Comparison of Low Back Pain Recovery and Persistence: A Descriptive Study of Characteristics at Pain Onset

The clinical course of acute, subacute and persistent low back pain: a systematic review and meta-analysis

BACKGROUND

Understanding the clinical course of low back pain is essential to informing treatment recommendations and patient stratification. Our aim was to update our previous systematic review and meta-analysis to gain a better understanding of the clinical course of acute, subacute and persistent low back pain.

METHODS

To update our 2012 systematic review and meta-analysis, we searched the Embase, MEDLINE and CINAHL databases from 2011 until January 2023, using our previous search strategy. We included prospective inception cohort studies if they reported on participants with acute (< 6 wk), subacute (6 to less than 12 wk) or persistent (12 to less than 52 wk) nonspecific low back pain at study entry. Primary outcome measures included pain and disability (0-100 scale). We assessed risk of bias of included studies using a modified tool and assessed the level of confidence in pooled estimates using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool. We used a mixed model design to calculate pooled estimates (mean, 95% confidence interval [CI]) of pain and disability at 0, 6, 12, 26 and 52 weeks. We treated time in 2 ways: time since study entry (inception time uncorrected) and time since pain onset (inception time corrected). We transformed the latter by adding the mean inception time to the time of study entry.

RESULTS

We included 95 studies, with 60 separate cohorts in the systematic review (n = 17 974) and 47 cohorts (n = 9224) in the meta-analysis. Risk of bias of included studies was variable, with poor study attrition and follow-up, and most studies did not select participants as consecutive cases. For the acute pain cohort, the estimated mean pain score with inception time uncorrected was 56 (95% CI 49-62) at baseline, 26 (95% CI 21-31) at 6 weeks, 22 (95% CI 18-26) at 26 weeks and 21 (95% CI 17-25) at 52 weeks (moderate-certainty evidence). For the subacute pain cohort, the mean pain score was 63 (95% CI 55-71) at baseline, 29 (95% CI 22-37) at 6 weeks, 29 (95% CI 22-36) at 26 weeks and 31 (95% 23-39) at 52 weeks (moderate-certainty evidence). For the persistent pain cohort, the mean pain score was 56 (95% CI 37-74) at baseline, 48 (95% CI 32-64) at 6 weeks, 43 (95% CI 29-57) at 26 weeks and 40 (95% CI 27-54) at 52 weeks (very low-certainty evidence). The clinical course of disability was slightly more favourable than the clinical course of pain.

INTERPRETATION

Participants with acute and subacute low back pain had substantial improvements in levels of pain and disability within the first 6 weeks ( moderate-certainty evidence); however, participants with persistent low back pain had high levels of pain and disability with minimal improvements over time (very low-certainty evidence). Identifying and escalating care in individuals with subacute low back pain who are recovering slowly could be a focus of intervention to reduce the likelihood of transition into persistent low back pain.

PROTOCOL REGISTRATION

PROSPERO - CRD42020207442.

Effects of sling exercises on pain, function, and corticomuscular functional connectivity in individuals with chronic low back pain- preliminary study

BACKGROUND

Individuals with chronic low back pain (CLBP) exhibit altered brain function and trunk muscle activation.

AIM

This study examined the effects of sling exercises on pain, function, and corticomuscular coherence (CMC) in healthy adults and individuals with CLBP.

METHODS

Eight individuals with CLBP and 15 healthy adults received sling exercise training for 6 weeks. Before and after training, participants performed two motor tasks: rapid arm lifts and repeated trunk flexion-extension tasks, and electromyography of the trunk muscles and electroencephalography of the sensorimotor cortex were recorded. Chi-squared test and Mann-Whitney U tests were used for between group comparison, and Wilcoxon signed-rank tests were used for pre- and post-training comparison. Spearman's Rank Correlation Coefficient (Rs) was used to identify for the relationship between motor performance and Corticomuscular coherence.

RESULTS

Sling exercises significantly improved pain (median from 3 to 1, p = .01) and Oswestry Disability Index scores (median from 2.5 to 2, p = .03) in the CLBP group. During rapid arm lifts, individuals with CLBP showed lower beta CMC of the transverse abdominis and internal oblique (Tra/IO) (0.8 vs. 0.49, p = .01) and lumbar erector spinae (0.70 vs. 0.38, p = .04) than the control group at baseline. During trunk flexion-extension, the CLBP group showed higher gamma CMC of the left Tra/IO than the control group at baseline (0.28 vs. 0.16 , p = .001). After training, all CMC became statistically non-significant between groups. The training induced improvement in anticipatory activation of the Tra/IO was positively correlated with the beta CMC (rs = 0.7851, p = .02).

CONCLUSION

A 6-week sling exercises diminished pain and disability in patients with CLBP and improved the anticipatory activation and CMC in some trunk muscles. These improvements were associated with training induced changes in corticomuscular connectivity in individuals with CLBP.

The importance of inflammatory biomarkers in non-specific acute and chronic low back pain: a systematic review

OBJECTIVE

The purpose of this study was to systematically review the evidence on inflammatory biomarkers as analytic predictors of non-specific low back pain (NsLBP). Low back pain (LBP) is the number one cause of disability globally, posing a major health problem that causes an enormous social and economic burden, and there is an increasing interest on the importance of biomarkers in quantifying and even emerge as potential therapeutic tools to LBP.

METHODS

A systematic search was conducted on July 2022 in Cochrane Library, MEDLINE and Web of Science for all the available literature. Cross-sectional, longitudinal cohort or case-control studies that evaluated the relationship between inflammatory biomarkers collected from blood samples and low back pain in humans were considered eligible for inclusion, as well as prospective and retrospective studies.

RESULTS

The systematic database search resulted in a total of 4016 records, of which 15 articles were included for synthesis. Sample size comprised a total of 14,555 patients with LBP (acute LBP (n = 2073); chronic LBP (n = 12482)) and 494 controls. Most studies found a positive correlation between classic pro-inflammatory biomarkers and NsLBP, namely C-reactive protein (CRP), interleukin 1 (IL-1) and IL-1β, interleukin 6 (IL-6) and tumour necrosis factor α (TNF-α). On the other hand, anti-inflammatory biomarker interleukin 10 (IL-10) demonstrated a negative association with NsLBP. Four studies have made direct comparisons between ALBP and CLBP groups regarding their inflammatory biomarkers profile.

CONCLUSIONS

This systematic review found evidence of increased levels of pro-inflammatory biomarkers CRP, IL-6 and TNF-α and decreased levels of anti-inflammatory biomarker IL-10 in patients with LBP. Hs-CRP was not correlated with LBP. There is insufficient evidence to associate these findings with the degree of pain severity or the activity status of the lumbar pain over time.

Differences in dynamic balance control based on pain catastrophizing level in individuals with nonspecific chronic low back pain

BACKGROUND

Pain catastrophization (PC) is related to motor control changes in individuals with nonspecific chronic low back pain (NSCLBP). However, differences in dynamic balance control based on the level of PC still remain unclear in these individuals.

OBJECTIVE

The aim of this study was to compare the dynamic balance control between healthy controls and individuals with NSCLBP with high and low PC.

METHODS

Forty individuals with NSCLBP and 20 healthy participants were enrolled in this cross-sectional study. Individuals with NSCLBP were classified into two groups of high and low PC. Dynamic balance control was assessed using the Modified Star Excursion Balance Test (MSEBT), Five-Time Sit-to-Stand Test (FTSST), and Timed Up and Go Test (TUGT).

RESULTS

Statistical analyses showed that mean values of reach distances in the anterior, posteromedial, and posterolateral directions of the MSEBT were significantly lower in individuals with NSCLBP with high PC compared to low PC (p = .04, p = .01, and p = .04, respectively) and healthy controls (p < .001, p = .001, and p = .006, respectively). In addition, for both the FTSS and TUG tests, the mean time was significantly greater in individuals with NSCLBP with high PC compared to low PC (p < .001 and p = .004, respectively) and healthy controls (p < .001).

CONCLUSIONS

Our results showed poor dynamic balance control in individuals with NSCLBP with high PC. This suggests that PC could contribute to the impaired dynamic balance control in individuals with NSCLBP. Combining balance exercises and cognitive-behavioral treatments targeting PC may be useful for the improvement of dynamic balance control in individuals with NSCLBP with high PC.

Pain sensation and gut microbiota profiles in older adults with heart failure

Objectives

Patients with heart failure (HF) experience severe pain and may have altered pain sensation; however, the underlying mechanisms of these symptoms are not yet fully understood. Identifying pain sensation and genomic biomarkers of pain in older adults with HF is a critical step toward developing personalized interventions to improve pain management and outcomes. This study aimed to investigate the differences in pain sensation, gut microbiota, self-reported pain, and symptoms in older adults with and without HF.

Methods

Twenty older adults with HF and age-matched healthy controls (HCs) were recruited in the Northeastern United States. Quantitative sensory testing and conditioned pain modulation were performed on the nondominant upper arm to detect the mechanical, thermal, and pressure pain thresholds and pain modulations. Stool samples were collected, and the 16S rRNA V4 gene region of stool samples was sequenced and processed using the Mothur 1.42.3 pipeline. Self-reported pain and symptoms were measured by the Brief Pain Inventory and the NIH Patient-reported Outcomes Measurement Information System. The associations between pain sensation, gut microbiota α-diversity indices, and pain and symptoms were explored using the Spearman correlations.

Results

The HF and HC subjects' mean ages were 73.50 (SD = 8.33) and 67.10 (SD = 7.64), respectively. The HF subjects reported significantly higher pain intensity and interference, sleep disturbance, fatigue, anxiety, and depression than the HCs. The HF subjects also had a significantly lower level of physical function and participation in social roles and activities. Compared with the HCs, the HF subjects had significantly altered conditioned pain modulation heat effect and gut microbiota compositions and predicted metabolic functions. The Statistical Analysis Of Metagenomic Profiles indicated that the HF subjects had a significantly decreased cardiac muscle contraction pathway compared with the HCs. The correlation analysis showed that the quantitative sensory testing profiles and gut microbiota diversity index were significantly associated with pain and symptoms in older adults with HF.

Conclusions

Older adults with HF had more severe self-reported pain and symptoms, altered pain sensation, and different gut microbiota composition and function compared with age-matched HCs. Pain sensation and gut microbiota may contribute to pain and symptoms in older adults with HF and could serve as biomarkers of pain and symptoms of HF. Further research with a larger sample size is warranted to confirm these findings.

A feasibility study on yoga's mechanism of action for chronic low back pain: psychological and neurophysiological changes, including global gene expression and DNA methylation, following a yoga intervention for chronic low back pain

INTRODUCTION

Yoga has been shown to reduce pain and improve function in populations with chronic low back pain (cLBP), yet the underlying molecular mechanisms remain elusive. This study examined the feasibility and acceptability of a yoga research protocol, including recruitment, retention, and data collection, and investigated the preliminary effects of yoga on psychological and neurophysiological functions, including gene expression and DNA methylation profiles, in participants with cLBP.

METHODS

A one-arm trial was conducted with 11 participants with cLBP who enrolled in a 12-week yoga intervention. Data on subjective pain characteristics, quantitative sensory testing, and blood for analysis of differentially expressed genes and CpG methylation was collected prior to the start of the intervention and at study completion.

RESULTS

Based on pre-determined feasibility and acceptability criteria, the yoga intervention was found to be feasible and highly acceptable to participants. There was a reduction in pain severity, interference, and mechanical pain sensitivity post-yoga and an increase in emotion regulation and self-efficacy. No adverse reactions were reported. Differential expression analysis demonstrated that the yoga intervention induced increased expression of antisense genes, some of which serve as antisense to known pain genes. In addition, there were 33 differentially hypomethylated positions after yoga (log2 fold change ≥ 1), with enrichment of genes involved in NIK/NF-kB signaling, a major pathway that modulates immune function and inflammation.

DISCUSSION/CONCLUSIONS

The study supports the feasibility and acceptability of the proposed protocol to test a specific mechanism of action for yoga in individuals with cLBP. These results also support the notion that yoga may operate through our identified psychological and neurophysiologic pathways to influence reduced pain severity and interference.

Sex-Related Pain Behavioral Differences following Unilateral NGF Injections in a Rat Model of Low Back Pain

Low back pain (LBP) is a globally prevalent and costly societal problem with multifactorial etiologies and incompletely understood pathophysiological mechanisms. To address such shortcomings regarding the role of neurotrophins in the underlying mechanisms of pain, an LBP model was developed in rats involving two unilateral intramuscular injections of nerve growth factor (NGF) into deep trunk muscles. To date, behavioral investigations of this NGF-LBP model have been limited, especially as it pertains to female pain behaviors. This study compared mechanical sensitivity to noxious (hyperalgesia) and non-noxious (hypersensitivity) stimuli in control and NGF-injected male and female rats through pain resolution. Although the baseline testing revealed no differences between males and females, NGF-injected females demonstrated prolonged ipsilateral deep trunk mechanical hyperalgesia that resolved seven days later than males. Moreover, females showed bilateral trunk mechanical sensitivity to noxious and non-noxious stimuli compared to only ipsilateral behaviors in males. Sex differences were also observed in the severity of behavioral responses, with females displaying greater mean differences from baseline at several timepoints. Overall, these NGF-LBP behavioral findings mirror some of the sex differences reported in the clinical presentation of LBP and accentuate the translatability of this NGF-LBP model. Future studies using this LBP-NGF model could help to elucidate the neurobiological mechanisms responsible for the development, severity, and/or resolution of muscular LBP as well as to provide insights into the processes governing the transition from acute to chronic LBP.

Neurophysiological and transcriptomic predictors of chronic low back pain: Study protocol for a longitudinal inception cohort study

Chronic low back pain is one of the most common, costly, and debilitating pain conditions worldwide. Increased mechanistic understanding of the transition from acute to chronic low back and identification of predictive biomarkers could enhance the clinical assessment performed by healthcare providers and enable the development of targeted treatment to prevent and/or better manage chronic low back pain. This study protocol was designed to identify the neurological and transcriptomic biomarkers predictive of chronic low back pain at low back pain onset. This is a prospective descriptive longitudinal inception cohort study that will follow 340 individuals with acute low back pain and 40 healthy controls over 2 years. To analyze the neurophysiological and transcriptomic biomarkers of low back pain, the protocol includes psychological and pain-related survey data that will be collected beginning within 6 weeks of low back pain onset (baseline, 6, 12, 24, 52 weeks, and 2 years) and remotely at five additional time points (8, 10, 16, 20 weeks, and 18 months). Quantitative sensory testing and collection of blood samples for RNA sequencing will occur during the six in-person visits. The study results will describe variations in the neurophysiological and transcriptomic profiles of healthy pain-free controls and individuals with low back pain who either recover to pain-free status or develop chronic low back pain.

Quantitative Sensory Testing Across Chronic Pain Conditions and Use in Special Populations

Chronic pain imposes a significant burden to the healthcare system and adversely affects patients' quality of life. Traditional subjective assessments, however, do not adequately capture the complex phenomenon of pain, which is influenced by a multitude of factors including environmental, developmental, genetic, and psychological. Quantitative sensory testing (QST), established as a protocol to examine thermal and mechanical sensory function, offers insight on potential mechanisms contributing to an individual's experience of pain, by assessing their perceived response to standardized delivery of stimuli. Although the use of QST as a research methodology has been described in the literature in reference to specific pain populations, this manuscript details application of QST across a variety of chronic pain conditions. Specific conditions include lower extremity chronic pain, knee osteoarthritis, chronic low back pain, temporomandibular joint disorder, and irritable bowel syndrome. Furthermore, we describe the use of QST in placebo/nocebo research, and discuss the use of QST in vulnerable populations such as those with dementia. We illustrate how the evaluation of peripheral sensory nerve function holds clinical promise in targeting interventions, and how using QST can enhance patient education regarding prognostic outcomes with particular treatments. Incorporation of QST methodology in research investigations may facilitate the identification of common mechanisms underlying chronic pain conditions, guide the development of non-pharmacological behavioral interventions to reduce pain and pain-related morbidity, and enhance our efforts toward reducing the burden of chronic pain.

Contribution of COMT and BDNF Genotype and Expression to the Risk of Transition From Acute to Chronic Low Back Pain

OBJECTIVES

A number of factors, including heritability and the environment, contribute to risk of transition from acute low back pain to chronic low back pain (CLBP). The aim of this study was to (1) compare somatosensory function and pain ratings at low back pain (LBP) onset between the acute low back pain and CLBP conditions and (2) evaluate associations between BDNF and COMT polymorphisms and expression levels at LBP onset to acute and chronic pain burden and risk for transition to the chronic pain state.

METHODS

In this longitudinal study, 220 participants were enrolled following recent onset of LBP and data were collected until the LBP resolved or until the end of the study at 6 months. Forty-two participants' pain resolved before 6 weeks from onset and 42 participants continued to have pain at 6 months. Patient-reported pain burden, somatosensory function (quantitative sensory testing), and blood samples were collected at each study visit.

RESULTS

CLBP is associated with greater pain burden and somatosensory hypersensitivity at the time of LBP onset. COMT rs4680 genotype (GG) was associated with acute cold pain sensitivity and with the risk for transition to CLBP while COMT expression was independently associated with risk for transition.

DISCUSSION

CLBP was characterized by higher reported pain burden and augmented hypersensitivity at LBP onset. COMT expression and genotype were associated with acute pain burden and likelihood of transition to CLBP.

Investigating key predictors of persistent low back pain: A focus on psychological stress

AIM

To investigate the degree to which psychological stress, self-reported pain scores, and pain sensitivity during an acute state of low back pain (LBP) predict the development of persistent LBP trajectories.

BACKGROUND

Identifying which factors influence LBP trajectories is critical to understand why some individuals experience persistent LBP and to illuminate areas for nursing intervention.

METHODS

A secondary data analysis of a prospective study examining trajectories of LBP was conducted. The sample was comprised of 217 adults with acute-onset LBP recruited from the community and followed over 24 weeks. Variables of interest included demographic data, perceived stress scores, self-reported pain scores, and somatosensory characteristics collected within the first 4 weeks of LBP onset. The data were analyzed using non-parametric bivariate comparisons and a semi-parametric Cox proportional hazards model with interval-censoring.

RESULTS

Individuals with higher psychological stress scores were less likely to experience pain resolution (Hazard ratio [HR] = 0.555, 95% confidence interval [CI] = 0.36-0.85, p = 0.02). After adjustment for covariates in the final model, the analysis revealed household income (HR = 2.79, 95% CI [1.63-4.67], p < 0.001) to be the dominant predictor of LBP persistence in this sample.

CONCLUSION

Heightened psychological stress and pain severity as well as decreased pressure pain thresholds were indicated as influential factors of LBP trajectories. Household income was identified as the dominant predictor, demonstrating that individuals with a higher household income were more likely to resolve their pain. Strategies which integrate assessment of stress, self-reported pain scores, pain sensitivity, and social determinants for patients experiencing pain are needed to advance nursing care.

Alterations in pronociceptive and antinociceptive mechanisms in patients with low back pain: a systematic review with meta-analysis

Altered pronociceptive and antinociceptive mechanisms are often implicated in painful conditions and have been increasingly studied over the past decade. For some painful conditions, alterations are well-established, but in populations with low back pain (LBP), there remains considerable debate whether these mechanisms are altered. The present systematic review aimed to address this issue by identifying studies assessing conditioned pain modulation (CPM) and/or temporal summation of pain (TSP) in patients with LBP, comparing with either a healthy control group or using a method with reference data available. Qualitative synthesis and quantitative meta-analysis of group differences were performed. For CPM and TSP, 20 and 29 original articles were eligible, with data for meta-analysis obtainable from 18 (1500 patients and 505 controls) and 27 (1507 patients and 1127 controls) studies, respectively. Most studies were of poor-to-fair quality with significant heterogeneity in study size, population, assessment methodology, and outcome. Nonetheless, CPM was impaired in patients with LBP compared with controls (standardized mean difference = -0.44 [-0.64 to -0.23], P < 0.001), and the magnitude of this impairment was related to pain chronicity (acute/recurrent vs chronic, P = 0.003), duration (RS = -0.62, P = 0.006), and severity (RS = -0.54, P = 0.02). Temporal summation of pain was facilitated in patients with LBP compared with controls (standardized mean difference = 0.50 [0.29-0.72], P < 0.001), and the magnitude of this facilitation was weakly related to pain severity (RS= 0.41, P = 0.04) and appeared to be influenced by test modality (P < 0.001). Impaired CPM and facilitated TSP were present in patients with LBP compared with controls, although the magnitude of differences was small which may direct future research on the clinical utility.

Central Sensitivity Is Associated with Poor Recovery of Pain: Prediction, Cluster, and Decision Tree Analyses

The process of pain recovery varies and can include the recovery, maintenance, or worsening of symptoms. Many cases of patients with pain show a tendency of recovering as predicted; however, some do not. The characteristics of cases that do not fit the prediction of pain recovery remain unclear. We performed cluster and decision tree analyses to reveal the characteristics in cases that do not fit the prediction of pain recovery. A total of 43 patients with musculoskeletal pain (nonoperative: 22 patients, operative: 13 patients) and central pain (brain disease: 5 patients, spinal cord disease: 3 patients) were included in this longitudinal study. Central sensitivity syndrome (CSS) outcome measures (Central Sensitisation Inventory), pain intensity-related outcome measures (Short-Form McGill Pain Questionnaire-2 (SFMPQ-2)), and cognitive-emotional outcome measures (Hospital Anxiety and Depression Scale and Pain Catastrophising Scale-4) of all patients were assessed at baseline and after 1-2 months. Regression analysis was used to calculate pain recovery prediction values. A hierarchical cluster analysis based on the predicted change of SFMPQ-2 and the observed change of SFMPQ-2 was used to extract subgroups that fit and those that do not fit pain recovery prediction. To extract the characteristics of subgroups that do not fit the prediction of pain recovery, a decision tree analysis was performed. The level of significance was set at 5%. In the results of cluster analysis, patients were classified into three subgroups. Cluster 1 was characterised by worse pain intensity from baseline, cluster 2 by pain, having recovered less and mildly than the predicted value, and Cluster 3 by a marked recovery of pain. In the results of the decision tree analysis, the CSI change was extracted as an indicator related to the classification of all clusters. Our findings suggest that the poor improvement of CSS is characteristic in cases that do not fit the prediction of pain recovery.

Psychological and physical factors related to disability in chronic low back pain

BACKGROUND

Chronic low back pain (CLBP) is a public health problem that causes high levels of disability. Psychological and physical factors could play a critical role in the disability perception of patients.

OBJECTIVE

The objective was to identify the psychological and physical factors associated with CLBP disability in patients and assess differences between asymptomatic subjects and CLBP patients through physical tests and psychological self-reports.

METHODS

A cross-sectional study was performed. Total sample of 80 participants were classified into two groups: patients with CLBP (n= 49) and asymptomatic subjects (i.e. the control group) (n= 31). The physical tests included lower back range of motion (LBROM), postural stability, lower back strength (LBS), and lumbopelvic motor control tests. The psychological self-reports included low back disability (Roland Morris Disability Questionnaire), self-efficacy, pain catastrophizing, and pain-related fear.

RESULTS

Self-efficacy and LBS displayed moderate negative correlations with disability in patients with CLBP (R=-0.47 and -0.40, respectively). Disability was predicted by self-efficacy and LBROM (β=-0.45 and -033 respectively, p< 0.01), explaining 30% of the variance in these patients. The comparative analysis showed statistically significant differences between groups in the physical/psychological variables (p< 0.01); however, the effect-sizes were small for all these variables.

CONCLUSIONS

The results of this study highlight the relevance of psychological and physical factors in CLBP patient disability. Evaluation and treatment in CLBP patients should take these factors into account.

Effects of Physical Activity on Neurophysiological and Gene Expression Profiles in Chronic Back Pain: Study Protocol

BACKGROUND

Despite the emphasis on exercise to reduce pain and improve function among people with chronic low back pain (cLBP), little is known about the underlying mechanism of the impact of exercise on the neurophysiological and gene transcription alterations that characterize cLBP.

OBJECTIVES

To present a study protocol to examine the feasibility, acceptability, and initial efficacy of Problem-Solving Pain to Enhance Living Well (PROPEL) with the support of nurse consultations and wearable activity-tracking technology on self-management (SM) knowledge, skills, physical activity, and pain and to examine the differential neurophysiological and gene expression profiles in cLBP participants from pre- to post-PROPEL.

METHODS

A pretest and posttest study is employed on 40 adults ages 18-60 years with cLBP who do not have serious complications and/or comorbidities that affect sensorimotor function. Participants will receive video modules focused on SM and biweekly phone consultations to facilitate symptom monitoring and problem-solving while increasing physical activity frequency and duration. Participants will be assessed for outcomes including SM skills, physical activity, and pain every 2 weeks for 12 weeks. We will examine the participants' differential neurophysiological and gene expression profiles at 12 weeks postintervention and correlate these outcomes with the total duration of physical activity.

RESULTS

The study began in September 2018. Of the 99 subjects that were screened, 23 were enrolled and 8 completed data collection.

DISCUSSION

Comparing the neurophysiological and gene expression profiles of people with cLBP exposed to PROPEL could inform the development of interventions that offer personalized physical activity dosage along with general SM support. Web-based programs such as PROPEL have the potential to enhance accessibility of evidence-based interventions that improve functionality and quality of life among people living with cLBP.

Elevated Production of Nociceptive CC Chemokines and sE-Selectin in Patients With Low Back Pain and the Effects of Spinal Manipulation: A Nonrandomized Clinical Trial

BACKGROUND

The involvement of inflammatory components in the pathophysiology of low back pain (LBP) is poorly understood. It has been suggested that spinal manipulative therapy (SMT) may exert anti-inflammatory effects.

PURPOSE

The purpose of this study was to determine the involvement of inflammation-associated chemokines (CC series) in the pathogenesis of nonspecific LBP and to evaluate the effect of SMT on that process.

METHODS

Patients presenting with nonradicular, nonspecific LBP (minimum pain score 3 on 10-point visual analog scale) were recruited according to stringent inclusion criteria. They were evaluated for appropriateness to treat using a high velocity low amplitude manipulative thrust in the lumbar-lumbosacral region. Blood samples were obtained at baseline and following the administration of a series of 6 high velocity low amplitude manipulative thrusts on alternate days over the period of 2 weeks. The in vitro levels of CC chemokine ligands (CCL2, CCL3, and CCL4) production and plasma levels of an inflammatory biomarker, soluble E-selectin (sE-selectin), were determined at baseline and at the termination of treatments 2 weeks later.

RESULTS

Compared with asymptomatic controls baseline production of all chemokines was significantly elevated in acute (P=0.004 to <0.0001), and that of CCL2 and CCL4 in chronic LBP patients (P<0.0001). Furthermore, CCL4 production was significantly higher (P<0.0001) in the acute versus chronic LBP group. sE-selectin levels were significantly higher (P=0.003) in chronic but not in acute LBP patients. Following SMT, patient-reported outcomes showed significant (P<0.0001) improvements in visual analog scale and Oswestry Disability Index scores. This was accompanied by a significant decline in CCL3 production (P<0.0001) in both groups of patients. Change scores for CCL4 production differed significantly (P<0.0001) only for the acute LBP cohort, and no effect on the production of CCL2 or plasma sE-selectin levels was noted in either group.

CONCLUSIONS

The production of chemotactic cytokines is significantly and protractedly elevated in LBP patients. Changes in chemokine production levels, which might be related to SMT, differ in the acute and chronic LBP patient cohorts.

From acute to persistent low back pain: a longitudinal investigation of somatosensory changes using quantitative sensory testing-an exploratory study

Introduction

Chronic low back pain (LBP) is commonly associated with generalised pain hypersensitivity. It is suggested that such somatosensory alterations are important determinants for the transition to persistent pain from an acute episode of LBP. Although cross-sectional research investigating somatosensory function in the acute stage is developing, no longitudinal studies designed to evaluate temporal changes have been published.

Objectives

This exploratory study aimed to investigate the temporal development of somatosensory changes from the acute stage of LBP to up to 4 months from onset.

Methods

Twenty-five people with acute LBP (<3 weeks' duration) and 48 pain-free controls were prospectively assessed at baseline using quantitative sensory testing with the assessor blinded to group allocation, and again at 2 and 4 months. Psychological variables were concurrently assessed. People with acute LBP were classified based on their average pain severity over the previous week at 4 months as recovered (≤1/10 numeric rating scale) or persistent (≥2/10 numeric rating scale) LBP.

Results

In the persistent LBP group, (1) there was a significant decrease in pressure pain threshold between 2 and 4 months (P < 0.013), and at 4 months, pressure pain threshold was significantly different from the recovered LBP group (P < 0.001); (2) a trend towards increased temporal summation was found at 2 months and 4 months, at which point it exceeded 2 SDs beyond the pain-free control reference value. Pain-related psychological variables were significantly higher in those with persistent LBP compared with the recovered LBP group at all time points (P < 0.05).

Conclusion

Changes in mechanical pain sensitivity occurring in the subacute stage warrant further longitudinal evaluation to better understand the role of somatosensory changes in the development of persistent LBP. Pain-related cognitions at baseline distinguished persistent from the recovered LBP groups, emphasizing the importance of concurrent evaluation of psychological contributors in acute LBP.

Quantitative Sensory Testing and Current Perception Threshold Testing in Patients With Chronic Pain Following Lower Extremity Fracture

BACKGROUND

Chronic pain is a significant problem for patients with lower extremity injuries. While pain hypersensitivity has been identified in many chronic pain conditions, it is not known whether patients with chronic pain following lower extremity fracture report pain hypersensitivity in the injured leg.

PURPOSE

To quantify and compare peripheral somatosensory function and sensory nerve activation thresholds in persons with chronic pain following lower extremity fractures with a cohort of persons with no history of lower extremity fractures.

METHOD

This was a cross-sectional study where quantitative sensory testing and current perception threshold testing were conducted on the injured and noninjured legs of cases and both legs of controls.

RESULTS

A total of 14 cases and 28 controls participated in the study. Mean time since injury at the time of testing for cases was 22.3 (standard deviation = 12.1) months. The warmth detection threshold ( p = .024) and nerve activation thresholds at 2,000 Hz ( p < .001) and 250 Hz ( p = .002), respectively, were significantly higher in cases compared to controls.

CONCLUSION

This study suggests that patients with chronic pain following lower extremity fractures may experience hypoesthesia in the injured leg, which contrasts with the finding of hyperesthesia previously observed in other chronic pain conditions but is in accord with patients with nerve injuries and surgeries. This is the first study to examine peripheral sensory nerve function at the site of injury in patients with chronic pain following lower extremity fractures using quantitative sensory testing and current perception threshold testing.

Circulating Lipids and Acute Pain Sensitization: An Exploratory Analysis

BACKGROUND

In individuals with low back pain, higher lipid levels have been documented and were associated with increased risk for chronic low back pain.

OBJECTIVES

The purpose of this research was to identify plasma lipids that discriminate participants with acute low back pain with or without pain sensitization as measured by quantitative sensory testing.

METHODS

This exploratory study was conducted as part of a larger parent randomized controlled trial. A cluster analysis of 30 participants with acute low back pain revealed two clusters: one with signs of peripheral and central sensitivity to mechanical and thermal stimuli and the other with an absence of peripheral and central sensitivity. Lipid levels were extracted from plasma and measured using mass spectroscopy.

RESULTS

Triacylglycerol 50:2 was significantly higher in participants with peripheral and central sensitization compared to the nonsensitized cluster. The nonsensitized cluster had significantly higher levels of phosphoglyceride 34:2, plasmenyl phosphocholine 38:1, and phosphatidic acid 28:1 compared to participants with peripheral and central sensitization. Linear discriminant function analysis was conducted using the four statistically significant lipids to test their predictive power to classify those in the sensitization and no-sensitization clusters; the four lipids accurately predicted cluster classification 58% of the time (R = .58, -2 log likelihood = 14.59).

DISCUSSION

The results of this exploratory study suggest a unique lipidomic signature in plasma of patients with acute low back pain based on the presence or absence of pain sensitization. Future work to replicate these preliminary findings is underway.

Biological determinants of health: Genes, microbes, and metabolism exemplars of nursing science

BACKGROUND

Increasingly, nurse scientists are incorporating "omics" measures (e.g., genomics, transcriptomics, proteomics, and metabolomics) in studies of biologic determinants of health and behavior. The role of omics in nursing science can be conceptualized in several ways: (a) as a portfolio of biological measures (biomarkers) to monitor individual risk, (b) as a set of combined data elements that can generate new knowledge based on large and complex patient data sets, (c) as baseline information that promotes health education and potentially personalized interventions, and (d) as a platform to understand how environmental parameters (e.g., diet) interact with the individual's physiology.

PURPOSE

In this article, we provide exemplars of nursing scientists who use omics to better understand specific health conditions.

METHODS

We highlight various ongoing nursing research investigations incorporating omics technologies to study chronic pain vulnerability, risk for a pain-related condition, cardiometabolic complications associated with pregnancy, and as biomarkers of response to a dietary intervention.

DISCUSSION

Omics technologies add an important dimension to nursing science across many foci of investigation. However, there are also challenges and opportunities for nurse scientists who consider using omics in their research.

CONCLUSION

The integration of omics holds promise for increasing the impact of nursing research and practice on population health outcomes.