Pain Subgroups Research Articles

Recovery of the lumbopelvic movement and muscle recruitment patterns using motor control exercise program in people with chronic nonspecific low back pain: A prospective study.

This study aims to investigate the dysfunction and recovery of the lumbopelvic movement and motor control of people with chronic nonspecific low back pain after a structured rehabilitation which emphasizes on re-education and training of movement and motor control. The lumbopelvic movement and motor control pattern of 30 adults (15 with chronic low back pain, 15 healthy controls) were assessed using 3D motion and electromyographic analysis during the repeated forward bending test, in additional to the clinical outcome measures. Regional kinematics and muscle recruitment pattern of the symptomatic group was analysed before and after the 6-week rehabilitation, and compared to healthy controls. Significant improvement in back pain, functional capacity and self-efficacy of the symptomatic group was found after the rehabilitation. Patients with chronic nonspecific low back pain were capable to recover to a comparable level of the healthy controls in terms of their lumbopelvic movement and motor control pattern upon completion of a 6-week rehabilitation program, despite their dysfunction displayed at baseline. Phase specific motor control reorganization in which more profound and positive changes shown during the flexion phase. Our findings indicate that the recovery of the movement and motor control pattern in patients with chronic low back pain achieved to a comparable level of the healthy able-bodies. The improvement of both the physical outcome measures suggest that specific rehabilitation program which emphasizes on optimizing motor control during movements would help promoting the functional recovery of this specific low back pain subgroup.

Characterisation of motor cortex organisation in patients with different presentations of persistent low back pain.

Persistence of low back pain is thought to be associated with different underlying pain mechanisms, including ongoing nociceptive input and central sensitisation. We hypothesised that primary motor cortex (M1) representations of back muscles (a measure of motor system adaptation) would differ between pain mechanisms, with more consistent observations in individuals presumed to have an ongoing contribution of nociceptive input consistently related to movement/posture. We tested 28 participants with low back pain sub-grouped by the presumed underlying pain mechanisms: nociceptive pain, nociplastic pain and a mixed group with features consistent with both. Transcranial magnetic stimulation was used to study M1 organisation of back muscles. M1 maps of multifidus (deep and superficial) and longissimus erector spinae were recorded with fine-wire electromyography and thoracic erector spinae with surface electromyography. The nociplastic pain group had greater variability in M1 map location (centre of gravity) than other groups (p < .01), which may suggest less consistency, and perhaps relevance, of motor cortex adaptation for that group. The mixed group had greater overlap of M1 representations between deep/superficial muscles than nociceptive pain (deep multifidus/longissimus: p = .001, deep multifidus/thoracic erector spinae: p = .008) and nociplastic pain (deep multifidus/longissimus: p = .02, deep multifidus/thoracic erector spinae: p = .02) groups. This study provides preliminary evidence of differences in M1 organisation in subgroups of low back pain classified by likely underlying pain mechanisms. Despite the sample size, differences in cortical re-organisation between subgroups were detected. Differences in M1 organisation in subgroups of low back pain supports tailoring of treatment based on pain mechanism and motor adaptation.

An Empirical Classification of Chronic Pain Subgroups in Pediatric Sickle Cell Disease: A Cluster-Analytic Approach

Introduction: Youth with sickle cell disease (SCD) and chronic pain are a heterogeneous group with variability in their daily pain experience and physical and psychosocial functioning. We aimed to 1) empirically derive chronic pain subgroups based on sensory pain characteristics using cluster analysis within a sample of youth with chronic SCD pain, and 2) investigate derived subgroups for differences in sociodemographics, clinical characteristics, and psychosocial and functional outcomes. We hypothesized that chronic SCD pain subgroups with higher sensory pain experiences would be associated with poorer functional and psychosocial outcomes.Methods: Children and adolescents receiving care at comprehensive SCD clinics at three tertiary care locations within a southeast children's hospital were included if they were aged 10-18 years, any SCD genotype, reported chronic pain (i.e., pain on most days per month for a duration of at least 3 months), and had English fluency. Youth were excluded if they had comorbid medical conditions typically associated with pain but unrelated to SCD or had significant cognitive or developmental limitations that would interfere with study procedures. Patients completed a battery of patient-reported outcomes including pain characteristics (i.e., intensity, frequency, and the Adolescent Pediatric Pain Tool to assess number of pain locations and pain quality descriptors), PROMIS Pediatric Short Forms for pain interference, anxiety, and depressive symptoms, the Adolescent Sleep Wake Scale for sleep quality, and the Pain Catastrophizing Scale. Clinical characteristics and healthcare utilization outcomes were abstracted from electronic medical records including number of inpatient admissions for pain and emergency department visits for pain in the prior 12 months.Chronic SCD pain subgroups were based on sensory pain characteristics including pain intensity ratings, pain frequency, number of body sites affected by pain, and pain quality descriptors. Hierarchical cluster analysis informed the number of clusters at the patient level. K-means cluster analysis was used to assign patients to clusters once the number of clusters was established. Clusters were compared on sociodemographics, clinical characteristics, healthcare utilization, and child psychosocial and functional outcomes.Results: Youth (n=62) were on average (M) 13.9 years old (SD=2.5), 56% female, 95% Black or African American, and 85% Non-Hispanic/Latinx. Most (75%) had HbSS or HbSβ 0 and 67% were prescribed hydroxyurea. Hierarchical cluster analysis and k-means clustering supported a 2-cluster solution (see Figure 1). Cluster 1 (n=35; Frequent, Moderate Pain) was distinguished by significantly lower scores on worst pain intensity (M=6.4, SD=0.4), lower number of pain days per month (M=12.1, SD=2.8), fewer number of body sites affected by pain (M=8.9, SD=0.9), and lower pain quality ratings (M=15.9, SD=1.3). Cluster 2 (n=27; Almost Daily, High Pain) represented patients who reported high ratings of worst pain intensity (M=8.2, SD=0.3), daily to almost daily pain (M=20.3, SD=1.7), higher number of body sties affected by pain (M=12.5, SD=1.5), and higher ratings of pain quality (M=40.8, SD=1.9) (all p's <.05). There were no differences between chronic SCD pain subgroups by sociodemographics (e.g., age, sex, family income), clinical characteristics (e.g., genotype, history of avascular necrosis, disease-modifying treatments, prescribed long-acting opioids, neuropathic medications, or antidepressants), or healthcare utilization. Patients in the Almost Daily High Pain subgroup reported significantly higher pain interference, depressive symptoms, and pain catastrophizing compared to patients in the Frequent, Moderate Pain subgroup (see Table 1). There were no differences between subgroups on anxiety or sleep quality.Conclusions: Two subgroups of chronic SCD pain were identified based on pain, psychosocial, and functional outcomes. Beyond sensory pain characteristics, pain interference, depressive symptoms, and pain catastrophizing were the only variables that best differentiated the chronic SCD pain subgroups. These empirically derived subgroups are comparable to other non-SCD chronic pain subgroups in pediatrics and adults. Identifying homogenous chronic SCD pain subtypes can inform tailored assessment and management of chronic pain. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Musculoskeletal Features in Adults With X-linked Hypophosphatemia: An Analysis of Clinical Trial and Survey Data.

ContextPatients with X-linked hypophosphatemia (XLH) experience multiple musculoskeletal manifestations throughout adulthood.ObjectiveTo describe the burden of musculoskeletal features and associated surgeries across the lifespan of adults with XLH.MethodsThree groups of adults were analyzed: subjects of a clinical trial, participants in an online survey, and a subgroup of the online survey participants considered comparable to the clinical trial subjects (according to Brief Pain Inventory worst pain scores of ≥ 4). In each group, the adults were categorized by age: 18-29, 30-39, 40-49, 50-59, and ≥ 60 years. Rates of 5 prespecified musculoskeletal features and associated surgeries were investigated across these age bands for the 3 groups.ResultsData from 336 adults were analyzed. In all 3 groups, 43% to 47% had a history of fracture, with the proportions increasing with age. The overall prevalence of osteoarthritis was > 50% in all 3 groups, with a rate of 23% to 37% in the 18- to 29-year-old group, and increasing with age. Similar patterns were observed for osteophytes and enthesopathy. Hip and knee arthroplasty was reported even in adults in their 30s. Spinal stenosis was present at a low prevalence, increasing with age. The proportion of adults with ≥ 2 musculoskeletal features was 59.1%, 55.0%, and 61.3% in the clinical trial group, survey group, and survey pain subgroup, respectively.ConclusionThis analysis confirmed high rates of multiple musculoskeletal features beginning as early as age 20 years among adults with XLH and gradually accumulating with age.

Kinematic and Coordination Variability in Individuals With Acute and Chronic Patellofemoral Pain.

Altered gait variability occurs in those with patellofemoral pain and may be relevant to pain progression. We examined gait kinematic and coordination variability between individuals with acute and chronic patellofemoral pain and healthy controls. Eighty-three patellofemoral pain runners (37 men and 46 women) and 142 healthy controls (52 men and 90 women) ran on a treadmill while 3-dimensional lower limb kinematic data were collected. Patellofemoral pain runners were split into acute (n = 22) and chronic (n = 61) subgroups based on pain duration (< and ≥3mo, respectively). Approximate entropy assessed continuous hip, knee, and ankle kinematic variability. Vector coding calculated coordination variability for select joint couplings. Variability measures were compared between groups using 1-way analysis of variance and post hoc comparisons with Cohen d effect sizes. The chronic patellofemoral pain subgroup displayed higher frontal plane knee kinematic variability compared with controls (P = .0004, d = 0.550). No statistically significant effects for any coordination variability couplings were identified. Minimal differences in gait variability were detected between those with acute and chronic patellofemoral pain and healthy controls.

Classification of Geriatric Low Back Pain Based on Hip Characteristics With a 12-Month Longitudinal Exploration of Clinical Outcomes: Findings From Delaware Spine Studies.

The purpose of this study is to identify geriatric chronic low back pain (LBP) subgroups based on the presence of potentially modifiable hip impairments, using Latent Variable Mixture Modeling (LVMM), and to examine the prospective relationship between these subgroups and key outcomes over time. Baseline, 3-month, 6-month, and 12-month data were collected from a prospective cohort of 250 community-dwelling older adults with chronic LBP. Comprehensive hip (symptoms, strength, range of motion, and flexibility), LBP (intensity and disability), and mobility function (gait speed and 6-Minute Walk Test) examinations were performed at each timepoint. Baseline hip measures were included in LVMM; observed classes/subgroups were compared longitudinally on LBP and mobility function outcomes using mixed models. Regarding LVMM, a model with 3 classes/subgroup fit best. Broadly speaking, subgroups were differentiated best by hip strength and symptom presence: subgroup 1 = strong and nonsymptomatic, subgroup 2 = weak and nonsymptomatic, and subgroup 3 = weak and symptomatic (WS). Regarding longitudinal mixed models, all subgroups improved in most outcomes over time. Specifically, over 12months, the nonsymptomatic subgroups had lower LBP intensity and disability levels compared with the WS subgroup, whereas the strong and nonsymptomatic subgroup had better mobility function than the 2 "weak" subgroups. These subgroup classifications may help in tailoring specific interventions in future trials. Special attention should be given to the WS subgroup given their consistently poor LBP and mobility function outcomes. Among older adults with chronic low back pain, there are 3 hip subgroups: "strong and nonsymptomatic," "weak and nonsymptomatic," and "weak and symptomatic." People in these subgroups demonstrate different outcomes and require different treatment; proper identification will result in tailored interventions designed to benefit individual patients. In particular, people in the WS subgroup deserve special attention, because their outcomes are consistently poorer than those in the other subgroups.

Patient‐centered outcomes: Domain importance predicts health care use following physical therapy

Identifying patients with musculoskeletal pain who are at risk for additional health care use is important for improving the value of physical therapists' services. We previously identified three subgroups based on the importance attached by patients to improvements in outcome domains including a (1) Pain and Function Outcomes Important subgroup; (2) Pain Important subgroup; and (3) Multiple Outcome Domains Important subgroup. The primary aim was to determine whether subgroups based on patient-determined outcomes of importance predicted any additional pain-related health care use after an episode of physical therapy. A secondary aim was to determine if subgroup membership predicted use of specific services. Secondary analysis of a longitudinal cohort. Ambulatory outpatient physical therapy clinics. Two hundred forty-six patients seeking physical therapy recruited from the Optimal Screening for Prediction of Referral and Outcome (OSPRO) cohort study. Patients completed a demographic and health history questionnaire, numeric pain rating scale, region-specific disability measure, and Charlson Comorbidity Index. Subgroup membership was determined based on responses to the Patient Centered Outcome Questionnaire. At 1 year, patients reported use of health care since discharge from physical therapy. Separate logistic regression models determined whether subgroup membership predicted additional health care use. Compared to the Pain and Function Outcomes Important subgroup, the Pain Important subgroup had higher adjusted odds (95% confidence interval [CI]) for the primary outcome of any additional health care use (adjusted odds ratio [aOR]2.47, 95% CI 1.01-6.00) and secondary outcomes of opioid use (aOR 9.45, 95% CI 2.87-31.17), injection (aOR 4.09, 95% CI 1.25-13.41), and surgery (aOR 5.10, 95% CI 1.15-22.67). There were no significant differences in health care utilization between the Pain and Function Outcomes Important and Multiple Outcome Domains Important subgroups. In this cohort, patients with a singular focus on pain improvements were at higher risk for additional health care, including opioid use, injection, and surgery. These findings are exploratory and need to be confirmed in other cohorts.

Hierarchical clustering by patient-reported pain distribution alone identifies distinct chronic pain subgroups differing by pain intensity, quality, and clinical outcomes.

BackgroundIn clinical practice, the bodily distribution of chronic pain is often used in conjunction with other signs and symptoms to support a diagnosis or treatment plan. For example, the diagnosis of fibromyalgia involves tallying the areas of pain that a patient reports using a drawn body map. It remains unclear whether patterns of pain distribution independently inform aspects of the pain experience and influence patient outcomes. The objective of the current study was to evaluate the clinical relevance of patterns of pain distribution using an algorithmic approach agnostic to diagnosis or patient-reported facets of the pain experience.Methods and findingsA large cohort of patients (N = 21,658) completed pain body maps and a multi-dimensional pain assessment. Using hierarchical clustering of patients by body map selection alone, nine distinct subgroups emerged with different patterns of body region selection. Clinician review of cluster body maps recapitulated some clinically-relevant patterns of pain distribution, such as low back pain with radiation below the knee and widespread pain, as well as some unique patterns. Demographic and medical characteristics, pain intensity, pain impact, and neuropathic pain quality all varied significantly across cluster subgroups. Multivariate modeling demonstrated that cluster membership independently predicted pain intensity and neuropathic pain quality. In a subset of patients who completed 3-month follow-up questionnaires (N = 7,138), cluster membership independently predicted the likelihood of improvement in pain, physical function, and a positive overall impression of change related to multidisciplinary pain care.ConclusionsThis study reports a novel method of grouping patients by pain distribution using an algorithmic approach. Pain distribution subgroup was significantly associated with differences in pain intensity, impact, and clinically relevant outcomes. In the future, algorithmic clustering by pain distribution may be an important facet in chronic pain biosignatures developed for the personalization of pain management.

A Latent Approach to Understanding Pain in Nursing Home Residents Who are Unable to Self-Report Pain.

ContextPain assessment in people with cognitive impairment is challenging.ObjectiveThe study sought to 1) identify pain subgroups based on staff-assessed pain, agitated and reactive behavior, functional status, and symptoms of depression; and 2) understand if cognitive impairment was associated with transitions between pain subgroups at nursing home admission, 3 months, and 6 months.MethodsUsing national Minimum Data Set 3.0 data (2011–2016), we included 26,816 newly admitted residents with staff-assessed pain at admission, 3 months, and 6 months. Pain subgroups were identified by latent class analysis at each time point. Transitions between pain subgroups were described using latent transition analysis.ResultsFive latent statuses of pain were identified at admission: “Behavioral and Severe Depression” (prevalence stable, severe or worsening cognitive impairment: 11%, mild/moderate or improved cognitive impairment: 10%), “Functional” (21%; 25%), “Physical” (22%; 23%), “Behavioral” (23%, 19%), and “Low” (23%; 24%). Regardless of change in cognitive status, most residents remained in the same pain latent class. Among residents with stable, severe or worsening cognitive impairment, 11% in the “Behavioral” class transitioned to the “Behavioral and Severe Depression” class by 3 months. Fewer residents transitioned between latent classes in the 3- to 6-month period (>80% remained in their 3-month class).ConclusionFor nursing home residents unable to self-report pain, consideration of additional indicators including functioning, depressive symptoms, and agitation may be useful in identifying pain subgroups. Longitudinal changes in the pain subgroups over 6 months post-admission highlight that residents with severe cognitive impairment may be at risk for worsening pain.

Development and Validation of Vikrti Measuring Scale – A Pilot Study

Objective: This is a preliminary report on the development of a scale to measure the pathology of tridoshas in a group of diseases by using the concepts of Āyurveda. Design: The 97-item tridosha diagnosis scale (TDS) was developed based on the translation of Sanskrit verses describing vātaja (V), pittaja (P), and kaphaja (K) vikrti-vriddhi-kshaya and by taking the opinions of experts (fifteen Āyurveda experts, five psychiatrists, and five psychologists). Settings: Arogyadhama holistic health hospital, VYASA, Bangalore, India. Subjects: Thirty-five samples with a history of Diabetes, Back pain, Knee pain, Acidity, and cancer were included in the study. The patients with chronic illness and Cardiac diseases were excluded. Results: The TDS was associated with excellent internal consistency. The Cronbach's alpha for V, P, and K vriddhi and kshaya scales were 0.939,0.945,0.853, 0.867,0.942,0.785 respectively. The Split-Half reliability for V, P, and K vriddhi, kshaya scales were 0.927, 0.962, 0.883, 0.848, 0.960, 0.688, respectively. Scores on vātaja, pittaja, and kaphaja scales were inversely correlated, suggesting that they are mutually exclusive. The three subgroups of back pain, acidity, diabetes had significantly high loadings on the vata vriddhi, pitta vriddhi, kapha vriddhi, respectively. While five cancer patients had significantly high loadings on vataja and kaphaja vriddhi, respectively. Factor analysis revealed that 70 items had good construct validity. Conclusion: The TDS is a reliable and valid instrument. The scores on each of these doshas help in planning intervention.

Pain Phenotypes in Adults Living With Cerebral Palsy.

To identify pain phenotypes among adults living with cerebral palsy (CP) and compare phenotypes of pain intensity, anxiety and depressive symptoms, and self-reported perceived stress. Seventy-one adults with CP presented to the University of Michigan (mean age = 39.3 ± 16.2; 43 women, 28 men). The median of 6 on the American College of Rheumatology fibromyalgia survey was used to classify patients for nociplastic pain centralization. The painDETECT Score was used to classify patients for neuropathic pain. These measures were then used to cross-classify each patient into 1 of 4 possible pain categories: neuropathic, nociplastic, mixed neuropathic/noclipastic, or nociceptive pain (-neuropathic/-nociplastic pain). Twenty-eight adults with CP (39.4%) were classified as nociceptive, 24 (33.8%) as nociplastic, 8 (11.3%) as neuropathic, and 11 (15.5%) as mixed neuropathic/nociplastic. Subgroups differed significantly on average scores on the Brief Pain Inventory pain intensity scale, the Perceived Stress Scale, and on the Patient-Reported Outcomes Measurement Information System measures of anxiety and depression; the nociceptive pain subgroup reported lower pain and emotional distress compared with the other groups. Findings suggest that type of pain is variable among adults with CP and may arise through multiple mechanisms.

Chronic nociplastic pain affecting the musculoskeletal system: clinical criteria and grading system.

Chronic nociplastic pain affecting the musculoskeletal system: clinical criteria and grading system.

Characterizing Multisensory Sensitivity in People with Chronic Pain versus Pain-free Adults

Mechanism-based approaches appears to be promising for pain management. Multisensory sensitivity (MSS) to non-painful stimuli may be a marker to infer central sensitivity processing. MSS is abnormally heightened in those with centrally mediated pain conditions compared to healthy controls. However, whether MSS can differentiate pain subtypes involving different levels of central sensitivity remains unknown. All survey data were collected electronically using REDCap software. 419 pain-free adults and 755 chronic pain patients, particularly FM, migraine or LBP were recruited, with additional pain co-morbidities assessed. All pain groups reported higher MSS than pain-free cohorts (Cohen's d = 0.32 – 1.2, p ≤ 0.0007), after covariates adjustment. MSS was the highest in FM, followed by migraine, and LBP reported the lowest MSS (Cohen's d = 0.37 – 0.96, p ≤ 0.0008). When more broadly grouping patients by pain comorbidities, four pain subgroups were considered: FM + ≥ 2 pain comorbidities (N = 329), FM + ≤ 1 pain comorbidity (N = 177), ≥ 2 pain comorbidities but without FM (n = 188), and any isolated pain condition (n = 56). MSS differed across conditions: FM with or without comorbidities > two or more 2 pain comorbidities but without FM > isolated pain conditions (Cohen's d = 0.43 – 0.98, p ≤ 0.006). Compared to low-average MSS subjects, subjects with the highest MSS level were 2 - 6 times more likely to have FM or COPCs (ORs = 1.86 – 5.98), whereas subjects with the lowest MSS were 55% - 88% less likely (ORs = 0.45 – 0.12). High or low MSS may serve as a risk or resilient factor for chronic pain. MSS could reflect the varying degrees of central mechanisms underlying chronic pain conditions, which suggests MSS may be a valuable marker to profile pain phenotypes clinically, which may improve personalized treatment.

Lumbo-pelvic proprioception in sitting is impaired in subgroups of low back pain-But the clinical utility of the differences is unclear. A systematic review and meta-analysis.

Altered spinal postures and altered motor control observed among people with non-specific low back pain have been associated with abnormal processing of sensory inputs. Evidence indicates that patients with non-specific low back pain have impaired lumbo-pelvic proprioceptive acuity compared to asymptomatic individuals. To systematically review seated lumbo-pelvic proprioception among people with non-specific low back pain. Five electronic databases were searched to identify studies comparing lumbo-pelvic proprioception using active repositioning accuracy in sitting posture in individuals with and without non-specific low back pain. Study quality was assessed by using a modified Downs and Black's checklist. Risk of bias was assessed using an adapted tool for cross-sectional design and case-control studies. We performed meta-analysis using a random effects model. Meta-analyses included subgroup analyses according to disability level, directional subgrouping pattern, and availability of vision during testing. We rated the quality of evidence using the GRADE approach. 16 studies met the eligibility criteria. Pooled meta-analyses were possible for absolute error, variable error, and constant error, measured in sagittal and transverse planes. There is very low and low certainty evidence of greater absolute and variable repositioning error in seated tasks among non-specific low back pain patients overall compared to asymptomatic individuals (sagittal plane). Subgroup analyses indicate moderate certainty evidence of greater absolute and variable error in seated tasks among directional subgroups of adults with non-specific low back pain, along with weaker evidence (low-very low certainty) of greater constant error. Lumbo-pelvic proprioception is impaired among people with non-specific low back pain. However, the low certainty of evidence, the small magnitude of error observed and the calculated "noise" of proprioception measures, suggest that any observed differences in lumbo-pelvic proprioception may be of limited clinical utility. CRD42018107671.

‘Adequacy between medical prescription and intake of analgesics for acute low back and neck pain after presentation at the emergency department – do we prescribe too many tablets?’

ABSTRACT Objectives Acute low back and neck pain account for 3% to 6% of emergency room consultations. In Europe, analgesic prescriptions are issued in boxes. This study, therefore, aims to assess whether this type of packaging is adapted to the real needs of patients. Methods This is a prospective observational multicenter study. Out of a total of 101 eligible patients who consulted the emergency department with acute low back or neck pain of muscular origin, 60 patients were included for statistical analysis. Follow-up was conducted by phone 10 to 14 days after admission. Different parameters were evaluated: the recovery, the amount of remaining tablets, and the demographic characteristics of patients. Results Seventy-five percent of the evaluated patients were asymptomatic at follow-up and no longer taking the prescribed treatment. For all types of prescribed analgesics, a significant number of tablets remained in the drug boxes (P < 0.0001). After the resolution of symptoms, 90% of the studied patients reported a drug surplus. No significant difference was found in terms of patient demographic characteristics. The results were similar for both neck and low back pain subgroups. Conclusion This study suggests that in case of acute low back and neck pain, a significant number of patients who return home after an emergency department consultation have a surplus of analgesics after recovery. These drugs could induce misuse. Moreover, this surplus gives rise to economic and environmental questions. One solution could be to prescribe a number of tablets depending on patients’ pathology instead of entire boxes.

Responsiveness of quantitative sensory testing-derived sensory phenotype to disease-modifying intervention in patients with entrapment neuropathy: a longitudinal study.

The German Research Network on Neuropathic Pain (DFNS) quantitative sensory testing (QST) method for sensory phenotyping is used to stratify patients by mechanism-associated sensory phenotype, theorised to be predictive of intervention efficacy. We hypothesised that change in pain and sensory dysfunction would relate to change in sensory phenotype. We investigated the responsiveness of sensory phenotype to surgery in patients with an entrapment neuropathy. With ethical approval and consent, this observational study recruited patients with neurophysiologically confirmed carpal tunnel syndrome. Symptom and pain severity parameters and DFNS QST were evaluated before and after carpal tunnel surgery. Surgical outcome was evaluated by patient-rated change. Symptom severity score of the Boston Carpal Tunnel Questionnaire and associated pain and paraesthesia subgroups were comparators for clinically relevant change. Quantitative sensory testing results (n = 76) were compared with healthy controls (n = 54). At 6 months postsurgery, 92% participants reported a good surgical outcome and large decrease in pain and symptom severity (P < 0.001). Change in QST parameters occurred for thermal detection, thermal pain, and mechanical detection thresholds with a moderate to large effect size. Change in mechanical pain measures was not statistically significant. Change occurred in sensory phenotype postsurgery (P < 0.001); sensory phenotype was associated with symptom subgroup (P = 0.03) and patient-rated surgical outcome (P = 0.02). Quantitative sensory testing-derived sensory phenotype is sensitive to clinically important change. In an entrapment neuropathy model, sensory phenotype was associated with patient-reported symptoms and demonstrated statistically significant, clinically relevant change after disease-modifying intervention. Sensory phenotype was independent of disease severity and may reflect underlying neuropathophysiology.

Identification and Characteristics of the Three Subgroups of Pain in Chinese Children and Adolescents with Cancer

PurposePain is a distressing symptom for children and adolescents with cancer and is experienced by individuals differently. This study sought to determine subgroups according to their pain experiences, and how demographic, clinical, and quality of life (QOL)-related characteristics might differ across subgroups. Design and methodsThis cross-sectional study recruited 187 pediatric patients with cancer aged 8 to 17 years old and asked them to complete measures of pain intensity, pain duration, pain interference and pain control using the Chinese translation of the validated questionnaire from the Pain Squad app, as well as 7 PROMIS measures assessing QOL-related outcomes. Latent profile analysis (LPA) was used to identify latent subgroups. ResultsThree subgroups of children were identified: low-pain/low-duration (69.5%), moderate-pain/high-duration (19.8%), and high-pain/moderate-duration (10.7%). Hospitalized children were more likely to be in the moderate-pain/high-duration subgroup. Children in the high-pain/moderate-duration subgroup were more likely to be cared for by unemployed caregivers. Scores on depressive symptoms (p = 0.002), anger (p < 0.001), anxiety (p = 0.045), fatigue (p = 0.044), and mobility (p = 0.008) questionnaire were significantly worse in the high-pain/moderate-duration subgroup than the other two subgroup. Practice implicationsThis study provides a scientific foundation for further studies exploring predictive factors related to pain experiences. More targeted treatment strategies targeting the specific characteristics of each subgroup will help improve patients' QOL and use of medical resources. ConclusionsThe 3 identified pain subgroups demonstrate the heterogeneity in pain experiences among pediatric patients with cancer. Knowledge of these subgroups can assist clinicians in better identifying and targeting pain treatment for children with cancer.

Epidemiology of Trauma History and Body Pain: A Retrospective Study of Community-Based Australian Women

To assess whether body pain was associated with different trauma histories (physical injury vs. interpersonal injury [IPI]) within Australian women, along with body pain and trauma history associations with biological and psychological (biopsycho) confounders. A retrospective cross-sectional analysis was conducted on the Australian Longitudinal Study on Women's Health (ALSWH) 1973-1978 birth cohort wave 6 data. Relevant life events were categorized into two types of traumatic experience and included as exposure variables in a multinomial regression model for body pain subgroups. Also, subgroup analyses considered trauma and pain effects and interactions on biopsycho burden. The unadjusted multinomial regression model revealed that a history of physical injury was found to be significantly associated with body pain severity, as was a history of IPI trauma. After the model was adjusted to include biopsycho confounders, the association between IPI and body pain was no longer significant, and post hoc analysis revealed the relationship was instead mediated by biopsycho confounders. Women with a history of IPI and body pain were also found to have the greatest biopsycho (physical functioning, stress, anxiety, and depression) burden. The relationship between IPI and body pain was found to be mediated by biopsycho burden, whereas the relationship between physical injury and body pain was not. Also, a history of IPI was associated with a greater biopsycho burden than was a history of physical injury. These results suggest there is clinical value in considering the comprehensive trauma history of patients with pain when developing their biopsychosocial model of care.

Do chronic low back pain subgroups derived from dynamic quantitative sensory testing exhibit differing multidimensional profiles?

The relationship of pain sensitivity with pain and disability in low back pain (LBP) is complicated. It has been suggested increased understanding of dynamic quantitative sensory testing (QST) might be useful in increasing understanding of these relationships. This study aimed to create subgroups based on participant responses to dynamic QST, profile these subgroups based on multidimensional variables (including clinical measures of pain and disability, psychological and lifestyle variables and static QST), and investigate the association of subgroup membership with levels of pain intensity, LBP-related disability and disability risk at 12-month follow up. Participants (n=273) with dominant axial chronic non-specific LBP with duration of pain >3months were included in this study. At baseline, eligible participants completed a self-report questionnaire to collect demographic, clinical, psychological and lifestyle data prior to dynamic and static QST. Dynamic QST measures were conditioned pain modulation (CPM) and temporal summation (TS). At 12-months follow up, clinical data were collected, including pain intensity and LBP-related disability. Sub-groups were formed by cross-tabulation. Analysis was undertaken to profile dynamic QST subgroup on demographic, clinical, psychological, lifestyle and static QST measures. Associations between dynamic QST subgroups and follow-up clinical variables were examined. Based on dynamic QST, participants were allocated into four subgroups; normal CPM and normal TS (n=34, 12.5%); normal CPM and facilitated TS (n=6, 2.2%); impaired CPM and normal TS (n=186, 68.1%); impaired CPM and facilitated TS (n=47, 17.2%). At baseline no differences were demonstrated between subgroups across most clinical variables, or any psychological or lifestyle measures. The two subgroups with impaired CPM were more likely to have a higher number of painful body areas. Cold pain sensitivity was heightened in both the subgroups with facilitated TS. Subgroups did not differ across pain intensity, LBP-related disability and disability risk stratification at follow-up. The profiles of people with axial LBP did not vary significantly across dynamic QST subgroups, save forthose in groups with impaired CPM being more likely tohave more widespread symptoms and those with facilitated TS having heightened cold pain sensitivity. Further, subgroup membership was not related to future pain and disability. The role of dynamic QST profiles in LBP remains unclear. Further work is required to understand the role of pain sensitivity in LBP. The utility of dynamic QST subgrouping might not be in determining of future disability. Future research might focus on treatment modifying effects of dynamic QST subgroups.

Consistent differences in lumbar spine alignment between low back pain subgroups and genders during clinical and functional activity sitting tests

BackgroundSubgroups of people with low back pain display differences in their lumbar alignment during tests from a clinical examination. However, it is unknown if subgroups display the same patterns during a functional activity test and if gender influences subgroup-related differences. ObjectivesTest if differences in lumbar alignment between two LBP subgroups are 1) present during a functional activity test of preferred sitting and 2) independent of gender. DesignCross-sectional. Method154 participants with chronic low back pain were classified based on the Movement System Impairment Classification System by a physical therapist. Participants performed a functional activity test of preferred sitting and clinical tests of maximum flexed and extended sitting. 3D marker co-ordinate data were collected. Sagittal plane lumbar alignment, indexed by lumbar curvature angle, was calculated. A three-way mixed effect analysis of variance was used to examine effects of test, subgroup, gender, subgroup × test, gender × test and subgroup × gender. Results/findingsThe lumbar rotation with extension subgroup [LCA = −8.0° (−9.5,-6.5)] displayed a more extended lumbar alignment than lumbar rotation [LCA = −5.9° (−7.4,-4.4)]. Women [LCA = −10.7° (−12.3,-9.2)] displayed a more extended lumbar alignment than men [LCA = −3.2° (−4.7,-1.7)]. There was a significant gender × test interaction (p = 0.01). The subgroup × test (p = 0.99) and subgroup × gender (p = 0.76) interactions were not significant. ConclusionsLBP subgroup differences in lumbar alignment are present during preferred sitting. Gender-related differences in lumbar alignment are not driving subgroup differences. These findings highlight the need to use patient-specific clinical characteristics to guide treatment of a functional activity of preferred sitting limited due to low back pain.