronic low back pain subgroups and healthy during prolonged sitting: A cross-sectional observational study

BackgroundThe literature has suggested a variety of postural changes of the spine that possibly contribute to the increase in back pain during sitting in persons with non-specific chronic low back pain (NS-CLBP). However, the heterogeneity of NS-CLBP persons has made the ability to attribute pain increase to a particular sitting posture very difficult. Therefore, the purpose of this study was to compare lumbosacral kinematics and their roles in pain increase among homogenous NS-CLBP subgroups and healthy controls over a 1-h sitting period. MethodsTwenty NS-CLBP subjects with motor control impairment [10 classified as having flexion pattern (FP) disorder, and 10 with active extension pattern (AEP) disorder], and 10 healthy controls participated in the study. Subjects underwent a 1-h sitting protocol on a standard office chair. Lumbosacral postures including sacral tilt, third lumbar vertebrae (L3) position, and relative lower lumbar angle were recorded using two-dimensional inclinometers over the 1-h period. Perceived back-pain intensity was measured using a visual analog scale every 10 min throughout the sitting period. ResultsAll study groups (FP, AEP and healthy controls) significantly differed from each other in the measured lumbosacral kinematics at the beginning as well as at the end of the sitting period (p ≤ 0.05). Only the NS-CLBP subgroups showed significant changes in the lumbosacral kinematics across the 1-h sitting period (p < 0.01), and that the directions of change occurred toward end spinal postures (lumbar kyphosis for FP subgroup and lumbar lordosis for the AEP subgroup). In addition, both NS-CLBP subgroups reported a similarly significant increase in pain through mid-sitting (p < 0.001). However, after mid-sitting, the AEP subgroup reported much less increase in pain level that was accompanied by a significant decrease in the lumbar lordotic postures (p = 0.001) compared to FP subgroup. ConclusionThe present study's findings suggest that each NS-CLBP subgroup presented with differently inherent sitting postures. These inherently dysfunctional postures coupled with the directional changes in the lumbosacral kinematics toward the extreme ranges across the 1-h sitting period, might explain the significant increase in pain among subgroups.

Hospital admission is associated with disability and late musculoskeletal pain in individuals with long COVID.

The acute clinical repercussions of SARS-CoV-2 infection have been widely studied. However, the possible late repercussions of long COVID have not yet been well defined in the literature. To identify the presence of pain and musculoskeletal disability in patients with Long COVID and also to identify predictive factors for pain intensity in this population. In this cross-sectional and retrospective observational study individuals with Long COVID symptoms were included. It was collected musculoskeletal disability measures, data from patient-related outcome measures and variables from a COVID-19 outpatient service database. Associations and sub-group analyses were performed considering the variables pain, disability and hospitalization. Linear regression was performed to identify predictive factors for pain intensity in Long COVID patients. We evaluated 195 patients and most of them (57%) presented musculoskeletal pain in one area of the body. Pain sub-group presented worse disability indices and worse clinical course during hospitalization. Hospitalized patients presented worse disability indices comparing to non-hospitalized. Significant correlations were found between pain and days of non-invasive oxygen support (r = 0.21; p = 0.003); days in intensive care unit (r = 0.22; p = 0.002) and days in invasive mechanical ventilation (r = 0.35; p = 0.001). Hospitalized individuals showed a higher chance of presenting late musculoskeletal pain (OR = 1.42: 95%CI 1.09-2.04). Days in intensive care unit (β = 0,234: P = 0,001) and days in invasive mechanical ventilation (β = 0.764: P = 0.001) were predictors of pain intensity [F(2,192) = 18.559; R2 = 0.231; p = 0.001]. Individuals with Long COVID presented musculoskeletal pain and disability. Hospitalized patients showed a greater chance of having musculoskeletal pain. Days in intensive care unit and days in invasive mechanical ventilation were predictors of late musculoskeletal pain intensity.

Increasing frequency of dyspnea among patients referred for cardiac stress testing.

To assess the frequency, change in prevalence, and prognostic significance of dyspnea among contemporary patients referred for cardiac stress testing. We evaluated the prevalence of dyspnea and its relationship to all-cause mortality among 33,564 patients undergoing stress/rest SPECT-MPI between January 1, 2002 and December 31, 2017. Dyspnea was assessed as a single-item question. Patients were divided into three temporal groups. The overall prevalence of dyspnea in our cohort was 30.2%. However, there was a stepwise increase in the temporal prevalence of dyspnea, which was present in 25.6% of patients studied between 2002 and 2006, 30.5% of patients studied between 2007 and 2011, and 38.7% of patients studied between 2012 and 2017. There was a temporal increase in the prevalence of dyspnea in each age, symptom, and risk factor subgroup. The adjusted hazard ratio for mortality was higher among patients with dyspnea vs those without dyspnea both among all patients, and within each chest pain subgroup. Dyspnea has become increasingly prevalent among patients referred for cardiac stress testing and is now present among nearly two-fifths of contemporary cohorts referred for stress-rest SPECT-MPI. Prospective study is needed to standardize the assessment of dyspnea and evaluate the reasons for its increasing prevalence.

Relationships between trunk muscle activation and thoraco-lumbar kinematics in non-specific chronic low back pain subgroups during a forward bending task

BackgroundTrunk muscle activity and thoraco-lumbar kinematics can discriminate between non-specific chronic low back pain (NSCLBP) subgroups and healthy controls. However, research commonly focuses on lumbar kinematics, with limited understanding of relationships between kinematics and muscle activity across clinical subgroups. Similarly, the thoracic spine, whilst intuitively associated with NSCLBP, has received less attention and potential relationships between spinal regions and muscle activity requires exploration. Research questionIs there a relationship between trunk muscle activation and regional thoracic and lumbar kinematics in NSCLBP subgroups during a forward bending task? MethodsObservational, case-control study. Fifty subgrouped NSCLBP motor control impairment participants (27 Flexion Pattern (FP-MCI), 23 Active Extension Pattern (AEP-MCI)) and 28 pain-free controls were evaluated using 3D motion analysis (Vicon™) and surface electromyography during a forward bending and return to upright task. Mean sagittal angles for the upper-thoracic (UTx), lower-thoracic (LTx), upper-lumbar (ULx) and lower-lumbar (LLx) regions were compared with normalised (% sub-maximal voluntary contraction) mean amplitude electromyography of bilateral transversus abdominis/internal oblique, external oblique, superficial lumbar multifidus and erector spinae (longissimus thoracis) muscles between groups. Pearson correlations were computed to assess relationships (significance p < 0.01). ResultsAEP-MCI individuals demonstrated statistically significant relationships between superficial lumbar multifidus and ULx and LLx kinematics (−.812 to.659). FP-MCI individuals exhibited statistically significant relationships between erector spinae and superficial lumbar multifidus and LLx and LTx kinematics (−.686 to.664) in both task phases, and between external oblique and LTx during forward bending) (−.459 to.572). Correlations were moderate to strong for all significant relationships (−.812 to .664). SignificanceRelationships between muscle activity and regional spinal kinematics varied between NSCLBP subgroups, suggesting that those with flexion- or extension-related LBP adopt different motor control strategies when performing a bending task. As effectively mechanical biomarkers, these findings may inform treatment by improving understanding of varied motor strategies in subgroups.