Relative contributions of the nervous system, spinal tissue and psychosocial health to non-specific low back pain: Multivariate meta-analysis

[Avoidance-endurance fast screen : AEFS validation with one- and two-level response scaling in healthy subjects]

BACKGROUND AND OBJECTIVES

Chronic pain affects an enormous number of patients in Germany. Therefore, early detection is important using easy, quick and reasonable screening methods. The avoidance-endurance fast screen is currently available in two different versions: one asking for pain-related behaviour in light and severe pain and the other assessing overall severe pain-related behaviour. In this study we aim to examine the agreement between both scales and for the first time describe the role of protective psychological features such as resilience and self-compassion in this model.

MATERIALS AND METHODS

Epidemiological cross-sectional study (n = 278) of a healthy cohort occasionally experiencing pain (< 3 months). The analysis was done using standard descriptive statistics, correlations (Spearman's rho) and deductive statistics (t-tests and one-factor ANOVA with post hoc Bonferroni correction) and effect sizes (Cohen's d). Matching of the instruments was calculated with Cohen's kappa.

RESULTS

The results showed a moderate agreement for the two versions. A validity check of the subgroups resulted in comparable findings. The one-level version scored higher in terms of pain persistence which caused subgroup changes from adaptive to eustress-endurance responses and from fear-avoidance to distress-endurance responses. The distress-endurance subgroup had significantly lower values of the trait self-compassion.

CONCLUSIONS

Based on the results of this study, the quality of agreement between the two AEFS versions is considered strong. Without the comparison between mild and strong pain, endurance behaviour was reported more often. According to these findings, overestimation of pain persistence behaviour using the one-level version might result. Therefore, future studies should re-evaluate the cut-offs. As reported in previous studies, protective psychological features showed the highest scores in the eustress-endurance subgroup.

The Influence of Pain Hypersensitivity and Psychological Factors on Pain and Disability in the Transition From Acute to Chronic Low Back Pain: A Longitudinal Exploratory Investigation and Cluster Analysis

Pain hypersensitivity is present in some people with acute low back pain (LBP) and thought to be involved in the development of chronic LBP. Early evidence suggests that pain hypersensitivity in acute LBP precedes poor long-term outcome. We aimed to examine whether the presence of pain hypersensitivity in acute LBP influenced recovery status at 6 months and differentiated how pain and disability changed over time. Participants with acute nonspecific LBP (<6 weeks after pain onset, N = 118) were included in this longitudinal study. Quantitative sensory testing, including pressure and heat pain thresholds, and conditioned pain modulation and questionnaires were compared at baseline and longitudinally (at 3 and 6 months) between recovered and unrecovered participants. Using k-means clustering, we identified subgroups based on baseline sensory measures alone, and in combination with psychological factors, and compared pain and disability outcomes between subgroups. Sensory measures did not differ at baseline or longitudinally between recovered (N = 50) and unrecovered (N = 68) participants. Subgrouping based on baseline sensory measures alone did not differentiate pain or disability outcomes at any timepoint. Participants with high psychological distress at baseline (N = 19) had greater disability, but not pain, at all timepoints than those with low psychological distress, regardless of the degrees of pain sensitivity. Our findings suggest that pain hypersensitivity in acute LBP does not precede poor recovery at 6 months or differentiate how pain and disability change over time. High psychological distress during acute LBP is associated with unremitting and pronounced disability, while pain severity is unaffected. PERSPECTIVE: Pain hypersensitivity is thought to be involved in the transition to chronic LBP. Contradictory to prevailing hypothesis, our findings suggest pain hypersensitivity alone in acute LBP does not precede poor recovery. High psychological distress in acute LBP has a stronger influence than pain hypersensitivity on long-term disability, but not pain outcomes.

How to Interpret Effect Sizes for Biopsychosocial Outcomes and Implications for Current Research

Biopsychosocial factors are associated with pain, but they can be difficult to compare. One way of comparing them is to use standardized mean differences. Previously, these effects sizes have been termed as small, medium, or large, if they are bigger than or equal to, respectively, .2, .5, or .8. These cut-offs are arbitrary and recent evidence showed that they need to be reconsidered. We argue it is necessary to determine cut-offs for each biopsychosocial factor. To achieve this, we propose 3 potential approaches: 1) examining, for each factor, how the effect size differs depending upon disease severity; 2) using an existing minimum clinically important difference to anchor the large effect size; and 3) define cut-offs by comparing data from people with and without pain. This is important for pain research, as exploring these methodologies has potential to improve comparability of biopsychosocial factors and lead to more directed treatments. We note assumptions and limitations of these methods that should also be considered. PERSPECTIVE: Standardized mean differences can estimate effect sizes between groups and could theoretically allow for comparison of biopsychosocial factors. However, common thresholds to define effect sizes are arbitrary and likely differ based on outcome. We propose methods that could overcome this and be used to derive biopsychosocial outcome-specific effect sizes.

[Physiotherapeutic differential diagnosis of back pain associated with endometriosis]

BACKGROUND

Endometriosis (EM) is one of the most common gynecologic conditions in our society. The diagnosis takes an average of 7 to 10 years. To shorten this period, this syndrome needs more attention. The aim of this article is to show overlaps between EM and low back pain (LBP) and to describe their relevance for physiotherapeutic screening.

OBJECTIVES

What clinical signs do the syndromes EM and LBP have in common and to what extent can physiotherapeutic screening take gynecological aspects into account and be adapted accordingly?

RESULTS

To answer this question, the two syndromes were screened for overlaps. These overlaps were then related to the existing literature and case studies. The current research situation shows overlaps of the two syndromes with regard to the etiology, the pain mechanism as well as a psychosocial aspect. The literature shows that more women than men are affected by LBP and other chronic pain syndromes. EM occurs almost exclusively in women and, like LBP, is considered a chronic pain syndrome. Thus, a common pain mechanism of the two syndromes is discussed in the literature. The most frequent overlap of the two syndromes is shown by the occurrence of LBP as a frequent symptom of EM. This connection can be justified by structural causes as well as by a reflex pain presentation.

CONCLUSION

In a physiotherapeutic setting, evidence of EM can be observed in the history and physical examination. Considering these factors may help shorten the diagnosis time of endometriosis by referring for further evaluation if gynecologic involvement is suspected in LBP. A comprehensive history is important and should cover urologic, gynecologic, as well as sexual history. In this article, the term woman is used to refer to the biological female sex and is not related to individual gender identity. The clinical picture mainly affects women, which is why in the following work, as far as it concerns the people suffering from the disease, it is not used in the opposite sense.

Personalized assessment and management of non-specific low back pain

BACKGROUND AND OBJECTIVE

Low back pain (LBP), and in particular non-specific low back pain (NSLBP), which accounts for approximately 90% of LBP, is the leading cause of years lived with disability worldwide. In clinical trials, LBP is often poorly categorized into 'specific' versus 'non-specific' and 'acute' versus 'chronic' pain. However, a better understanding of the underlying pain mechanisms might improve study results and reduce the number of NSLBP patients.

DATABASES AND DATA TREATMENT

Narrative review.

RESULTS

NSLBP is a multi-dimensional, biopsychosocial condition that requires all contributing dimensions to be assessed and prioritized. Thereby, the assessment of the contribution of nociceptive, neuropathic and nociplastic pain mechanisms forms the basis for personalized management. In addition, psychosocial (e.g. anxiety, catastrophizing) and contextual factors (e.g. work situation) as well as comorbidities need to be assessed and individually weighted. Personalized treatment of NSLBP further requires individually choosing treatment modalities, for example, exercising, patient education, cognitive-behavioural advice, pharmacotherapy, as well as tailoring treatment within these modalities, for example, the delivery of tailored psychological interventions or exercise programs. As the main pain mechanism and psychosocial factors may vary over time, re-assessment is necessary and treatment success should ideally be assessed quantitatively and qualitatively.

CONCLUSIONS

The identification of the main contributing pain mechanism and the integration of the patients' view on their condition, including beliefs, preferences, concerns and expectations, are key in the personalized clinical management of NSLBP. In research, particular importance should be placed on accurate characterization of patients and on including outcomes relevant to the individual patient.

SIGNIFICANCE STATEMENT

Here, a comprehensive review of the challenges associated with the diagnostic label 'non-specific low back pain' is given. It outlines what is lacking in current treatment guidelines and it is summarized what is currently known with respect to individual phenotyping. It becomes clear that more research on clinically meaningful subgroups is needed to best tailor treatment approaches.

Influence of radiological factors, psychosocial factors, and central sensitization-related symptoms on clinical symptoms in patients with lumbar spinal canal stenosis

BACKGROUND

No study to date has concurrently evaluated the impact of radiological factors, psychosocial factors, and central sensitization (CS) related symptoms in a single lumbar spinal canal stenosis (LSS) patient cohort.

OBJECTIVE

To investigate the associations between these factors and clinical symptoms in LSS patients.

METHODS

We recruited 154 patients with LSS scheduled for surgery. Patient-reported outcome measures and imaging evaluation including clinical symptoms, psychosocial factors, CS-related symptoms, and radiological classifications. Spearman's rank correlation coefficient and multiple regression analyses were employed.

RESULTS

Spearman's correlation revealed CS-related symptoms positively correlated with low back pain (r= 0.25, p< 0.01), leg pain (r= 0.26, p< 0.01), and disability (r= 0.32, p< 0.01). Pain catastrophizing positively correlated with leg pain (r= 0.23, p< 0.01) and disability (r= 0.36, p< 0.01). Regression analysis showed that pain catastrophizing was associated with disability (β= 0.24, 95%CI = 0.03-0.18), and CS-related symptoms with low back pain (β= 0.28, 95%CI = 0.01-0.09). Radiological classifications were not associated with clinical symptoms.

CONCLUSION

Our findings suggest that psychosocial factors and CS-related symptoms, rather than radiological factors, seem to contribute to clinical symptoms in patients with LSS.

A model for personalized diagnostics for non-specific low back pain: the role of the myofascial unit

Low back pain (LBP) is the leading cause of disability worldwide. Most LBP is non-specific or idiopathic, which is defined as symptoms of unknown origin without a clear specific cause or pathology. Current guidelines for clinical evaluation are based on ruling out underlying serious medical conditions, but not on addressing underlying potential contributors to pain. Although efforts have been made to identify subgroups within this population based on response to treatment, a comprehensive framework to guide assessment is still lacking. In this paper, we propose a model for a personalized mechanism-based assessment based on the available evidence that seeks to identify the underlying pathologies that may initiate and perpetuate central sensitization associated with chronic non-specific low back pain (nsLBP). We propose that central sensitization can have downstream effects on the "myofascial unit", defined as an integrated anatomical and functional structure that includes muscle fibers, fascia (including endomysium, perimysium and epimysium) and its associated innervations (free nerve endings, muscle spindles), lymphatics, and blood vessels. The tissue-level abnormalities can be perpetuated through a vicious cycle of neurogenic inflammation, impaired fascial gliding, and interstitial inflammatory stasis that manifest as the clinical findings for nsLBP. We postulate that our proposed model offers biological plausibility for the complex spectrum of clinical findings, including tissue-level abnormalities, biomechanical dysfunction and postural asymmetry, ecological and psychosocial factors, associated with nsLBP. The model suggests a multi-domain evaluation that is personalized, feasible and helps rule out specific causes for back pain guiding clinically relevant management. It may also provide a roadmap for future research to elucidate mechanisms underlying this ubiquitous and complex problem.

Towards data-driven biopsychosocial classification of non-specific chronic low back pain: a pilot study

The classification of non-specific chronic low back pain (CLBP) according to multidimensional data could guide clinical management; yet recent systematic reviews show this has not been attempted. This was a prospective cross-sectional study of participants with CLBP (n = 21) and age-, sex- and height-matched pain-free controls (n = 21). Nervous system, lumbar spinal tissue and psychosocial factors were collected. Dimensionality reduction was followed by fuzzy c-means clustering to determine sub-groups. Machine learning models (Support Vector Machine, k-Nearest Neighbour, Naïve Bayes and Random Forest) were used to determine the accuracy of classification to sub-groups. The primary analysis showed that four factors (cognitive function, depressive symptoms, general self-efficacy and anxiety symptoms) and two clusters (normal versus impaired psychosocial profiles) optimally classified participants. The error rates in classification models ranged from 4.2 to 14.2% when only CLBP patients were considered and increased to 24.2 to 37.5% when pain-free controls were added. This data-driven pilot study classified participants with CLBP into sub-groups, primarily based on psychosocial factors. This contributes to the literature as it was the first study to evaluate data-driven machine learning CLBP classification based on nervous system, lumbar spinal tissue and psychosocial factors. Future studies with larger sample sizes should validate these findings.

Classifying Nonspecific Low Back Pain for Better Clinical Outcomes: Current Challenges and Paths Forward

SYNOPSIS: Low back pain classification systems are structured assessments used to guide choices of more specific treatments. Classification systems examined in randomized controlled trials have limited effects on pain intensity and disability compared to nonclassified interventions. Potential reasons for the lack of efficacy include (1) failing to assess multidimensional factors that contribute to pain, (2) relying on clinician judgement, (3) low accessibility, and (4) poor classification reliability. Overcoming these limitations is critical to deciding whether classification systems can improve clinical practice. Only once these limitations are addressed, can we feel certain about the efficacy, or lack thereof, of classification systems. This Viewpoint guides the reader through some limitations of common classification approaches and presents a path forward to open-access, reliable, and multidimensional precision medicine for managing low back pain. J Orthop Sports Phys Ther 2023;53(5):1-5. Epub: 5 April 2023. doi:10.2519/jospt.2023.11658.

Isokinetic trunk training on pain, disability, and strength in non-specific low back pain patients: A systematic review and meta-analysis

BACKGROUND

Low back pain is one of the leading causes of disability globally, with a high economic and social burden. A decrease or imbalance in trunk strength has been associated with the occurrence of low back pain and its severity. Trunk strength training is helpful in the treatment of Non-specific low back pain (NSLBP) patients. However, we do not know the effects of trunk isokinetic training (IKT) on pain intensity, disability, and trunk strength.

OBJECTIVE

This systematic review aimed to determine the effects of trunk IKT in NSLBP patients on pain intensity, disability, and trunk flexor and extensor isokinetic strength.

METHODS

We searched PubMed, Web of Science, Scopus, CENTRAL, and PEDro, from January 2001 until March 2021 and updated to November 2022. Randomized controlled trials (RCTs) that investigated the effect of IKT in adult participants with NSLBP on pain intensity, disability, or isokinetic trunk strength were included. Mean difference (MD) and 95% confidence intervals (95% CI) were calculated for pain. Bias was assessed using the Cochrane risk of bias (RoB) tool and evidence certainty via Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Among 1750 retrieved articles, eight were included in this review. Meta-analysis comparing IKT (trunk isokinetic training, n= 134) with control groups (conventional exercises, n= 133) revealed that IKT decreases pain intensity (MD -1.50 (95% CI: -2.60; -0.39)) immediately post-intervention, and one month (MD -1.97 (95% CI: -2.92; -1.03)) and at six months follow-up (MD -2.48 (95% CI: -2.77; -2.19)), although with a very low to low quality according to the GRADE rating. Besides, IKT decreases disability and increases isokinetic trunk strength, but with scant evidence.

CONCLUSIONS

Trunk IKT could be a novel clinical tool for pain management in patients with NSLBP, although evidence is scarce. In addition, few RCTs exist for IKT on disability or trunk isokinetic strength in patients with NSLBP. Therefore, further research on this topic is needed.

Assessing Psychological Flexibility and Inflexibility in Chronic Pain Using the Multidimensional Psychological Flexibility Inventory (MPFI)

Psychological flexibility (PF) is a model of well-being and daily functioning that is applied to chronic pain, and is the model behind Acceptance and Commitment Therapy (ACT). However, studies of PF in chronic pain are limited by the lack of a single measure capturing all facets. The Multidimensional Psychological Flexibility Inventory (MPFI) assesses all facets of PF and psychological inflexibility (PI) and could remedy this problem. The current study employs this measure. Adult participants with chronic pain (N = 404) were recruited online and completed the MPFI, other validated measures of PF/PI, and measures of pain, work and social adjustment, and depression, at two time points. The reliability, factor structure, and validity of the MPFI were assessed. Confirmatory factor analysis results demonstrated a good model fit for the proposed factor-and subscale structure. Correlations between MPFI and theoretically similar measures were moderate to strong, and correlations with pain intensity, pain interference, work-and social adjustment, and depression, were small to large. In this first examination of the potential utility of the MPFI within a chronic pain population, we found it to be valid and reliable. It should be noted that the MPFI was less predictive of outcomes compared with more established measures in most cases. Despite this, results from the wide range of variables available from the MPFI highlights the potential importance of aspects of PF and PI not previously emphasized, including the greater predictive utility of the inflexibility facets. Further use and study of the MPFI is recommended. ClinicalTrials.gov ID: NCT05050565 PERSPECTIVE: This article presents a comprehensive examination of a self-report measure assessing all facets of psychological flexibility and inflexibility, in a chronic pain sample. The results support the role of facets not previously emphasized. Comprehensive assessment of PF and PI appears possible and is recommended depending on research questions being asked.

The power of integrating data: advancing pain research using meta-analysis

Publications related to pain research have increased significantly in recent years. The abundance of new evidence creates challenges staying up to date with the latest information. A comprehensive understanding of the literature is important for both clinicians and investigators involved in pain research. One commonly used method to combine and analyse data in health care research is meta-analysis. The primary aim of a meta-analysis is to quantitatively synthesise the results of multiple studies focused on the same research question. Meta-analysis is a powerful tool that can be used to advance pain research. However, there are inherent challenges when combining data from multiple sources. There are also numerous models and statistical considerations when undertaking a meta-analysis. This review aims to discuss the planning and preparation for completing a meta-analysis, review commonly used meta-analysis models, and evaluate the clinical implications of meta-analysis in pain research.

Chronic back pain sub-grouped via psychosocial, brain and physical factors using machine learning

Chronic back pain (CBP) is heterogenous and identifying sub-groups could improve clinical decision making. Machine learning can build upon prior sub-grouping approaches by using a data-driven approach to overcome clinician subjectivity, however, only binary classification of pain versus no-pain has been attempted to date. In our cross-sectional study, age- and sex-matched participants with CBP (n = 4156) and pain-free controls (n = 14,927) from the UkBioBank were included. We included variables of body mass index, depression, loneliness/social isolation, grip strength, brain grey matter volumes and functional connectivity. We used fuzzy c-means clustering to derive CBP sub-groups and Support Vector Machine (SVM), Naïve Bayes, k-Nearest Neighbour (kNN) and Random Forest classifiers to determine classification accuracy. We showed that two variables (loneliness/social isolation and depression) and five clusters were optimal for creating sub-groups of CBP individuals. Classification accuracy was greater than 95% for when CBP sub-groups were assessed only, while misclassification in CBP sub-groups increased to 35-53% across classifiers when pain-free controls were added. We showed that individuals with CBP could sub-grouped and accurately classified. Future research should optimise variables by including specific spinal, psychosocial and nervous system measures associated with CBP to create more robust sub-groups that are discernible from pain-free controls.

What influences graduate medical students' beliefs of lower back pain? A mixed methods cross sectional study

BACKGROUND

Low back pain (LBP) is a common condition with substantial associated disability and costs, best understood using a biopsychosocial approach. Research demonstrates that beliefs about LBP are important, with biomedical beliefs influencing practitioner's management and patient recovery. Beliefs about LBP can be inconsistent amongst healthcare and medical students. The aim of this study was to investigate graduate medical student's beliefs of LBP and what influences them.

METHOD

A cross sectional mixed methods study of Phase 1 (first year) and Phase 3 (third and fourth year) current graduate medical students at the University of Warwick (MBChB) was conducted. Participants were recruited via voluntary response sampling. A survey investigated LBP beliefs, utilising the Back Beliefs Questionnaire (BBQ) and Health Care Providers' Pain and Impairment Relationship Scale (HC-PAIRS). Qualitative data was collected on what influences beliefs about the causes and management of LBP, which was analysed descriptively using thematic analysis.

RESULTS

Fifty-seven students completed the questionnaire (61% female), with a mean age of 27.2 years. Eighty two percent of participants reported a history of LBP. Median BBQ scores were 31.5 for phase 1 and 31 for phase 3, with median HC-PAIRS scores of 57 and 60 for phase 1 and phase 3 students respectively. Three main themes emerged from the qualitative data: Sources of influence, influence of personal experience and influence of medical education. Participants discussed single or multiple sources influencing their beliefs about the causes and management of LBP. Another main theme was the influence of experiencing LBP personally or through discussions with family, friends and patients. The final main theme described the influence of medical education, including lectures, seminars and clinical placements.

CONCLUSIONS

The HC-PAIRS and BBQ scores suggest graduate medical students in this sample tended to have positive beliefs about the outcome of LBP and functional expectations of chronic LBP patients, consistent with other healthcare students. The findings from qualitative data suggest how medical students form beliefs about the causes and management of LBP is complex.