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

Comparative effectiveness of various exercise interventions on central sensitisation indices: A systematic review and network meta-analysis

BACKGROUND

Central sensitisation (CS) increases musculoskeletal pain. Quantitative sensory testing (QST) or self-report questionnaires might indicate CS. Indices of CS might be suppressed by exercise, although the optimal exercise regimen remains unclear.

OBJECTIVES

We conducted a systematic review and network meta-analysis (NMA) to investigate effectiveness of different exercise regimens on these CS indices in adults.

METHODS

We searched 6 electronic databases from inception to November 2023. Meta-analysis of randomised controlled trials (RCTs) investigated effects of exercise on all CS indices. Two independent reviewers assessed risk of bias. NMA of RCTs compared CS indices between exercise types. Sensitivity analysis using only high-quality studies was performed to verify the robustness of our results. Certainty was assessed using the GRADE approach.

RESULTS

Of the 249 eligible studies identified, 164 were RCTs, of which 89 provided data suitable for NMA. Meta-analysis revealed large improvement of post-intervention CS indices compared to baseline (SMD -0.81, 95 % CI -0.93 to -0.70). All reported categories of exercise, except stretching exercise alone, were more effective than non-exercise controls. Combined exercises that include stretching together with strengthening exercises (SMD -1.67, 95 % Credible Interval (CrI) -2.41 to -0.97), or strengthening, stretching and aerobic components (SMD -1.61, 95 % CrI -2.74 to -0.56) were most effective at reducing CS indices compared to non-exercise controls. Sensitivity analysis confirmed the robustness of our findings, particularly for combined stretching and strengthening exercise.

CONCLUSIONS

Our meta-analysis suggested that various exercise interventions are effective in improving CS. Multi-component exercise tends to be the most effective, but some exercise combinations might be better than others. Combined exercise featuring strengthening and stretching components, with or without aerobic exercise, shows the greatest likelihood among other combinations of being the optimal exercise type. These findings might have utility informing future trials and personalising treatment strategies for people with CS features.

Subgroup characteristics in care workers with low back pain: cluster analysis-based severity of central sensitivity syndromes and low back pain

PURPOSE

This multicentre, collaborative, cross-sectional study aimed to explore the characteristics of subgroups based on central sensitivity syndromes (CSSs) and low back pain (LBP) severity. Furthermore, we investigated the relationship between the classified subgroups and work status among the care workers.

PATIENTS AND METHODS

In 660 care workers, we assessed LBP intensity, pain duration, pain sites, CSS (using the central sensitization inventory-9), psychological factors (using the pain catastrophizing scale and pain self-efficacy questionnaire), and work status (interference, amount of assistance, frequency of assistance, and work environment). We used hierarchical clustering analysis to divide the participants into subgroups based on CSS and LBP severity. We further performed multiple comparison analyzes and adjusted the residuals (chi-square test) to reveal differences between clusters.

RESULTS

Care workers with LBP were divided into four subgroups (Cluster 1: no CSS and mild LBP, Cluster 2: mild CSS and severe LBP, Cluster 3: mild CSS and mild LBP, Cluster 4: severe CSS and moderate LBP). Cluster 4 tended to have a higher number of pain sites, severe pain catastrophizing, and poor pain self-efficacy. In addition, Cluster 4 showed a higher frequency of assistance and an inadequate working environment and equipment. By contrast, Cluster 2 tended to have low pain self-efficacy. In addition, Cluster 2 experienced the highest work-related interference compared with any of the subgroups.

CONCLUSION

Our findings suggested that the severe LBP and severe CSS subgroups had common and different characteristics concerning psychological factors and work status, including interference with work. Our results may help to improve the management of care workers with LBP.

Characterizing clinical progression in patients with musculoskeletal pain by pain severity and central sensitization-related symptoms

Central sensitization-related symptoms (CSS) are associated with the severity and progression of pain. The relationship between the severity of pain/CSS and clinical progresses remains unclear. This multicenter, collaborative, longitudinal study aimed to characterize the clinical outcomes of patients with musculoskeletal pain by classifying subgroups based on the severity of pain/CSS and examining changes in subgroups over time. We measured the pain intensity, CSS, catastrophic thinking, and body perception disturbance in 435 patients with musculoskeletal pain. Reevaluation of patients after one month included 166 patients for pain intensity outcome and 110 for both pain intensity and CSS outcome analysis. We classified the patients into four groups (mild pain/CSS, severe pain/mild CSS, severe pain/CSS, and mild pain/severe CSS groups) and performed multiple comparison analyses to reveal the differences between the CSS severity groups. Additionally, we performed the adjusted residual chi-square to identify the number of patients with pain improvement, group transition, changing pain, and CSS pattern groups at baseline. The most characteristic result was that the mild and severe CSS groups showed worsening pain. Moreover, many of the group transitions were to the same group, with a few transitioning to a group with mild pain/CSS. Our findings suggest that the severity and improvement of CSS influence pain prognosis.

Occupational low back pain among Japanese caregivers: A large-scale cross-sectional study

BACKGROUND

Caregivers in Japan experience a high prevalence of low back pain (LBP), with age, sex, individual pain experiences, and central sensitization symptoms potentially influencing its chronic progression.

OBJECTIVE

To determine the prevalence of LBP among caregivers, as well as its relation to age and sex, and explore work status, psychological factors, and central sensitization symptoms as contributing factors to chronic LBP (CLBP).

METHODS

A large-scale cross-sectional survey was conducted among 1214 caregivers in 35 geriatric healthcare facilities. The survey assessed LBP and CLBP prevalence, work status, psychological factors, and central sensitization-related symptoms. Multivariate logistic regression analysis was used to identify factors influencing CLBP.

RESULTS

Among 936 valid respondents, the LBP prevalence was 69.2%. No significant sex differences were found in the prevalence of LBP and CLBP. Old age, higher pain severity, and severe symptoms related to central sensitization increased the risk of CLBP. However, work status and psychological factors did not significantly contribute to CLBP.

CONCLUSION

There is a high prevalence of LBP among caregivers, age and individual pain experience significantly impact CLBP. These findings emphasize the need for therapeutic strategies to manage pain intensity, especially in the acute phase, to prevent the progression to chronicity.

Investigation for Factors Affecting Body Perception Disturbance in Patients with Low Back Pain by Mechanism-Based Classification of Pain: A Cross-Sectional Study

Background

Central sensitization is a pathophysiological cause of chronic low back pain and is linked with psychosocial factors. The association between central sensitization (CS) and body perception disturbance is currently unclear, and no prior studies have investigated this relationship in patients with acute or subacute low back pain. The objective of this study was to investigate potential factors that influence body perception disturbance using a mechanistic classification of low back pain.

Methods

This cross-sectional study was conducted at the time of initial physical therapy in patients with low back pain. During the study period, 169 patients were recruited. Pain intensity, disease duration, disability, CS, and body perception disturbance were evaluated. Patients were divided into three groups according to the pathology of low back pain, and multivariate analysis was used to examine factors affecting body perception disturbance. The dependent variable was Fremantle Back Awareness Questionnaire (FreBAQ); the independent variables were age, gender, BMI, VAS, disease duration, RDQ, and CS Inventory-9 (CSI-9).

Results

A total of 117 patients were included in our analysis. According to the mechanistic classification of pain, 66 (56.4%), 36 (30.8%), and 15 (12.8%) patients were categorized as having nociceptive pain (NP), peripheral neuropathic pain (PNP), and CS pain (CSP), respectively. Patients with PNP or CSP were significantly older than those with NP (p  <  0.01). FreBAQ and RDQ scores were significantly higher in patients with CSP than those with NP (p  <  0.05). The results of multiple regression analyses indicated that CSI-9 scores were significantly associated with FreBAQ (p  <  0.01).

Conclusion

Patients with CS syndrome and low back pain tend to have higher CSI-9 scores and be older. Body perception disturbance is influenced by CS or CS syndrome, regardless of the stage of low back pain, suggesting that patients with chronic low back pain tend to have low body image.

Do "central sensitization" questionnaires reflect measures of nociceptive sensitization or psychological constructs? A systematic review and meta-analyses

ABSTRACT

Central sensitization (CS) is defined as an increased nociceptive responsiveness due to sensitization of neurons in the central nervous system, usually the result of prolonged nociceptive input or a disease state associated with noxious inputs (eg, polyarthritis). The concept of CS has recently been adopted in clinical assessments of chronic pain, but its diagnosis in humans may now include a wide range of hypervigilant responses. The purpose of this review is to ascertain whether self-report questionnaires linked with CS are associated with enhanced nociceptive responses or whether they measure sensitivity in a broader sense (ie, emotional responses). According to our published, PROSPERO-registered review protocol (CRD42021208731), a predefined search of studies that involve the Central Sensitization Inventory (CSI) or Pain Sensitivity Questionnaire (PSQ), correlated with either nociceptive sensory tests or emotional hypervigilance was conducted on MEDLINE, PsycINFO, and Web of Science. Correlations between the CSI or PSQ with our primary outcomes were extracted and meta-analysed. A review of 66 studies totalling 13,284 participants found that the CSI (but not the PSQ) strongly correlated with psychological constructs: depression, anxiety, stress, pain catastrophising, sleep, and kinesiophobia. The CSI and PSQ showed weak or no correlations with experimental measures of nociceptive sensitivity: pain thresholds, temporal summation, or conditioned pain modulation. The PSQ did, however, correlate strongly with phasic heat and tonic cold pain tests. The studies reviewed did not provide sufficient evidence that self-report measures reflect a canonical understanding of CS. The CSI more closely reflects psychological hypervigilance than increased responsiveness of nociceptive neurons.

Associations of Central Sensitization-Related Symptoms with Low Back Pain-Related Factors and Work Status in Caregivers

Low back pain (LBP) is associated with psychological factors and central sensitization-related symptoms (CSSs). The relationship between CSSs, LBP-related factors, and work status in caregivers remain unclear. This multicentre, collaborative, cross-sectional study aimed to determine the association between CSS severity, LBP-related factors, and work status in caregivers with LBP. We measured LBP intensity, pain duration, pain sites, CSSs (using the Central Sensitization Inventory-9: CSI-9), psychological factors (using the Pain Catastrophizing and Pain Self-Efficacy scales), and work status (interference, amount of assistance, frequency of assistance, and work environment) in 660 caregivers. CSS severity was categorised as no (CSI-9:0−9), mild (CSI-9:10−19), or moderate/severe (CSI-9:20−36). We further performed multiple comparison analyses and adjusted the residual chi-square to reveal differences between CSS severity groups. Caregivers with more severe CSSs tended to exhibit worse LBP intensity (p < 0.01), widespread pain (p < 0.01), catastrophic thinking (p < 0.01), and pain self-efficacy (p < 0.01), and they also tended to experience work interference (p < 0.01). Caregivers without CSSs tended to receive a smaller amount of assistance with a lower frequency (p < 0.05). The number of participants with an adequate environment and equipment was significantly less in the moderate/severe CSS group (p < 0.01). Thus, our findings may suggest that CSS severity is associated with LBP intensity, widespread pain, psychological factors, and work status in caregivers.