ISSLS PRIZE IN CLINICAL SCIENCE 2018: longitudinal analysis of inflammatory, psychological, and sleep-related factors following an acute low back pain episode-the good, the bad, and the ugly

Subgrouping People With Acute Low Back Pain Based on Psychological, Sensory, and Motor Characteristics: A Cross-Sectional Study

BACKGROUND

Clustering helps identify patient subgroups with similar biopsychosocial profiles in acute low-back pain (LBP). Motor factors are common treatment targets and are associated with disability but have not been included in acute LBP cluster development. This study aimed to identify subgroups of individuals with acute LBP based on motor, sensory and psychological characteristics and to compare these subgroups regarding clinical outcomes.

METHODS

Ninety-nine participants with acute LBP were recruited, and motor (bending range of motion [ROM], flexion relaxation), pain sensitivity (pressure-pain thresholds, temporal summation of pain) and psychological factors (pain catastrophising, kinesiophobia, self-efficacy) were measured, along with pain, disability and demographics.

RESULTS

Principal component analysis accounted for 66.03% of the variance. Four component scores were entered in a hierarchical linear clustering model, deriving 3 subgroups ('mild features' n = 39, 'sensorimotor' n = 35 and 'psychomotor' n = 25). Between-cluster comparisons revealed significant differences in motor, sensory and psychological variables (p < 0.05). Sensorimotor and psychomotor clusters had higher flexion-relaxation ratios (mean difference: > 0.2), greater disability (mean difference: > 7/100) and smaller ROM (mean difference: 7 cm) compared to the 'mild' group. The sensorimotor cluster mostly exhibited higher temporal summation of pain (mean difference: > 1.3/10) and lower pressure-pain thresholds (mean difference: > 1.2 kg/cm2) than 'mild' and psychomotor clusters. The psychomotor cluster showed higher kinesiophobia (mean difference: > 6/44) and pain catastrophising (mean difference: > 12/52) than 'mild' and sensorimotor groups.

CONCLUSION

Findings indicate 3 subgroups, suggesting that motor factors may add granularity to acute LBP clusters. Stratified care based on these subgroups may help refine treatment pathways for acute LBP.

SIGNIFICANCE STATEMENT

Including motor factors in cluster development adds a clinically relevant metric to describe people with acute LBP and generates insight into underlying mechanisms of motor adaptation. Longitudinal testing is required to see if these subgroups are differentially related to short- and long-term pain and disability.

The role and treatment potential of the complement pathway in chronic pain

The role of the complement system in pain syndromes has garnered attention on the back of preclinical and clinical evidence supporting its potential as a target for new analgesic pharmacotherapies. Of the components that make up the complement system, component 5a (C5a) and component 3a (C3a) are most strongly and consistently associated with pain. Receptors for C5a are widely found in immune resident cells (microglia, astrocytes, sensory neuron-associated macrophages (sNAMs)) in the central nervous system (CNS) as well as hematogenous immune cells (mast cells, macrophages, T-lymphocytes, etc.). When active, as is often observed in chronic pain conditions, these cells produce various inflammatory mediators including pro-inflammatory cytokines. These events can trigger nervous tissue inflammation (neuroinflammation) which coexists with and potentially maintains peripheral and central sensitization. C5a has a likely critical role in initiating this process highlighting its potential as a promising non-opioid target for treating pain. This review summarizes the most up-to-date research on the role of the complement system in pain with emphasis on the C5 pathway in peripheral tissue, dorsal root ganglia (DRG) and the CNS, and explores advances in complement-targeted drug development and sex differences. A perspective on the optimal application of different C5a inhibitors for different types (e.g., neuropathic, post-surgical and chemotherapy-induced pain, osteoarthritis pain) and stages (e.g., acute, subacute, chronic) of pain is also provided to help guide future clinical trials. PERSPECTIVE: This review highlights the role and mechanisms of complement components and their receptors in physiological and pathological pain. The potential of complement-targeted therapeutics for the treatment of chronic pain is also explored with a focus on C5a inhibitors to help guide future clinical trials.

Transition from acute to chronic low back pain in a community-based cohort

The transition from acute to chronic low back pain (LBP) in community settings is not well understood. The purpose of this study was to assess the feasibility of recruitment and estimate the transition and continuation of chronic LBP. We also explored characteristics associated with this transition to chronic LBP. We enrolled n = 131 participants, of which n = 118 (90 %) completed 3-month outcomes and n = 111 (85 %) completed 6-month outcomes. Acute LBP was defined by a duration of < 4 weeks and a 30-day LBP-free period before the current acute episode. Chronic LBP was defined as pain most or every day over the past 3 months. The transition from acute to chronic LBP at 3 months was 32.2 % (38/118), and at 6 months, 80.6 % (25/31) of participants who transitioned at 3 months continued to have chronic LBP at 6 months. Participants with more frequent acute LBP and at an intensity of 30/100 were more likely to transition to chronic LBP (Risk Ratio (RR)= 3.13, 95 % Confidence Interval (CI) 1.84, 5.30) and continue to have chronic LBP at 6-months (RR=3.10, 95 % CI 1.48, 6.08). Higher risk on the STarT Back Screening Tool was associated with the transition to chronic LBP at 3 months (RR=1.73, 95 % CI 1.28, 2.35) and continuation of chronic LBP at 6 months (RR=1.26, 95 % CI 1.10, 1.45). The recruitment of acute LBP was feasible in a community setting. Acute LBP is a common condition in the community and frequently transitions to chronic LBP, suggesting the potential for substantial burden in the community. PERSPECTIVE: This article presents the feasibility of conducting a community-based study to describe the transition, continuation, and psychosocial predictors of acute to chronic low back pain. These findings could help identify community participants at high risk of incident and continued chronic low back pain.

Potential use of salivary TNF-α as a vaccine-induced pain biomarker in people with cerebral palsy and communication disorders

BACKGROUND

Pain in people with cerebral palsy (CP) has been classically underestimated and poorly treated, particularly in individuals with impaired communication skills.

OBJECTIVE

To analyze changes in different salivary metabolites and pain behavior scales after a painful procedure in adults with CP and adults with typical development.

METHODS

Salivary levels of sTNF-α, sIgA, Cortisol, FRAP, ADA and Alpha Amylase, as well as 3 observational pain scales (Wong-Baker, Non-Communicating Adults Pain Checklist and Facial Action Coding System) were assessed before and after an intramuscular injection in 30 Individuals with CP and 30 healthy controls. Video recording of face expression was performed during the procedure for offline analysis.

RESULTS

Pain in subjects with CP was higher than in healthy controls after the intramuscular injection as displayed by observational scales. sTNF-α experienced a significant post-stimulus increase in both groups and that increase shows a tendency to correlate with the observational scales scores. Other biomarkers classically associated with stress (cortisol, Alpha Amylase) remain stable.

CONCLUSION

sTNF-α might be a promising pain indicator. Further research using controlled painful stimuli of greater intensity and pain self-reports, would be necessary to better understand its use as a pain biomarker.

Characterizing Acute Low Back Pain in a Community-Based Cohort: Results from a Feasibility Cohort Study

Introduction

Acute low back pain (LBP) is a common experience; however, the associated pain severity, pain frequency, and characteristics of individuals with acute LBP in community settings have yet to be well understood. In this manuscript, two acute-LBP severity categorization definitions were developed: 1) pain impact frequency (impact-based) and 2) pain intensity (intensity-based) severity categories. The purpose of this manuscript is to describe and then compare these acute-LBP severity groups in the following characteristics: 1) sociodemographic, 2) general and physical health, and 3) psychological using a feasibility cohort study.

Methods

This cross-sectional study used baseline data from 131 community-based participants with acute LBP (<4 weeks duration before screening and ≥30 pain-free days before acute LBP onset). Descriptive associations were calculated as prevalence ratios of categorical variables and Hedges' g for continuous variables.

Results

Our analyses identified several large associations for impact-based and intensity-based categories with global mental health, global physical health, STarT Back Screening Tool risk category, and general health. Larger associations were found with social constructs (racially and ethnically minoritized, performance of social roles, and isolation) when using the intensity-based versus impact-based categorization.

Discussion

This study adds to the literature by providing standard ways to characterize community-based individuals experiencing acute-LBP. The robust differences observed between these categorization approaches suggest that how we define acute-LBP severity is consequential; these different approaches may be used to improve the early identification of factors potentially contributing to the development of chronic-LBP.

Evidence of MRI image features and inflammatory biomarkers association with low back pain in patients with lumbar disc herniation

BACKGROUND CONTEXT

While MRI image features and inflammatory biomarkers are frequently used for guiding treatment decisions in patients with lumbar disc herniation (LDH) and low back pain (LBP), our understanding of the connections between these features and LBP remains incomplete. There is a growing interest in the potential significance of MRI image features and inflammatory biomarkers, both for quantification and as emerging therapeutic tools for LBP.

PURPOSE

To investigate the evidence supporting MRI image features and inflammatory biomarkers as predictors of LBP and to determine their relationship with pain intensity.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

All consecutive patients with LDH who underwent discectomy surgery at our institution from February 2020 to June 2023 at the author's institution were included.

OUTCOME MEASURES

MRI image features in discogenic, osseous, facetogenic, and paraspinal muscles, as well as inflammatory biomarkers in serum (including CRP (C-reactive protein), ESR (erythrocyte sedimentation rate), PCT (procalcitonin), TNF (tumor necrosis factor), interleukin-1 beta (IL-1β), and IL-6), and paraspinal muscles (including TNF, IL-1β, IL-6, IL-10, and transforming growth factor beta 1 (TGF-β1)).

METHODS

A series of continuous patients diagnosed with LDH were categorized into acute LBP (<12 weeks), chronic LBP (≥12 weeks), and nonLBP groups. MRI image features and inflammatory biomarkers relation to pain intensity was assessed using the independent t-test, Chi-squared tests, Spearman rank correlation coefficient, and logistic regression test.

RESULTS

Compared to the nonLBP group, the chronic LBP group exhibited a higher incidence of intervertebral disc (IVD) degeneration (≥ grade 3) and high-fat infiltration in paraspinal muscles, alongside a significant reduction in the cross-sectional area (CSA) and fatty degeneration of the multifidus muscle. Furthermore, there was a greater expression of IL-6 in serum and TNF in paraspinal muscles in the chronic LBP group and a greater expression of CRP and IL-6 in serum and TNF in paraspinal muscles in the acute LBP group. CSA and fatty degeneration of multifidus muscle were moderately negatively correlated with chronic LBP scores. The expression of TNF and IL-6 in serum and the expression of TNF in the multifidus muscle were moderately correlated with preoperative LBP. IVD degeneration and high-fat infiltration were identified as risk factors for chronic LBP.

CONCLUSION

The results provide evidence that IVD degeneration, high-fat infiltration, and the reduction of CSA in paraspinal muscles were associated with the development of chronic LBP in patients with LDH, and these associations are linked to inflammatory regulation. This deepens our understanding of the etiology and pathophysiology of LBP, potentially leading to improved patient stratification and more targeted interventions.

Poor lumbar spine coordination in acute low back pain predicts persistent long-term pain and disability

PURPOSE

Sitting balance on an unstable surface requires coordinated out-of-phase lumbar spine and provides sufficient challenge to expose quality of spine control. We investigated whether the quality of spine coordination to maintain balance in acute low back pain (LBP) predicts recovery at 6 months.

METHODS

Participants in an acute LBP episode (n = 94) underwent assessment of sitting balance on an unstable surface. Seat, hip and spine (lower lumbar, lumbar, upper lumbar, thoracic) angular motion and force plate data were recorded. Coordination between the seat and hip/spine segments to maintain balance was quantified in the frequency domain to evaluate coordination (coherence) and relative timing (phase angle: in-phase [segments move together]; out-of-phase [segments move opposite]). Center of pressure (CoP) and upper thorax motion assessed overall balance performance. Hip and spine coordination with the seat were compared between those who did not recover (increased/unchanged pain/disability), partially recovered (reduced pain/disability) or recovered (no pain and disability) at 6 months.

RESULTS

In both planes, coherence between the seat and lower lumbar spine was lower (and in-phase-unhelpful for balance) at baseline in those who did not recover than those who recovered. Coherence between the seat and hip was higher in partially recovered in both planes, suggesting compensation by the hip. LBP groups had equal overall balance performance (CoP, upper thorax motion), but non-recovery groups used a less optimal strategy that might have consequences for long-term spine health.

CONCLUSION

These longitudinal data revealed that individuals with compromised contribution of the lumbar spine to the balance during unstable sitting during acute LBP are less likely to recover.

The association between inflammatory biomarkers and low back disorder: a systematic review and meta-analysis

INTRODUCTION

Low back disorder (LBD) is a major cause of disability worldwide. Inflammation results in proliferation of cytokines or consequent degradation products (collectively known as inflammatory biomarkers) that activate pain pathways which can result in non-specific LBD. This systematic review and meta-analysis aim to evaluate the relationship between inflammatory biomarkers and clinical outcomes in patients with LBD.

METHODS

The PRISMA guideline was followed for the systematic reivew. Three online databases were searched. Four RCTs and sixteen observational studies with 1142 LBD patients were analysed. The primary outcomes were back and leg pain scores, back-specific disability scores and expression of inflammatory biomarkers. Standardized mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to summarize the strength of evidence.

RESULTS

Four RCTs and sixteen observational studies were included in the analysis of 1142 patients with LBD. There was a statistically significant reduction in back pain score and IL-1 beta and increase in the expression of CTX-1 and IL-10 levels post treatment. There was a significant relationship between increase in the expression of MCP- and reduction in the expression of hsCRP with increase in back pain. Significant relationship was also observed between increase in the expression of MCP-1 and reduction in the expression of IL-6 with increase in leg pain. Increase in the expression of IL-8 and reduction in the expression of hsCRP was also associated with increased disability score.

CONCLUSION

Inflammatory biomarkers play a significant role in the pathogenesis of LBD. CTX-1, IL-10 and IL-1 beta may be responsible for the decrease in back pain scores post treatment. There is a relationship between MCP-1, IL-6, IL-8 and hsCRP with clinical and functional assessments for LBD. Further studies will improve understanding of the pathogenesis of LBD and aid in targeted management strategies.

Sleep as a prognostic factor in low back pain: a systematic review of prospective cohort studies and secondary analyses of randomized controlled trials

Sleep problems are common in individuals with low back pain (LBP) and sleep restriction seems to be associated with impaired pain processing. Our objective was to investigate whether sleep is associated with future LBP outcomes (i.e. pain intensity, disability, and recovery) in adults. We conducted a systematic review of prospective cohort studies and secondary analyses of randomized controlled trials (registration-PROSPERO CRD42022370781). In December 2022, we searched the MEDLINE, Embase, CINAHL, and PsycINFO databases. Fourteen studies, totaling 19 170 participants were included. Thirteen studies were rated as having high risk of bias (QUIPS tool). We used vote-counting and meta-analysis approaches to synthesize the data. We found associations between baseline sleep with future pain intensity, recovery, and between changes in sleep with changes in pain intensity, changes in disability, and recovery. We further synthesized outcomes as "overall LBP improvement" outcomes. Baseline poor sleep was moderately associated with non-improvement in LBP in the long-very long term (OR 1.55, 95% CI: 1.39 to 1.73; three studies providing unadjusted effect sizes), and non-improvement in sleep was largely associated with non-improvement in LBP in the short-moderate term (OR 3.45, 95% CI: 2.54 to 4.69; four studies providing unadjusted effect sizes). We found no association between baseline sleep with future disability and overall LBP improvement in the short-moderate term. Therefore, sleep may be a prognostic factor for pain intensity and recovery from LBP. All findings were supported by low to very low-quality evidence. Better-conducted studies are needed to strengthen our certainty about the evidence.

Characterization of pain-related behaviors in a rat model of acute-to-chronic low back pain: single vs. multi-level disc injury

Introduction

Low back pain is the most common type of chronic pain. We examined pain-related behaviors across 18 weeks in rats that received injury to one or two lumbar intervertebral discs (IVD) to determine if multi-level disc injuries enhance/prolong pain.

Methods

Twenty-three Sprague-Dawley adult female rats were used: 8 received disc puncture (DP) of one lumbar IVD (L5/6, DP-1); 8 received DP of two lumbar IVDs (L4/5 & L5/6, DP-2); 8 underwent sham surgery.

Results

DP-2 rats showed local (low back) sensitivity to pressure at 6- and 12-weeks post-injury, and remote sensitivity to pressure (upper thighs) at 12- and 18-weeks and touch (hind paws) at 6, 12 and 18-weeks. DP-1 rats showed local and remote pressure sensitivity at 12-weeks only (and no tactile sensitivity), relative to Sham DP rats. Both DP groups showed reduced distance traveled during gait testing over multiple weeks, compared to pre-injury; only DP-2 rats showed reduced distance relative to Sham DP rats at 12-weeks. DP-2 rats displayed reduced positive interactions with a novel adult female rat at 3-weeks and hesitation and freezing during gait assays from 6-weeks onwards. At study end (18-weeks), radiological and histological analyses revealed reduced disc height and degeneration of punctured IVDs. Serum BDNF and TNFα levels were higher at 18-weeks in DP-2 rats, relative to Sham DP rats, and levels correlated positively with remote sensitivity in hind paws (tactile) and thighs (pressure).

Discussion

Thus, multi-level disc injuries resulted in earlier, prolonged and greater discomfort locally and remotely, than single-level disc injury. BDNF and TNFα may have contributing roles.

Sex Differences in the Serum Proteomic Profile During Acute Low Back Pain-A Preliminary Study of the Relationship to Future Low Back Pain

The molecular processes driving the transition from acute to chronic low back pain (LBP) remain poorly understood and are likely to be sexually dimorphic. This study aimed to explore sex differences in the serum proteomic profile of people experiencing an acute LBP episode and determine if serum protein concentrations were associated with three-month outcome. Serum samples were collected through venepuncture from 30 female and 29 male participants experiencing an acute LBP episode. Serum samples underwent trypsin digestion and fractionation using hydrophobic interaction chromatography and were then analysed using mass-spectrometry. Mass-spectrometry spectra were searched in the Swissprot database for protein identification. Sex differences in protein abundance changes were evident upon inspection of fold changes. Multivariable data analysis identified 21 serum proteins during the acute episode that correctly classified 93% of males and 23 serum proteins that correctly classified 90% of females with ongoing LBP at 3 months. Pathway analysis suggested the differentially expressed proteins during acute LBP were frequently involved in immune, inflammatory, complement, or coagulation responses. This data provides preliminary evidence that biological processes during an acute LBP episode may contribute to the resolution, or persistence, of LBP symptoms at 3 months, however, these processes differ between males and females. PERSPECTIVE: Differential expression of serum proteins was observed between male and female participants during an acute LBP episode. This preliminary work provides a foundation for future research targeting distinct immune system processes in males and females that may interfere with the transition from acute to chronic LBP.

Characterizing Acute Low Back Pain in a Community-Based Cohort

Acute low back pain (LBP) is a common experience, however, the associated pain severity, pain frequency, and characteristics of individuals with acute LBP in community settings have yet to be well understood. In this manuscript, three acute LBP severity categorization definitions were used based on LBP frequency combined with either 1) pain impact frequency (impact-based) or 2) pain intensity (intensity-based), as well as LBP pain interference frequency (interference only-based) severity categories. The purpose of this manuscript is to describe and then compare these acute LBP severity groups in the following characteristics: 1) sociodemographic, 2) general and physical health, and 3) psychological. This cross-sectional study used baseline data from 131 community-based participants with acute LBP (<4 weeks duration before screening and ≥30 pain-free days before acute LBP onset). Descriptive associations were calculated as prevalence ratios for categorical variables and Hedges' g for continuous variables. Our analyses identified several large associations for impact-based and intensity-based categories with global mental health, global physical health, STarT Back Screening Tool risk category, and general health. Larger associations were found with social constructs (racially and ethnically minoritized, performance of social roles, and isolation) when using the intensity-based versus impact-based categorization. The interference-based category did not capture as much variability between acute LBP severity categories. This study adds to the literature by providing standard ways to characterize community-based individuals experiencing acute LBP. The robust differences observed between these categorization approaches suggest that how we define acute LBP severity is consequential; these different approaches may be used to improve the early identification of factors potentially contributing to the development of chronic LBP.

Transition from Acute to Chronic Low Back Pain in a Community-Based Cohort

The transition from acute to chronic low back pain (LBP) in community settings has yet to be well understood. We recruited n=131 participants with acute LBP from the community and followed them for 3 and 6-month outcomes. Acute LBP was defined by a duration of < 4 weeks, and participants must have reported a 30-day LBP-free period before the current acute episode. Chronic LBP was defined as pain most or every day over the past 3 months. Baseline psychological, social, and demographic factors were examined as predictors of transition to chronic LBP at 3 months or continuation of chronic LBP at 6 months. The transition from acute to chronic LBP at 3 months was 32.2% ( 38/118). At 6 months, 80.7% (25/111) of participants who transitioned at 3 months continued to have chronic LBP. At 6 months, participants who identified as Black or African American were more likely than white participants to transition to chronic LBP (RR=1.76, 95% CI 1.05, 2.95) and more likely to continue to have chronic LBP (RR=2.19, 95% CI 1.14, 4.21). Those classified at baseline by both LBP most or every day and intensity of at least 30/100 were more likely to transition to chronic LBP (RR=3.13, 95% CI 1.84, 5.30) and continue to have chronic LBP at 6 months (RR=2.58, 95% CI 1.43, 4.16). The STarT Back Screening Tool and the OSPRO-YF were associated with the transition to chronic LBP at 3 months and continuation at 6 months. Participants with higher PROMIS General Health and PROMIS Physical Health scores were less likely to transition to chronic LBP or continue to have chronic LBP at 6 months. These findings identify factors of acute LBP in the community that may predict the transition to chronic LBP. Larger studies are needed to confirm these findings and better understand the mechanisms driving the transition to chronic LBP.

Association between dietary inflammatory index and musculoskeletal disorders in adults

This research investigated how the Dietary Inflammatory Index (DII) related to musculoskeletal issues in adults. It used a cross-sectional design with a sample of 3477 female and 3572 male participants aged 35 to 65 from the Ravansar Non-Communicable Diseases cohort study in western Iran. The DII is calculated from a Food Frequency Questionnaire (FFQ) to measure dietary intake. Musculoskeletal disorders including back pain, back pain/stiffness, joint pain, and joint pain/stiffness were evaluated by the RaNCD cohort study physician using a standard questionnaire. Logistic regression analysis examined the association between DII and musculoskeletal disorders. The findings demonstrated a positive association between higher DII scores and back pain/stiffness (OR 1.32, 95% CI 1.04-1.73, P = 0.047). Furthermore, DII displayed a significant association with a heightened odd to joint pain (OR 1.26, CI 1.10-1.46) when compared to those with lower DII scores (Q3 vs. Q1). After adjusting for cofounding factors, the Q3 DII quintile participants showed a 44% higher odd of experiencing joint pain/stiffness (OR 1.44, CI 1.01-2.05, P = 0.047). However, the study found no significant association between back pain and DII (P > 0.05). In conclusion, the research suggests that consuming a pro-inflammatory diet might be linked to developing musculoskeletal issues in adults.

Predicting chronic postsurgical pain: current evidence and a novel program to develop predictive biomarker signatures

ABSTRACT

Chronic pain affects more than 50 million Americans. Treatments remain inadequate, in large part, because the pathophysiological mechanisms underlying the development of chronic pain remain poorly understood. Pain biomarkers could potentially identify and measure biological pathways and phenotypical expressions that are altered by pain, provide insight into biological treatment targets, and help identify at-risk patients who might benefit from early intervention. Biomarkers are used to diagnose, track, and treat other diseases, but no validated clinical biomarkers exist yet for chronic pain. To address this problem, the National Institutes of Health Common Fund launched the Acute to Chronic Pain Signatures (A2CPS) program to evaluate candidate biomarkers, develop them into biosignatures, and discover novel biomarkers for chronification of pain after surgery. This article discusses candidate biomarkers identified by A2CPS for evaluation, including genomic, proteomic, metabolomic, lipidomic, neuroimaging, psychophysical, psychological, and behavioral measures. Acute to Chronic Pain Signatures will provide the most comprehensive investigation of biomarkers for the transition to chronic postsurgical pain undertaken to date. Data and analytic resources generatedby A2CPS will be shared with the scientific community in hopes that other investigators will extract valuable insights beyond A2CPS's initial findings. This article will review the identified biomarkers and rationale for including them, the current state of the science on biomarkers of the transition from acute to chronic pain, gaps in the literature, and how A2CPS will address these gaps.

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.

Changes of the posterior paraspinal and psoas muscle in patients with low back pain: a 3-year longitudinal study

PURPOSE

This study aimed to investigate the changes of the posterior paraspinal muscles (PPM) and psoas muscle in patients with low back pain (LBP) over time.

METHODS

Patients with LBP who had a repeat lumbar MRI with a minimum of 3-years apart at a tertiary referral center were analyzed. MRI-based quantitative assessments of the PPM and the psoas muscle were conducted for the baseline and follow-up MRI. The cross sectional area (CSA), the functional cross sectional area (fCSA) and the fat area (FAT) were calculated using a dedicated software program. The fatty infiltration (FI,%) of the regions of interest was calculated. Differences between the 1st and 2nd MRI were calculated for all assessed muscular parameters.

RESULTS

A total of 353 patients (54.4%female) with a median age of 60.1 years and BMI of 25.8 kg/m2 at baseline were analyzed. The mean time between the 1st and 2nd MRI was 3.6 years. The fCSAPPM declined in both sexes significantly from the 1st to the 2nd MRI, whereas the FATPPM increased. In line with this result, the FIPPM increased in both males (29.9%) and females (19.4%). Females had a higher FIPPM and FIPsoas than males in both MRIs. In females, no significant changes were found for the psoas muscle. The CSAPsoas and fCSAPsoas in males were significantly smaller in the 2nd MRI. With increasing age, a significant trend in a decrease in ∆FIPPM was observed for both sexes.

CONCLUSION

The study revealed significant quantitatively muscular changes in males and females, especially in the posterior paraspinal muscles in only three years' time.

Systemic pro- and anti-inflammatory profiles in acute non-specific low back pain: An exploratory longitudinal study of the relationship to six-month outcome

OBJECTIVES

Pro-inflammatory molecules are thought to underpin the development of chronic low back pain (LBP). Although research has begun to explore the association between pro-inflammatory molecules in acute LBP and long-term outcome, no study has explored the role of anti-inflammatory molecules. We aimed to explore whether levels of systemic pro- and anti-inflammatory molecules 1) changed over a period of six months from the onset of acute LBP; 2) differed between people who were recovered (N = 11) and unrecovered (N = 24) from their episode of LBP at six months; 3) baseline psychological factors were related to inflammatory molecule serum concentrations at baseline, three and six months.

METHODS

We retrospectively included participants with acute LBP included from a larger prospective trial and examined blood samples for the measurement of pro- and anti-inflammatory molecules and measures of pain, disability, and psychological factors at baseline, three and six months.

RESULTS

The serum concentrations of pro- and anti-inflammatory molecules did not differ over time when compared between participants who recovered and those who did not recover at six-month follow-up. At three months, the unrecovered group had higher interleukin (IL)-8 and IL-10 serum concentrations than the recovered group. Baseline psychological factors were not related to inflammatory molecules at any time point.

DISCUSSION

This exploratory study showed that levels of systemic inflammatory molecules did not change over the course of LBP, irrespective of whether people were recovered or unrecovered at six months. There was no relationship between acute-stage psychological factors and systemic inflammatory molecules. Further investigation is needed to elucidate the contribution of pro- and anti-inflammatory molecules to long-term LBP outcome.

Analysis of intervertebral disc CCR6 and IL-6 gene levels with short-term postoperative low back pain after spinal fusion in lumbar degenerative disease

Background

Previous studies have reported that specific pro-inflammatory cytokines or chemokines are more highly expressed in painful than in nonpainful intervertebral discs (IVDs). However, few studies have investigated their correlation with postsurgical outcomes or the relationship between postoperative pain and inflammatory cytokines in IVDs. Thus, the present study examined the correlation among the gene expression levels of pro-inflammatory cytokines and chemokines in IVD tissues removed during surgery and low back pain (LBP), leg pain (LP), and leg numbness (LN) at one year after spinal fusion surgery in patients with a lumbar degenerative disease (LDD).

Methods

Chemokine and cytokine gene expression levels were measured in IVD samples from 48 patients with LDD. The associations between chemokine and cytokine gene expression levels and pain intensity (numeric rating scale [NRS]) were also analyzed. A correlation analysis was performed between gene expression in each IVD and preoperative and postoperative pain intensity.

Results

In the preoperative analysis, CCR6 was associated with NRSLBP (r = -0.291, P = 0.045). Postoperative pain analysis revealed correlations between postoperative NRSLBP and CCR6 (r = -0.328, P = 0.023) and between postoperative NRSLBP and IL-6 (r = -0.382, P = 0.007). Furthermore, patients with high postoperative LBP intensity (NRSLBP ≥ 7) also had high LBP intensity (NRSLBP ≥ 6) before surgery, and a correlation was observed (r = 0.418, P = 0.003). None of the gene mRNAs correlated with NRSLP or NRSLN, respectively.

Conclusions

CCR6 and IL-6 gene expression in the IVD was associated with postoperative LBP intensity and may indicate a need for postoperative pain management.

Genetic impact of blood C-reactive protein levels on chronic spinal & widespread pain

PURPOSE

Causal mechanisms underlying systemic inflammation in spinal & widespread pain remain an intractable experimental challenge. Here we examined whether: (i) associations between blood C-reactive protein (CRP) and chronic back, neck/shoulder & widespread pain can be explained by shared underlying genetic variants; and (ii) higher CRP levels causally contribute to these conditions.

METHODS

Using genome-wide association studies (GWAS) of chronic back, neck/shoulder & widespread pain (N = 6063-79,089 cases; N = 239,125 controls) and GWAS summary statistics for blood CRP (Pan-UK Biobank N = 400,094 & PAGE consortium N = 28,520), we employed cross-trait bivariate linkage disequilibrium score regression to determine genetic correlations (rG) between these chronic pain phenotypes and CRP levels (FDR < 5%). Latent causal variable (LCV) and generalised summary data-based Mendelian randomisation (GSMR) analyses examined putative causal associations between chronic pain & CRP (FDR < 5%).

RESULTS

Higher CRP levels were genetically correlated with chronic back, neck/shoulder & widespread pain (rG range 0.26-0.36; P ≤ 8.07E-9; 3/6 trait pairs). Although genetic causal proportions (GCP) did not explain this finding (GCP range - 0.32-0.08; P ≥ 0.02), GSMR demonstrated putative causal effects of higher CRP levels contributing to each pain type (beta range 0.027-0.166; P ≤ 9.82E-03; 3 trait pairs) as well as neck/shoulder pain effects on CRP levels (beta [S.E.] 0.030 [0.021]; P = 6.97E-04).

CONCLUSION

This genetic evidence for higher CRP levels in chronic spinal (back, neck/shoulder) & widespread pain warrants further large-scale multimodal & prospective longitudinal studies to accelerate the identification of novel translational targets and more effective therapeutic strategies.

Role of C-reactive protein in the bone marrow of Modic type 1 changes

Modic type 1 changes (MC1) are vertebral bone marrow lesions and associate with low back pain. Increased serum C-reactive protein (CRP) has inconsistently been associated with MC1. We aimed to provide evidence for the role of CRP in the tissue pathophysiology of MC1 bone marrow. From 13 MC1 patients undergoing spinal fusion at MC1 levels, vertebral bone marrow aspirates from MC1 and intrapatient control bone marrow were taken. Bone marrow CRP, interleukin (IL)-1, and IL-6 were measured with enzyme-linked immunosorbent assays; lactate dehydrogenase (LDH) was measured with a colorimetric assay. CRP, IL-1, and IL-6 were compared between MC1 and control bone marrow. Bone marrow CRP was correlated with blood CRP and with bone marrow IL-1, IL-6, and LDH. CRP expression by marrow cells was measured with a polymerase chain reaction. Increased CRP in MC1 bone marrow (mean difference: +0.22 mg CRP/g, 95% confidence interval [CI] [-0.04, 0.47], p = 0.088) correlated with blood CRP (r = 0.69, p = 0.018), with bone marrow IL-1β (ρ = 0.52, p = 0.029) and IL-6 (ρ = 0.51, p = 0.031). Marrow cells did not express CRP. Increased LDH in MC1 bone marrow (143.1%, 95% CI [110.7%, 175.4%], p = 0.014) indicated necrosis. A blood CRP threshold of 3.2 mg/L detected with 100% accuracy increased CRP in MC1 bone marrow. In conclusion, the association of CRP with inflammatory and necrotic changes in MC1 bone marrow provides evidence for a pathophysiological role of CRP in MC1 bone marrow.

Correlation between inflammatory cytokine expression in paraspinal tissues and severity of disc degeneration in individuals with lumbar disc herniation

PURPOSE

Previous animal studies have discovered dysregulation of the local inflammatory state as a novel mechanism to explain structural changes in paraspinal muscles in association with disc degeneration. This study aimed to determine whether the expression of inflammatory genes in the multifidus muscle (MM) differs between individuals with disc degeneration and non-degeneration, which may cause changes in the cross-sectional area (CSA) of paraspinal muscles and clinical outcomes.

METHODS

Muscles were procured from 60 individuals undergoing percutaneous endoscopic lumbar discectomy for lumbar disc herniation (LDH). Total and functional CSAs and fatty degeneration of paraspinal muscles on ipsilateral and unilateral sides were measured. Gene expression was quantified using qPCR assays. Paired t-test and Pearson's correlation analysis were used to compare the mean difference and associations, respectively.

RESULTS

There were significant differences in total CSAs of paraspinal muscles and functional CSA and fatty degeneration of MM between ipsilateral and unilateral sides. Participants in the disc degeneration group displayed higher fat infiltration in MM. The expression of TNF was moderately correlated with total CSAs of paraspinal muscles and functional CSA and fatty degeneration of MM. The expression of IL-1β was strongly correlated with the total and functional CSA of MM. The expression of TGF-β1 was moderately correlated with the functional CSA of MM. The expression of TNF, IL-1β, and TGF-β1 was moderate to strongly correlated with clinical outcomes.

CONCLUSION

The results show that there were differences in the characteristics of paraspinal muscles between the ipsilateral and unilateral sides, which were affected by disc degeneration and the degree of fat infiltration. High-fat filtration and reduction of CSA of MM are associated with inflammatory dysfunction. There was evidence of a dysregulated inflammatory profile in MM in individuals with poor clinical outcomes.

Associations among acute and chronic musculoskeletal pain, sleep duration, and C-reactive protein (CRP): A cross-sectional study of the UK biobank dataset

Both musculoskeletal pain and sleep disturbances are major health problems worldwide. Literature suggests that the two are reciprocally related and both may be associated with changes in C-reactive protein (CRP) levels. However, the relationships among musculoskeletal pain, sleep duration, and CRP remain unclear. In this cross-sectional study, we investigated the relationship between acute and chronic musculoskeletal pain, sleep, and inflammation using the data from the initial visit of the UK Biobank. 17,642 individuals with chronic musculoskeletal pain, 11,962 individuals with acute musculoskeletal pain, and 29,604 pain-free controls were included in the analysis. In addition, we validated the findings using data from the second visit assessment of the UK Biobank. We found that 1) chronic pain was associated with higher CRP levels compared to both acute pain and the pain-free controls; 2) chronic pain was associated with a lower sleep score (a measurement of sleep patterns), compared to acute pain and the pain-free controls; and acute pain was associated with lower sleep scores compared to the controls; 3) there was a significant negative association between the sleep score and CRP; 4) CRP may partially mediate the association between chronic pain and decreased sleep score. However, the effect size of the mediation was rather small, and the pathophysiological significance remains uncertain. Further validation is needed. These findings were partly replicated in the UK Biobank second visit assessment cohort with a smaller sample size. Our findings, which are based on the large UK Biobank dataset, support the interplay between musculoskeletal pain, sleep patterns, and the potential mediating role of CRP on this reciprocal relationship.

Cortical function and sensorimotor plasticity are prognostic factors associated with future low back pain after an acute episode: the Understanding persistent Pain Where it ResiDes prospective cohort study

ABSTRACT

Predicting the development of chronic low back pain (LBP) at the time of an acute episode remains challenging. The Understanding persistent Pain Where it ResiDes study aimed to identify neurobiological and psychological risk factors for chronic LBP. Individuals with acute LBP (N = 120) participated in a prospective cohort study with 6-month follow-up. Candidate predictors were selected from the neurobiological (eg, sensorimotor cortical excitability assessed by sensory and motor-evoked potentials and brain-derived neurotrophic factor genotype), psychological (eg, depression and anxiety), symptom-related (eg, LBP history), and demographic domains. Analyses involved multivariable linear regression models with pain intensity or disability degree as continuous variables. Secondary analyses involved a multivariable logistic model with the presence of LBP at 6 months (thresholding pain intensity and disability degree) as a dichotomous variable. Lower sensory cortex and corticomotor excitability, higher baseline pain intensity, higher depression, stress, and pain catastrophizing were the strongest predictors ( R2 = 0.47) of pain intensity at 6 months. Older age and higher pain catastrophizing were the strongest predictors ( R2 = 0.30) of disability at 6 months. When the LBP outcome was dichotomised, sensory cortex and corticomotor excitability, brain-derived neurotrophic factor genotype, depression and anxiety, LBP history and baseline pain intensity, discriminated between those who did and did not report LBP at 6 months (C-statistic 0.91). This study identifies novel risk factors for the development of future LBP. Neurobiological risk factors, when added to a multivariable linear regression model, explained a further 15% of the variance in the 6-month pain intensity.

The association of biomarkers with pain and function in acute and subacute low back pain: a secondary analysis of an RCT

BACKGROUND

Low back pain (LBP) is a common musculoskeletal condition and a major cause of disability worldwide. Previous studies have found associations of biomarkers with pain and pain-related disability in LBP patients. This study aimed to explore the association between serum biomarkers and pain and disability in patients with acute or subacute axial LBP.

METHODS

This study was ancillary to a parent randomized controlled trial. Enrolled participants were randomized into three intervention groups: one of two types of spinal manipulation or medical care. In the parent study, 107 adults who experienced a new episode of LBP within 3 months prior to enrollment were recruited. For this study, 90 of these 107 participants consented to have blood samples obtained, which were drawn immediately before the beginning of treatment. Seven biomarkers were chosen based on previous literature and analyzed. Clinical outcomes were pain and Oswestry Disability Index (ODI) evaluated at baseline and 4 weeks. Spearman's |r| was used to study the association of initial levels of each biomarker with pain and ODI scores at baseline and with changes in outcome scores from baseline to 4 weeks (end of treatment) within each intervention group.

RESULTS

At baseline, 4 of 7 biomarkers had an association with pain that was |r| ≥ .20: neuropeptide Y (NPY) (r = 0.23, p = .028), E-Selectin (r = 0.22, p = .043), vitamin D ((r = - 0.32, p = .002), and c-reactive protein (CRP) (r = 0.37, p = .001). No baseline biomarker had an association with disability that was |r| ≥ 0.20. For the correlations of baseline biomarkers with 4-week change in outcomes, vitamin D showed a correlation with change in disability and/or pain (|r| ≥ 0.20, p > .05) in manipulation-related groups, while CRP, NPY, and E-selectin along with TNFα, Substance P and RANTES showed at least one correlation with change in pain or disability (|r| ≥ 0.20, p > .05) in at least one of the treatment groups.

CONCLUSIONS

In 90 LBP patients, the analyzed biomarkers, especially vitamin D, represent a small set of potential candidates for further research aimed at individualizing patient care. Overall, the associations investigated in the current study are an initial step in identifying the direct mechanisms of LBP and predicting outcomes of manipulation-related treatments or medical care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01211613, Date of Registration: September 29, 2010, https://clinicaltrials.gov/ct2/show/NCT01211613?term=schneider&cond=Low+Back+Pain&cntry=US&state=US%3APA&draw=2&rank=1.

Immune-inflammatory and hypothalamic-pituitary-adrenal axis biomarkers are altered in patients with non-specific low back pain: A systematic review

This systematic review aimed to investigate immune-inflammatory and hypothalamic-pituitary-adrenal (HPA) axis biomarkers in individuals with non-specific low back pain (NSLBP) compared to healthy control. The search was performed in five databases until 4 November 2021. Two reviewers independently conducted screenings, data extraction, risk of bias, and methodological quality assessment of 14 unique studies. All studies reported the source of the fluid analyzed: nine studies used serum, two used plasma, one used serum and plasma, and two studies used salivary cortisol. We found preliminary and limited evidence (only one study for each biomarker) of increased levels in growth differentiation factor 15 (GDF-15), interleukin-23 (IL-23), transforming growth factor–beta (TGF-β), and soluble tumor necrosis factor receptor 1 (sTNF-R1) in NSLBP. Inconsistent and limited evidence was identified for interleukin-10 (IL-10). Although C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor–alpha (TNF-α) levels appear to increase in NSLBP, only one study per each biomarker reported statistically significant differences. Interleukin-1 beta (IL-1β), interleukin-17 (IL-17), interferon gamma (IFN-γ), and high-sensitivity CRP (hsCRP) showed no significant differences. Regarding cortisol, one study showed a significant increase and another a significant decrease. More robust evidence between GDF-15, IL-23, TGF-β, and sTNF-R1 with NSLBP is needed. Moreover, contrary to the findings reported in previous studies, when comparing results exclusively with healthy control, insufficient robust evidence for IL-6, TNF-α, and CRP was found in NSLBP. In addition, cortisol response (HPA-related biomarker) showed a dysregulated functioning in NSLBP, with incongruent evidence regarding its directionality. Therefore, our effort is to find adjusted evidence to conclude which immune-inflammatory and HPA axis biomarkers are altered in NSLBP and how much their levels are affected.

Association of Biomarkers with Individual and Multiple Body Sites of Pain: The Johnston County Osteoarthritis Project

Introduction

Biochemical biomarkers may provide insight into musculoskeletal pain reported at individual or multiple body sites. The purpose of this study was to determine if biomarkers or pressure-pain threshold (PPT) were associated with individual or multiple sites of pain.

Methods

This cross-sectional analysis included 689 community-based participants. Self-reported symptoms (ie, pain, aching, or stiffness) were ascertained about the neck, upper back/thoracic, low back, shoulders, elbows, wrist, hands, hips, knees, ankles, and feet. Measured analytes included CXCL-6, RANTES, HA, IL-6, BDNF, OPG and NPY. A standard dolorimeter measured PPT. Logistic regression was used determine the association between biomarkers and PPT with individual and summed sites of pain.

Results

Increased IL-6 and HA were associated with knee pain (OR=1.30, 95% CI 1.03, 1.64) and (OR=1.32, 95% CI 1.01, 1.73) respectively; HA was also associated with elbow/wrist/hand pain (OR=1.60, 95% CI 1.22, 2.09). Those with increased NPY levels were less likely to have shoulder pain (OR=0.56, 95% CI 0.33, 0.93). Biomarkers HA (OR=1.50, 95% CI 1.07, 2.10), OPG (OR=1.74, 95% CI 1.00, 3.03), CXCL-6 (OR=1.75, 95% CI 1.02, 3.01) and decreased PPT (OR=3.97, 95% CI 2.22, 7.12) were associated with multiple compared to no sites of pain. Biomarker HA (OR=1.57, 95% CI 1.06, 2.32) and decreased PPT (OR=3.53, 95% CI 1.81, 6.88) were associated with multiple compared to a single site of pain.

Conclusion

Biomarkers of inflammation (HA, OPG, IL-6 and CXCL-6), pain (NPY) and PPT may help to understand the etiology of single and multiple pain sites.

Paraspinal Muscle Health is Related to Fibrogenic, Adipogenic, and Myogenic Gene Expression in Patients with Lumbar Spine Pathology

BACKGROUND

Lumbar spine pathology is a common feature of lower back and/or lower extremity pain and is associated with observable degenerative changes in the lumbar paraspinal muscles that are associated with poor clinical prognosis. Despite the commonly observed phenotype of muscle degeneration in this patient population, its underlying molecular mechanisms are not well understood. The aim of this study was to investigate the relationships between groups of genes within the atrophic, myogenic, fibrogenic, adipogenic, and inflammatory pathways and multifidus muscle health in individuals undergoing surgery for lumbar spine pathology.

METHODS

Multifidus muscle biopsies were obtained from patients (n = 59) undergoing surgery for lumbar spine pathology to analyze 42 genes from relevant adipogenic/metabolic, atrophic, fibrogenic, inflammatory, and myogenic gene pathways using quantitative polymerase chain reaction. Multifidus muscle morphology was examined preoperatively in these patients at the level and side of biopsy using T2-weighted magnetic resonance imaging to determine whole muscle compartment area, lean muscle area, fat cross-sectional areas, and proportion of fat within the muscle compartment. These measures were used to investigate the relationships between gene expression patterns and muscle size and quality.

RESULTS

Relationships between gene expression and imaging revealed significant associations between decreased expression of adipogenic/metabolic gene (PPARD), increased expression of fibrogenic gene (COL3A1), and lower fat fraction on MRI (r = -0.346, p = 0.018, and r = 0.386, p = 0.047 respectively). Decreased expression of myogenic gene (mTOR) was related to greater lean muscle cross-sectional area (r = 0.388, p = 0.045).

CONCLUSION

Fibrogenic and adipogenic/metabolic genes were related to pre-operative muscle quality, and myogenic genes were related to pre-operative muscle size. These findings provide insight into molecular pathways associated with muscle health in the presence of lumbar spine pathology, establishing a foundation for future research that addresses how these changes impact outcomes in this patient population.

SYSTEMIC CYTOKINE LEVEL DIFFERENCES IN PATIENTS WITH CHRONIC MUSCULOSKELETAL SPINAL PAIN COMPARED TO HEALTHY CONTROLS AND ITS ASSOCIATION WITH PAIN SEVERITY: A SYSTEMATIC REVIEW

OBJECTIVE

Although there has been increasing interest in the role of systemic cytokines in chronic spinal pain (CSP), the evidence on their potential contribution is still unclear. Therefore, the current study systematically reviewed the evidence on systemic cytokine level differences between people with CSP compared to healthy controls (HCs) and the potential associations with pain severity.

METHODS

An electronic search was conducted on PubMed, Web of Science and Embase. All included studies were classified as observational studies, exploring the comparison between a CSP group and a HC group, and the association between systemic cytokine levels and pain severity.

RESULTS

Nine articles were included with a total sample of 400 CSP patients suffering from chronic whiplash associated disorder (CWAD) or chronic low back pain (CLBP). In CLBP, moderate evidence was found for elevated tumor necrosis factor (TNF) α, interleukin (IL) 6, IL-1 receptor antagonist (IL-1RA), and soluble TNF receptor (sTNF-R) type 2, for normal interferon (IFN) γ and IL-2 levels, and for reduced IL-10 levels. No association was found between pain severity and these cytokines in CLBP. In CWAD, moderate evidence was found for elevated CRP and evidence for changes in TNF-α was inconclusive. Evidence for the association between pain severity and CRP was limited, and there is probably no association between pain severity and TNF-α with limited evidence in CWAD.

CONCLUSIONS

Moderate evidence indicates the presence of systemic inflammation in CSP. Evidence regarding the association between pain severity and systemic cytokines is inconclusive and limited.

Relationship between systemic inflammation and recovery over 12 months after an acute episode of low back pain

BACKGROUND CONTEXT

Individual characteristics can influence outcomes after injury. Our previous work in individuals with early-acute low back pain (LBP) identified subgroups (clusters) with specific biopsychosocial features that recovered poorly or well by 6 months.

PURPOSE

This study extends on that work by revealing the short- and long-term trajectories of recovery and systemic inflammation of these participant clusters: (1) "inflammatory & poor sleep" (Cluster 1), "high TNF & depression" (Cluster 2), "high pain & high pain-related fear" (Cluster 3), and "low pain & low pain-related fear" (Cluster 4).

STUDY DESIGN/SETTING

Longitudinal cohort study.

PATIENT SAMPLE

Eighty-three individuals within 2 weeks of an acute episode of LBP - grouped into their a priori-defined cluster.

OUTCOME MEASURES

General participant characteristics (sex, age, body mass index, smoking history, previous LBP history); self-reported LBP (0-10 numerical rating scale, LBP-related disability (Roland-Morris Disability Questionnaire), depression (Center for Epidemiological Studies Depression Scale, pain catastrophizing (Pain Catastrophizing Scale), fear avoidance (Fear Avoidance Beliefs Questionnaire), pain self-efficacy (Pain Self-Efficacy Questionnaire), and sleep (Pittsburgh Sleep Quality Index); systemic inflammatory biomarkers (C-reactive protein [CRP], interleukin-6 [IL-6], interleukin-1β, tumor necrosis factor [TNF]).

METHODS

Participants provided blood for the measurement of CRP/cytokines, and completed questionnaires related to their pain/disability, psychological and sleep status. Blood measures were repeated 3-monthly for 9 months, and pain/disability were self-reported fortnightly for 12 months. Recovery (change in pain) and CRP/cytokines were longitudinally compared between clusters using mixed-models. Associations between baseline factors and follow-up CRP/cytokines levels were assessed with multiple regression.

RESULTS

Clusters 1 and 2 were associated, but oppositely, with recovery over the 12-months. Cluster 1 reported most recovery at every 3-monthly interval, whereas Cluster 2 reported least recovery. Cluster 1 had elevated CRP (and IL-6) at baseline that continued to decrease from 3 to 9 months. TNF was elevated early and persistently in Cluster 2. Baseline factors other than inflammation generally failed to predict follow-up inflammation.

CONCLUSIONS

Findings support the early role of CRP (and perhaps IL-6) in control of inflammation and recovery, and a pathological role of persistent TNF overexpression, which may be perpetuated by depressive-like behaviors.

Risk factors for low back pain outcome: Does it matter when they are measured?

BACKGROUND

The early identification of factors that increase risk of poor recovery from acute low back pain (LBP) is critical to prevent the transition to chronicity. Although most studies of risk factors for poor outcome in LBP tend to investigate the condition once it is already persistent, there is evidence to suggest that this differs from risk factors measured during the early-acute stage. This study aimed to identify early risk factors for poor outcome in the short- and long-term in individuals with acute LBP, and to compare this with factors identified at 3 months in the same cohort.

METHODS

One hundred and thirty-three individuals were recruited within 2 weeks of an acute LBP episode and completed questionnaires related to their sociodemographic, psychological, clinical and history/treatment status at baseline and 3 months later, and their pain-level fortnightly for 12 months.

RESULTS

Of the 133 participants recruited, follow-up data was provided by 120 at 3 months, 97 at 6 months, 85 at 9 months and 94 at 12 months. Linear regression identified various factors at baseline (acute phase) and 3 months later that predicted short- and long-term outcome (pain level, change in pain). Key findings were that: (1) depressive symptoms at baseline most consistently predicted worse outcome; (2) psychological factors in general at 3 months were more predictive of outcome than when measured at baseline; (3) early health care utilisation predicted better outcome, whereas use of pain medication later (3 months) predicted worse outcome; and (4) sex and BMI predicted outcome inconsistently over 12-months.

CONCLUSIONS

The results highlight the multidimensional nature of risk factors for poor outcome in LBP and the need to consider time variation in these factors.

Increased serum CXCL10 levels are associated with clinical severity and radiographic progression in patients with lumbar disc degeneration

BACKGROUND

Lumbar intervertebral degenerative disc disease (IDD) is a multifaceted progressive condition that commonly occurs in conjunction with lumbar disc herniation (LDH). CXCL10 mRNA appears to be increased in both IDD and LHD.

OBJECTIVE

This study was performed to identify the relationship between serum CXCL10 levels and disease severity in patients with IDD.

METHODS

136 IDD patients with low back pain, 127 asymptomatic volunteers and 120 healthy controls were enrolled. Serum CXCL10 protein concentrations were detected using commercial human CXCL10 ELISA Kits. Serum CXCL10 mRNA were examined using qRT-PCR. Clinical severity was assessed using the visual analog scale (VAS) and Oswestry Disability Index(ODI) scores. Radiographic severity was defined using the MRI-based Pfirrmann classification of disc degeneration. Receiver operating characteristic (ROC) curve analysis was used in estimating the correlation between CXCL10 and Pfirrmann grade. The cross-sectional area (CSA) of the lumbar multifidus muscle (LMM) and psoas major (PM) were calculated, and fat infiltration was evaluated by Ropponen-Kjaer criteria.

RESULTS

Serum CXCL10 concentrations were markedly raised in IDD patients with low back pain in contrast to asymptomatic individuals and healthy controls. Serum CXCL10 levels were positively associated with Pfirrmann grade. ROC curve analysis indicated that serum CXCL10 correlated well with Pfirrmann grade. In addition, serum CXCL10 concentrations were significantly higher in IDD patients with LMM and PM degeneration compared with IDD patients without degeneration. Increased CXCL10 levels positively correlated with VAS and ODI scores, as well as decreased CSA and fat filtration of the LMM and PM.

CONCLUSION

Increased serum CXCL10 levels correspond to clinical severity and radiographic progression in IDD patients.

Evaluation of hematological parameters related to systemic inflammation in acute and subacute/chronic low back pain

Aim: To compare the hematological parameters associated with systemic inflammation between acute and subacute/chronic nonspecific low back pain and to evaluate their diagnostic roles in relation to chronicity in low back pain. Materials & methods: This retrospective case-control study included 150 participants aged 18-65 years with acute nonspecific low back pain, 150 with subacute/chronic nonspecific low back pain, 150 as the control group. Results: Red cell distribution width was significantly higher in the subacute/chronic pain group compared with the acute pain group (p = 0.003), and had a poor diagnostic value for chronicity (cutoff: 11.95, p = 0.003). There were no significant differences in terms of other parameters (p > 0.05). Conclusion: Red cell distribution width has a poor diagnostic value for chronicity in nonspecific low back pain.

Identifying the most important confounders when assessing the association between low-grade systemic inflammation and musculoskeletal pain: A modified Delphi study

Objective

The association between low-grade systemic inflammation and musculoskeletal pain may be influenced by multiple factors. However, little is known about the relative importance of these factors, and few studies account for them. This Delphi study aimed to reach consensus on the most important confounders which influence the association between low-grade systemic inflammation and musculoskeletal pain.

Methods

The panel consisted of 48 experts. In Round 1, the experts proposed what they believed were important confounders. In Round 2, the experts indicated for each confounder whether they believed it was important (yes/no). At least 50% of experts had to indicate the confounder was important to be considered in the final round. In Round 3, the experts rated the importance of each confounder on a 7-point Likert scale. Consensus was reached if ≥75% of the experts considered the factor either extremely or moderately important.

Results

In Round 1, 120 confounders were proposed, which were synthesized into 38 distinct factors. In Round 2, 33 confounders met the criterion to be considered important. In Round 3, consensus was reached for 14 confounders: acute illness/trauma, immune disease, medication use, endocrine, nutritional, or metabolic disease, other musculoskeletal conditions, age, handling of blood samples, sex, cancer, body composition, pregnancy, cardiovascular disease, physical activity, and pain characteristics.

Conclusions

These findings provide insight in the complexity of the association between low-grade systemic inflammation and musculoskeletal pain. Some factors currently listed as confounders may be re-classified as moderators or mediators as insights progress.

Does the Interaction between Local and Systemic Inflammation Provide a Link from Psychology and Lifestyle to Tissue Health in Musculoskeletal Conditions?

Musculoskeletal conditions are known to involve biological, psychological, social and, often, lifestyle elements. However, these domains are generally considered in isolation from each other. This siloed approach is unlikely to be adequate to understand the complexity of these conditions and likely explains a major component of the disappointing effects of treatment. This paper presents a hypothesis that aims to provide a foundation to understand the interaction and integration between these domains. We propose a hypothesis that provides a plausible link between psychology and lifestyle factors with tissue level effects (such as connective tissue dysregulation/accumulation) in musculoskeletal conditions that is founded on understanding the molecular basis for interaction between systemic and local inflammation. The hypothesis provides plausible and testable links between mind and body, for which empirical evidence can be found for many aspects. We present this hypothesis from the perspective of connective tissue biology and pathology (fibrosis), the role of inflammation locally (tissue level), and how this inflammation is shaped by systemic inflammation through bidirectional pathways, and various psychological and lifestyle factors via their influence on systemic inflammation. This hypothesis provides a foundation for new consideration of the development and refinement of personalized multidimensional treatments for individuals with musculoskeletal conditions.

Do Markers of Inflammation and/or Muscle Regeneration in Lumbar Multifidus Muscle and Fat Differ Between Individuals with Good or Poor Outcome Following Microdiscectomy for Lumbar Disc Herniation?

STUDY DESIGN

Observational study.

OBJECTIVE

The aim of this study was to evaluate whether inflammatory and/or muscle regeneration markers in paraspinal tissues (multifidus muscle/fat) during microdiscectomy surgery in patients with lumbar disc herniation (LDH) with radiculopathy, differ between individuals with good or poor outcome.

SUMMARY OF BACKGROUND DATA

Structural back muscle changes, including fat infiltration, muscle atrophy, and fiber changes, are ubiquitous with LBP and are thought to be regulated by inflammatory and regeneration processes. Muscle changes might be relevant for recovery after microdiscectomy, but a link between expression of inflammatory and muscle regeneration genes in paraspinal tissues and clinical outcome has not been tested.

METHOD

Paraspinal tissues from deep multifidus muscles and fat (intramuscular, sub-cutaneous, epidural) were harvested from twenty-one patients with LDH undergoing microdiscectomy surgery. Quantitative polymerase chain reaction (qPCR) measured expression of 10 genes. Outcome was defined as good (visual analogue scale (VAS) low back pain (LBP)+) or poor (VAS LBP-) by an improvement of >33% or ≤33% on the pain VAS, respectively. Good functional improvement was defined as 25% improvement on the physical functioning scale (PFS).

RESULTS

Brain-derived neurotrophic factor expression in deep multifidus was 91% lower (P = 0.014) in the VAS LBP- than VAS LBP+ group. Expression of interleukin-1β in subcutaneous fat was 48% higher (P = 0.026) in the VAS LBP- than VAS LBP+ group. No markers differed based on PFS.

CONCLUSION

Results show a relationship between impaired muscle regeneration profile in multifidus muscle and poor outcome following microdiscectomy for LDH. Inflammatory dysregulation in subcutaneous fat overlying the back region might predict poor surgical outcome.Level of Evidence: 4.

Circulating Adipokines in Predicting the Transition from Acute to Persistent Low Back Pain

OBJECTIVES

Cytokines such as tumor necrosis factor (TNF) contribute to the transition from acute to persistent pain. Despite increasing incidence of obesity and its linkage with chronic pain and inflammation, cytokines predominantly produced by adipose tissue (adipokines) have received little attention. Here we aimed to explore the longitudinal trajectory of adipokines from the onset of acute low back pain (LBP) and identify combinations of adipokines and/or other features that predict outcome.

METHODS

Individuals with acute LBP (less than two weeks after onset) who had either recovered (no pain, N = 15) or remained unrecovered (no reduction/increase in pain, N = 13) at six months and 15 controls were retrospectively selected from a larger prospective cohort. Participants provided blood for the measurement of TNF, interleukin-6 (IL-6), resistin, visfatin, adiponectin, leptin, and C-reactive protein (CRP), and completed questionnaires related to pain/disability, depression, and sleep at baseline. LBP participants repeated measurements at six months.

RESULTS

Compared with controls, acute LBP individuals had higher TNF and CRP but lower adiponectin. In LBP, unrecovered individuals had higher TNF at both time points, but lower CRP at baseline and leptin at six months. Although combined low CRP, high TNF, and depressive symptoms at baseline predicted poor recovery, the primary adipokines leptin, resistin, visfatin, and adiponectin did not.

CONCLUSIONS

Primary adipokines did not add to the prediction of poor LBP outcome that has been identified for the combination of low CRP, high TNF, and depressive symptoms in acute LBP. Whether adipokines play a role in LBP persistence in overweight/obese individuals requires investigation.

Serum biomarkers for Modic changes in patients with chronic low back pain

PURPOSE

Lumbar Modic change (MC) can serve as a diagnostic marker as well as an independent source of chronic low back pain (CLBP). This study aimed to test for the existence of serum biomarkers in CLBP patients with MC.

METHODS

Age- and sex-matched CLBP patients with confirmed MC on lumbar MRI (n = 40) and pain-free controls (n = 40) were assessed. MC was classified into M1, predominating M1, predominating M2 and M2. MC volumes were calculated. Fasting blood samples were assessed for inflammatory mediators, signalling molecules, growth factors and bone turnover markers. Serum concentrations of 46 biomarkers were measured.

RESULTS

Median concentrations of interleukin (IL)-15 (p < 0.001), IL-8 (p < 0.001), tumour necrosis factor (TNF)-alpha (p < 0.001), Eotaxin-1 (p < 0.05), Eotaxin-3 (p < 0.001), monocyte chemotactic protein (MCP)-1 (p < 0.05), macrophage inflammatory protein (MIP)-1alpha (p < 0.01), TEK receptor tyrosine kinase (Tie)-2 (p < 0.001), vascular cell adhesion molecule (VCAM)-1 (p < 0.001), RANTES (p < 0.001), C telopeptide of type I collagen (CTX)-1 (p < 0.001), vascular endothelial growth factor (VEGF)-C (p < 0.001), VEGF-D (p < 0.05), fms-related tyrosine kinase (Flt)-1 (p < 0.01) and intercellular adhesion molecule (ICAM)-1 (p < 0.01) were significantly higher among controls. IL-1sRII (23.2 vs. 15.5 ng/ml, p < 0.001) and hepatocyte growth factor (HGF)-1 (169 vs. 105 pg/ml, p < 0.01) concentrations were significantly higher among patients. Type or volume of MC was not associated with biomarker concentrations.

CONCLUSIONS

This is the first study to assess the blood serum biomarker profile in individuals with CLBP with MC. Several biomarkers were suppressed, while two markers (IL-1sRII and HGF) were elevated among MC patients, irrespective of MC type or size, with CLBP compared with asymptomatic controls.

Effects of spinal manipulative therapy on inflammatory mediators in patients with non-specific low back pain: a non-randomized controlled clinical trial

Background

The inflammatory profiles of patients with acute and chronic nonspecific low back pain (LBP) patients are distinct. Spinal manipulative therapy (SMT) has been shown to modulate the production of nociceptive chemokines differently in these patient cohorts. The present study further investigates the effect(s) of SMT on other inflammatory mediators in the same LBP patient cohorts.

Methods

Acute (n = 22) and chronic (n = 25) LBP patients with minimum pain scores of 3 on a 10-point numeric scale, and asymptomatic controls (n = 24) were recruited according to stringent exclusion criteria. Blood samples were obtained at baseline and after 2 weeks during which patients received 6 SMTs in the lumbar or lumbosacral region. The in vitro production of tumor necrosis factor (TNFα), interleukin-1 β (IL-1β), IL-6, IL-2, interferon ɣ (IFNɣ), IL-1 receptor antagonist (IL-1RA), TNF soluble receptor type 2 (sTNFR2) and IL-10 was determined by specific immunoassays. Parametric as well as non-parametric statistics (PAST 3.18 beta software) was used to determine significance of differences between and within study groups prior and post-SMT. Effect size (ES) estimates were obtained using Cohen’s d.

Results

Compared with asymptomatic controls, SMT-related change scores were significant (P = 0.03–0.01) in reducing the production levels of TNFα in both patient cohorts and those of IL-6, IFNɣ and sTNFR2 (P = 0.001–0.02) in patients with chronic LBP. Above-moderate to large ES (d > 0.6–1.4) was observed for these mediators. Compared with respective baselines, a significant post-SMT reduction (P = 0.01) of IL-6 production was detected only in patients with chronic LBP while a significant increase of IL-2 production (P = 0.001 vs. control, and P = 0.004 vs. chronic LBP group) and a large ES (d = 0.87) were observed in patients with acute LBP. Pain and disability scores declined significantly (P < 0.001) in all LBP patients, and were positively correlated (P = 0.03) with IFNɣ and IL-2 levels in the acute LBP cohort.

Conclusion

The short course of SMT treatments of non-specific LBP patients resulted in significant albeit limited and diverse alterations in the production of several of the mediators investigated in this study. This exploratory study highlights the potential of SMT to modulate the production of inflammatory components in acute and chronic non-specific LBP patients and suggests a need for further, randomized controlled clinical trials in this area.

Trial registration

This study was prospectively registered April 2012 with Clinical Trials.gov (#NCT01766141).

https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0003ZIL&selectaction=Edit&uid=U0001V74&ts=2&cx=-axvqtg

Cohort profile: why do people keep hurting their back?

OBJECTIVE

Low back pain (LBP) is one of the most disabling and costly conditions worldwide. It remains unclear why many individuals experience persistent and recurrent symptoms after an acute episode whereas others do not. A longitudinal cohort study was established to address this problem. We aimed to; (1) evaluate whether promising and potentially modifiable biological, psychological, social and behavioural factors, along with their possible interactions, predict LBP outcome after an acute episode; (2) compare these factors between individuals with and without acute LBP; and (3) evaluate the time-course of changes in these factors from LBP onset. This paper outlines the methodology and compares baseline characteristics between acute LBP and control, and LBP participants with and without follow-up.

RESULTS

133 individuals with acute LBP and 74 pain-free individuals participated. Bio-psycho-social and behavioural measures were collected at baseline and 3-monthly for 12 months (LBP) or 3 months (control). Pain and disability were recorded fortnightly. Baseline characteristics were mostly similar between those who did and did not return for follow-up. Initial analyses of this cohort have revealed important insights into the pathways involved in acute-to-chronic LBP. These and future findings will provide new targets for treatment and prevention of persistent and recurrent LBP.

AAAPT Diagnostic Criteria for Acute Low Back Pain with and Without Lower Extremity Pain

OBJECTIVE

Low back pain is one of the most common reasons for which people visit their doctor. Between 12% and 15% of the US population seek care for spine pain each year, with associated costs exceeding $200 billion. Up to 80% of adults will experience acute low back pain at some point in their lives. This staggering prevalence supports the need for increased research to support tailored clinical care of low back pain. This work proposes a multidimensional conceptual taxonomy.

METHODS

A multidisciplinary task force of the ACTTION-APS-AAPM Pain Taxonomy (AAAPT) with clinical and research expertise performed a focused review and analysis, applying the AAAPT five-dimensional framework to acute low back pain.

RESULTS

Application of the AAAPT framework yielded the following: 1) Core Criteria: location, timing, and severity of acute low back pain were defined; 2) Common Features: character and expected trajectories were established in relevant subgroups, and common pain assessment tools were identified; 3) Modulating Factors: biological, psychological, and social factors that modulate interindividual variability were delineated; 4) Impact/Functional Consequences: domains of impact were outlined and defined; 5) Neurobiological Mechanisms: putative mechanisms were specified including nerve injury, inflammation, peripheral and central sensitization, and affective and social processing of acute low back pain.

CONCLUSIONS

The goal of applying the AAAPT taxonomy to acute low back pain is to improve its assessment through a defined evidence and consensus-driven structure. The criteria proposed will enable more rigorous meta-analyses and promote more generalizable studies of interindividual variation in acute low back pain and its potential underlying mechanisms.

Systemic inflammatory markers in neck pain: A systematic review with meta-analysis

BACKGROUND AND OBJECTIVE

Mechanisms underpinning symptoms in non-traumatic neck pain (NTNP) and whiplash-associated disorder (WAD) are not comprehensively understood. There is emerging evidence of systemic inflammation in musculoskeletal pain conditions, including neck and back pain. The aim of this systematic review was to determine if raised blood inflammatory markers are associated with neck pain.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, Cochrane Library, CINAHL and Web of Science databases were searched. Two independent reviewers identified studies for inclusion and extracted data. Meta-analysis was performed by random effects model to calculate standard mean differences (SMDs). Risk of bias of individual studies was assessed using the Newcastle-Ottawa Scale. Overall quality of evidence from meta-analysis was assessed by Grades of Recommendation, Assessment, Development and Evaluation approach.

RESULTS

In total, 10 studies were included comprising 706 participants. Three studies provided data for acute WAD, two for chronic WAD, four for chronic NTNP and one for chronic mixed WAD and NTNP. Meta-analysis indicated increased interleukin 1β (SMD: 0.84 [95% CI 0.24, 1.44], p = .01, I2  = 59%) and tumour necrosis factor α (SMD: 0.59 [0.09, 1.09], p = .02, I2  = 45%) in chronic neck pain compared to controls, but no increase in monocyte chemoattractant protein-1. Some inflammatory markers were associated with clinical variables (including pain intensity and disability). Quality of evidence was mostly low due to small samples and high heterogeneity.

CONCLUSIONS

Findings imply that raised blood inflammatory markers are present in chronic neck pain, which may represent an ongoing inflammatory process in this population.

SIGNIFICANCE

This systematic review advances our understanding of neck pain pathophysiology by demonstrating the presence of systemic inflammation in chronic neck pain, in the form of raised IL-1β and TNFα. Further, numerous inflammatory markers were associated with clinical variables, including pain intensity, disability and hyperalgesia. These findings imply that systemic inflammation may contribute to mechanisms underlying neck pain.

Clinical features as predictors of histologically confirmed inflammation in patients with lumbar disc herniation with associated radiculopathy

Background

An understanding of the clinical features of inflammation in low back pain with or without leg symptoms may allow targeted evaluations of anti-inflammatory treatment in randomised-controlled-trials and clinical practice.

Purpose

This study evaluated the diagnostic accuracy of clinical features to predict the presence/absence of histologically confirmed inflammation in herniated disc specimens removed at surgery in patients with lumbar disc herniation and associated radiculopathy (DHR).

Study design

Cohort Study.

Methods

Disc material from patients with DHR undergoing lumbar discectomy was sampled and underwent histological/immunohistochemistry analyses. Control discs were sampled from patients undergoing surgical correction for scoliosis. Baseline assessment comprising sociodemographic factors, subjective examination, physical examination and psychosocial screening was conducted and a range of potential clinical predictors of inflammation developed based on the existing literature. Multi-variate analysis was undertaken to determine diagnostic accuracy.

Results

Forty patients with DHR and three control patients were recruited. None of the control discs had evidence of inflammation compared to 28% of patients with DHR. Predictors of the presence of histologically confirmed inflammation included back pain < 5/10, symptoms worse the next day after injury, lumbar flexion range between 0 and 30° and a positive clinical inflammation score (at least 3 of: constant symptoms, morning pain/stiffness greater than 60-min, short walking not easing symptoms and significant night symptoms). The model achieved a sensitivity of 90.9%, a specificity of 92.9%, and a predictive accuracy of 92.3%.

Conclusion

In a sample of patients with lumbar DHR a combination of clinical features predicted the presence or absence of histologically confirmed inflammation.

Clinical relevance

These clinical features may enable targeted anti-inflammatory treatment in future RCTs and in clinical practice.

The Pelvic Girdle Pain deadlock: 2. Topics that, so far, have remained out of focus

INTRODUCTION

In our preceding paper, we concluded that Pelvic Girdle Pain (PGP) should be taken seriously. Still, we do not know its causes. Literature reviews on treatment fail to reveal a consistent pattern, and there are patients who do not respond well to treatment. We designated the lack of progress in research and in the clinic as 'deadlock', and proposed a 'deconstruction' of PGP, that is to say, taking PGP apart into its relevant dimensions.

PURPOSE

We examine the proposition that PGP may emerge as local inflammation. Inflammation would be a new dimension to be taken into account, between biomechanics and psychology. To explore the consequences of this idea, we present four different topics that, so far, have remained out of focus. One: The importance of microtrauma. Two: Ways to counteract chronification. Three: The importance of sickness behaviour when systemic inflammation turns into neuroinflammation of the brain. And Four: The mainly emotional and cognitive nature of chronic pain, and how aberrant neuroinflammation may render chronic pain intractable. For intractable pain, sleep and stress management are promising treatment options.

IMPLICATIONS

The authors hope that the present paper helps to stimulate the flexible creativity that is required to deal with the biological and psychological impact of PGP. Measuring inflammatory mediators in PGP should be a research priority. It should be understood that the boundaries between biology and psychology are becoming blurred. Clinicians must frequently monitor pain, disability, and mood, and be ready to switch treatment whenever the patient does not improve.

Modulation of the In Vivo Inflammatory Response by Pro- Versus Anti-Inflammatory Intervertebral Disc Treatments

Inflammation is central in intervertebral disc (IVD) degeneration/regeneration mechanisms, and its balance is crucial to maintain tissue homeostasis. This work investigates the modulation of local and systemic inflammatory response associated with IVD degeneration/herniation by administration of PRO- versus ANTI-inflammatory treatments. Chitosan/poly-γ-glutamic acid nanocomplexes, known as pro-inflammatory (PRO), and soluble diclofenac, a non-steroidal anti-inflammatory drug (ANTI), were intradiscally administered in a rat IVD injury model, 24 h after lesion. Two weeks after administration, a reduction of disc height accompanied by hernia formation was observed. In the PRO-inflammatory treated group, IL-1β, IL-6 and COX-2 IVD gene expression were upregulated, and loss of nucleus pulposus (NP) structure and composition was observed. Systemically, lower T-cell frequency was observed in the lymph nodes (LN) and spleen (SP) of the PRO group, together with an increase in CD4+ T cells subset in the blood (BL) and LN. In contrast, the ANTI-group had higher proteoglycans/collagen ratio and collagen type 2 content in the NP, while an increase in the frequency of myeloid cells, M1 macrophages and activated macrophages (MHCII+) was observed at the systemic level. Overall, this study illustrates the dynamics of local and systemic inflammatory and immune cell responses associated with intradiscal therapies, which will contribute to designing more successful immunomodulatory treatments for IVD degeneration.

A systematic review of the role of inflammatory biomarkers in acute, subacute and chronic non-specific low back pain

Background

Low back pain (LBP) is one of the greatest contributors to disability in the world and there is growing interest on the role of biomarkers in LBP. To purpose of this review was to analyze available evidence on the relationship between inflammatory biomarkers, clinical presentation, and outcomes in patients with acute, subacute and chronic non-specific low back pain (NSLBP).

Methods

A search was performed in Medline, Embase, Cinahl and Amed databases. Studies which measured levels of inflammatory biomarkers in participants with NSLBP were included. Two reviewers independently screened titles and abstracts, full-texts, and extracted data from included studies. Methodological quality was assessed using the Newcastle Ottawa Quality Assessment Scale. Level of evidence was assessed using the modified GRADE approach for prognostic studies.

Results

Seven primary studies were included in this review. All results assessed using the modified GRADE demonstrated low to very low quality evidence given the small number of studies and small sample. Three studies examined C-reactive protein (CRP), one of which found significantly higher CRP levels in an acute NSLBP group than in controls and an association between high pain intensity and elevated CRP. Three studies examined tumor necrosis factor alpha (TNF-α), two of which found elevated TNF-α in chronic NSLBP participants compared to controls. Two studies examined interleukin 6 (IL-6), none of which found a significant difference in IL-6 levels between NSLBP groups and controls. Two studies examined interleukin 1 beta (IL-β), none of which found a significant difference in IL-β levels between NSLBP groups and controls.

Conclusions

This review found evidence of elevated CRP in individuals with acute NSLBP and elevated TNF-Α in individuals with chronic NSLBP. There are a limited number of high-quality studies evaluating similar patient groups and similar biomarkers, which limits the conclusion of this review.