Difference in the impact of central sensitization on pain-related symptoms between patients with chronic low back pain and knee osteoarthritis

Central sensitization-related symptoms and their relationship to disability in prevalent chronic musculoskeletal pain: A cross-sectional study

BACKGROUND

Central sensitization (CS) has an important role in chronic musculoskeletal (MSK) pain, which is one of the leading causes of disability worldwide.

OBJECTIVES

To investigate the relationship between CS-related symptoms and disability in chronic MSK pain.

DESIGN

Multi-center cross-sectional survey.

METHODS

Demographic and clinical variables including location, duration, and severity of pain were recorded. In the examination of disability, Istanbul Low Back Pain Disability Index for low back pain, Neck Pain and Disability Scale for neck pain, Quick Disability of the Arm, Shoulder, and Hand for shoulder/upper extremity pain, and Knee Injury and Osteoarthritis Outcome Score for knee pain were used. CS-related symptoms were investigated via the central sensitization inventory (CSI). Based on CSI scores, patient data were compared using the T test and an ANOVA. The association between CSI and selected variables was investigated using Pearson correlation and multivariate regression analysis.

RESULTS

The mean CSI score of five hundred participants was 40.46 (SD: 15.87). Patients with CSI≥40 were found to have higher levels of pain and disability and a poorer quality of life (p < 0.05). In ANOVA, significant differences between groups were observed in CS severity levels for VAS, symptom duration, and all clinical scores (p < 0.01). In the multivariate regression analysis, CSI and VAS scores were found to be related to disability in all pain groups, while pain duration was effective only in the change of knee disability.

CONCLUSION

CS-related symptoms, which are related to increased pain and disability, should be closely monitored in patients with chronic MSK pain.

Temporal relationships between pain, functioning, and human assumed central sensitization in patients with chronic low back pain; a single-case design

BACKGROUND

Interdisciplinary pain rehabilitation (IPR) aims to improve functioning in people with chronic low back pain (CLBP), and is not primary aimed at pain reduction. Many patients however also report a decrease in pain. An explanation could be that IPR results in a decrease in Central Sensitization (CS). As CS is not directly assessable in humans the term Human Assumed Central Sensitization (HACS) is used in this study. It is unknown whether a decrease in HACS precedes a decrease in pain and improved functioning or vice versa.

OBJECTIVES

This study aimed to gain understanding into the temporal relationships between changes in pain, functioning, and HACS in patients with CLBP during IPR.

DESIGN

Longitudinal observational small-N-study.

METHOD

Twelve patients filled in frequently repeated self-reports 1 week before, during the 12-week IPR program, and 2 weeks after IPR. Pain was assessed by Visual Analogue Scale for pain (daily), functioning by Pain Disability Index (weekly) and Work Ability Score (daily), and HACS by Central Sensitization Inventory part A (bi-weekly). Analyses were performed by visual inspection and time series cross-correlation analyses.

RESULTS

Visual inspection showed large fluctuations within and between individual participants in patterns over time. Cross-correlation analyses showed that in most participants, relationships between pain, functioning, and HACS were strongest when analyzed at the same time (55% of comparisons). Strength and direction of (strongest) correlations showed high interindividual variability (neg: 0.33-0.97; pos: 0.22-0.99).

CONCLUSION

Overall, relationships between pain, functioning, and HACS did not show consistent temporality in patients with CLBP.

Establishing central sensitization inventory cut-off values in Dutch-speaking patients with chronic low back pain by unsupervised machine learning

BACKGROUND

Human Assumed Central Sensitization (HACS) is involved in the development and maintenance of chronic low back pain (CLBP). The Central Sensitization Inventory (CSI) was developed to evaluate the presence of HACS, with a cut-off value of 40/100. However, various factors including pain conditions (e.g., CLBP), contexts, and gender may influence this cut-off value. Unsupervised clustering approaches can address these complexities by considering diverse factors and exploring possible HACS-related subgroups. Therefore, this study aimed to determine the cut-off values for a Dutch-speaking population with CLBP based on unsupervised machine learning.

METHODS

Questionnaire data covering pain, physical, and psychological aspects were collected from patients with CLBP and aged-matched healthy controls (HC). Four clustering approaches were applied to identify HACS-related subgroups based on the questionnaire data and gender. The clustering performance was assessed using internal and external indicators. Subsequently, receiver operating characteristic (ROC) analysis was conducted on the best clustering results to determine the optimal cut-off values.

RESULTS

The study included 63 HCs and 88 patients with CLBP. Hierarchical clustering yielded the best results, identifying three clusters: healthy group, CLBP with low HACS level, and CLBP with high HACS level groups. The cut-off value for the overall groups were 35 (sensitivity 0.76, specificity 0.76).

CONCLUSION

This study found distinct patient subgroups. An overall CSI cut-off value of 35 was suggested. This study may provide new insights into identifying HACS-related patterns and contributes to establishing accurate cut-off values.

Central Sensitization-Related Symptoms and Influencing Factors on Health-Related Quality of Life among Frail Older Adults in Senior Day Care Centers: A Cross-Sectional Study

The recent increase in the number of frail older adults has led to increased attention being paid to care services in communities such as senior day care centers. Maintaining health-related quality of life (HRQOL) in frail older adults is important for managing long-term care. The purpose of this study was to comprehensively explore the impact of physical, mental, and cognitive factors, particularly central sensitization-related symptoms (CSSs), on the HRQOL among frail older adults in senior day care centers. HRQOL, physical, mental, and cognitive factors, and severity of CSSs were comprehensively measured using validated methods. Correlation and multiple regression analyses were used to examine factors affecting HRQOL among frail older adults in senior day care centers. The results showed that the timed up and go test significantly affected the HRQOL among frail older adults at senior day care centers. Additionally, knee extension muscle strength, number of pain sites, depressive tendencies, and CSS severity showed a significant negative correlation with HRQOL but were not significant influencing factors. This suggests that functional mobility assessments and approaches are important for maintaining and improving the HRQOL in frail older adults at senior day care centers.

Transcranial Direct Current Stimulation for Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The effects of transcranial direct current stimulation (tDCS) in the treatment of knee osteoarthritis (KOA) is still unclear. The objective is to evaluate the efficacy and safety of tDCS in improving symptoms in patients with KOA.

METHODS

The following electronic databases were searched for eligible randomized controlled trials (RCTs): PubMed, Embase, Web of Science, and the Cochrane Library. The search was performed from the inception dates to April 30, 2023. Data extraction and quality assessment were performed by two independent reviewers. Standard mean differences (SMDs) with 95% confidence intervals (95% CIs) for pooled data were calculated. A random-effects model was used for the data analyses. The primary outcomes were pain and physical function. Secondary outcomes included stiffness, mobility performance, quality of life, pressure pain tolerance, and plasma levels of brain-derived neurotrophic factor (BDNF).

RESULTS

This meta-analysis included 13 RCTs. tDCS was significantly associated with pain decrease compared with sham tDCS (SMD = -0.62, 95% CI -0.87 to -0.37, P < 0.00001). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was no longer a significant association with pain decrease (SMD = -0.45, 95% CI -1.08 to 0.17, P = 0.16). The changes in physical function were not significantly different between the tDCS and sham tDCS groups (SMD = -0.09, 95% CI -0.56 to 0.38, P = 0.71). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was still no significant association with improvement in physical function (SMD = -0.66, 95% CI -1.63 to 0.30, P = 0.18). There was no significant difference with improvement in stiffness (SMD = -0.21, 95% CI -0.77 to 0.34, P = 0.45), mobility performance (SMD = 4.58, 95% CI -9.21 to 18.37, P = 0.51), quality of life (SMD = -7.01, 95% CI -22.61 to 8.59, P = 0.38), and pressure pain tolerance (SMD = 0.30, 95% CI -0.09 to 0.69, P = 0.13). There was a statistically significant reduction in plasma levels of BDNF (SMD = -13.57, 95% CI -24.23 to -2.92, P = 0.01).

CONCLUSION

In conclusion, tDCS could significantly alleviate pain, but it might have no efficacy in physical function, stiffness, mobility performance, quality of life, and pressure pain tolerance among patients with KOA.

The Influence of Physical, Mental, and Cognitive Factors on Health-Related Quality of Life among Community-Dwelling Older Adults: A Focus on Central Sensitization-Related Symptoms

Most older adults wish to maintain independence in their familiar communities. However, many experience pain and pain-related disabilities which reduce their health-related quality of life (HRQOL), leading to increased hospitalizations and mortality. This study aimed to determine the impact of physical, mental, and cognitive factors, particularly central sensitization-related symptoms (CSS), on the HRQOL of community-dwelling older adults. A total of 206 participants were included in the analysis, which measured HRQOL, basic attributes, physical functions and body pain, mental factors, cognitive factors, and CSS severity using validated tools. A correlation analysis was used to examine the association between HRQOL and each measure. Furthermore, multiple regression analysis (forced entry method) was performed to identify the factors influencing the HRQOL. The study found that pain intensity and CSS severity significantly influenced the HRQOL among community-dwelling older adults. The higher the pain intensity and CSS severity, the lower their HRQOL. The participants had mild pain and CSS, demonstrating the need to monitor, address, and treat even non-severe issues in community-dwelling older adults. This association, revealed for the first time in this study, suggests that approaches to reduce pain and CSS are important for maintaining and improving the HRQOL of community-dwelling older adults.

Pathology of knee osteoarthritis pain: contribution of joint structural changes and pain sensitization to movement-evoked pain in knee osteoarthritis

Introduction

Movement-evoked pain (MEP) is the primary symptom in patients with knee osteoarthritis (KOA).

Objectives

This study aimed to investigate the contribution of joint structural changes and pain sensitization to the mechanisms of MEP in patients with KOA.

Methods

A total of 86 patients were assessed for demographic characteristics, osteoarthritis severity, Whole-Organ Magnetic Resonance Imaging Score-Hoffa synovitis and bone marrow lesions, pressure pain threshold and temporal summation of pain at the knee and forearm, Central Sensitization Inventory-9, and MEP. In measure of MEP, knee pain was scored using a numerical rating scale (NRS, 0-10) before and every minute during a 6-minute walking test (6MWT), and the MEP index was defined as the change in NRS pain score from baseline to the sixth minute of walking.

Result

On average, pain during 6MWT increased by 1.4 ± 1.5 points on the NRS relative to baseline, with 30.2% of patients showing an increase of 2 points or more. The hierarchical linear regression analysis revealed that Hoffa synovitis, pressure pain threshold at the forearm, and temporal summation of pain at the knee were associated with the MEP index.

Conclusion

The findings of this study suggest that both synovitis and neural mechanisms, such as pain sensitization, play a role in the development of MEP in KOA.

Low central sensitisation inventory score is associated with better post-operative outcomes of osteotomy around the knee

PURPOSE

The purpose of this study was to investigate the potential association between central sensitisation inventory (CSI) scores and post-operative patient-reported outcomes (PROs) in patients underwent osteotomy around the knee (OAK), with a CSI cut-off score specific for knee osteoarthritis.

METHODS

CSI scores were collected from 173 patients who underwent OAK, along with their knee injury and osteoarthritis outcome score (KOOS) and pain numeric rating scale (NRS) scores. Patients were divided into high-CSI score group and low-CSI score group with a cut-off score of 17. Multivariate linear regression was performed to test the association between CSI scores and post-operative outcomes. Pre-surgery KOOS and NRS scores and the rate of attainment of minimal clinically important difference (MCID) of KOOS scores was analysed as secondary outcomes.

RESULTS

Low-CSI score group had significantly higher post-operative KOOS scores and lower pain NRS scores compared to the high-CSI score group (< p = 0.01) after adjusting for confounding factors. For pre-operative scores, only the KOOS-Symptom score was significantly different between the groups (64.7 ± 20.1 when CSI < 17 vs.55.1 ± 19.7 when CSI ≥ 17; p = 0.008). The low-CSI score group had significantly higher MCID achievement rates of KOOS-Pain, Symptom, and ADL than the high-CSI score group (86% vs. 68%; 74% vs. 55%; 86% vs. 67%, respectively; P < 0.05).

CONCLUSIONS

This study established an association between post-operative CSI scores ≥ 17 and poorer outcomes following OAK, highlighting the potential value of the CSI in identifying patients in need of more comprehensive peri-operative pain management.

LEVEL OF EVIDENCE

Level III. Retrospective comparative study.

Central sensitization as a predictive factor for the surgical outcome in patients with lumbar spinal stenosis: a multicenter prospective study

PURPOSE

The impact of central sensitization (CS) on neurological symptoms and surgical outcomes in patients with lumbar spinal stenosis (LSS) remains unknown. This study aimed to investigate the influence of preoperative CS on the surgical outcomes of patients with LSS.

METHODS

A total of 197 consecutive patients with LSS (mean age 69.3) who underwent posterior decompression surgery with or without fusion were included in this study. The participants completed the CS inventory (CSI) scores and the following clinical outcome assessments (COAs) preoperatively and 12 months postoperatively: the Japanese Orthopaedic Association (JOA) score for back pain, JOA back pain evaluation questionnaire, and Oswestry Disability Index (ODI). The association between preoperative CSI scores and preoperative and postoperative COAs was analyzed, and postoperative changes were statistically evaluated.

RESULTS

The preoperative CSI score significantly decreased at 12 months postoperatively and was significantly correlated with all COAs preoperatively and 12 months postoperatively. Higher preoperative CSI showed worse postoperative COAs and inferior postoperative improvement rates in the JOA score, VAS score for neurological symptoms, and ODI. Multiple regression analysis demonstrated that preoperative CSI was significantly associated with postoperative low back pain (LBP), mental health, quality of life (QOL), and neurological symptoms at 12 months postoperatively.

CONCLUSIONS

Preoperative CS evaluated by CSI had a significantly worse impact on surgical outcomes, including neurological symptoms, disability, and QOL, especially related to LBP and psychological factors. CSI can be used clinically as a patient-reported measure for predicting postoperative outcomes in patients with LSS.

Association of central sensitization, visceral fat, and surgical outcomes in lumbar spinal stenosis

BACKGROUND

Controversy remains regarding predictors of surgical outcomes for patients with lumbar spinal stenosis (LSS). Pain sensitization may be an underlying mechanism contributing to LSS surgical outcomes. Further, obesity is associated with dissatisfaction and poorer outcomes after surgery for LSS. Therefore, this study aimed to examine the relationship between central sensitization (CS), visceral fat, and surgical outcomes in LSS.

METHODS

Patients with LSS were categorized based on their central sensitization inventory (CSI) scores into low- (CSI < 40) and high- (CSI ≥ 40) CSI subgroups. The participants completed clinical outcome assessments preoperatively and 12 months postoperatively.

RESULTS

Overall, 60 patients were enrolled in the study (28 men, 32 women; mean age: 62.1 ± 2.8 years). The high-CSI group had significantly higher mean low back pain (LBP), leg pain, and leg numbness visual analogue scale (VAS) scores than the low-CSI group (p < 0.01). The high-CSI group had a significantly higher mean visceral fat area than the low-CSI group (p < 0.01). Postoperatively, LBP VAS score was significantly worse in the high-CSI group. Relative to preoperatively, postoperative leg pain and leg numbness improved significantly in both groups.

CONCLUSIONS

We believe that neuro decompression can be effective for LSS surgical outcomes in patients with CS; nonetheless, it should be approached with caution owing to the potential for worsening LBP. Additionally, visceral fat is an important indicator suggesting the involvement of CS.

Impact of central sensitization on pain, disability and psychological distress in patients with knee osteoarthritis and chronic low back pain

BACKGROUND

Central sensitization (CS) is becoming increasingly recognized as a significant factor in many chronic pain conditions, including knee osteoarthritis (KOA) and chronic low back pain (CLBP). Yet it presently remains unclear how strong is the involvement of CS in KOA and CLBP and which factors are involved in CS in these two chronic disabling diseases.

METHODS

This is a cross-sectional study in which included a total of 178 patients with KOA and 118 patients with CLBP. Inclusion criteria for eligible participants for the KOA group were a confirmed diagnosis of KOA according to the American College of Rheumatology criteria, and for the CLBP group a chronic low back pain for more than 3 months. Subjects were excluded if they presented with a diagnosed psychiatric disorder or if they lacked the capacity to provide informed consent, understand study questionnaires or perform physical performance tests. In each group, were assessed; CS-related symptoms using the Central Sentization Inventory (CSI); demographic and clinical characteristics such as disease duration, pain intensity on a visual analog scale, self-reported function using the Lequesne index for KOA patients and the Oswestry Disability index for CLBP patients, and physical performance with the 6 minutes' walk test; as well as psychosocial risk factors using the Patient Health Questionnaire for depression (PHQ-9), the Generalized Anxiety Disorder (GAD-7) and the Pain Catastrophizing Scale (PCS).

RESULTS

CSI scores significantly correlated with pain intensity and disability in KOA and CLBP patients, and were highly correlated with self-reported symptoms of depression, anxiety and pain catastrophizing. Depression significantly predicted the CSI score in both groups.

CONCLUSION

These findings provide further evidence for the impact of CS on pain, function and physical performance in KOA and CLBP patients. Psychosocial symptoms such as pain catastrophizing, anxiety and depression should also be considered as they are also associated with CS.

Evaluation of Central Sensitization Inventory in Patients Undergoing Elective Spine Surgery in a Multicenter Study

STUDY DESIGN

This study is a retrospective review.

OBJECTIVE

Central sensitization (CS) is a neurological phenomenon that involves hypersensitivity of the central nervous system. The central sensitization inventory (CSI) was developed as a screening tool to assess CS-related symptoms. The purpose of this study was to evaluate the association of preoperative CSI scores with patient-reported outcome measures (PROMs) including neurological symptoms for patients who underwent spine surgeries in a multicenter study.

METHODS

A consecutive 673 patients who underwent spine surgery at 8 different institutions were included in this study. Preoperative CSI scores were assessed for all subjects. The participants completed the following PROMs: the Oswestry Disability Index (ODI), the Japanese Orthopaedic Association (JOA) back pain evaluation questionnaire (JOABPEQ) for lumbar spinal diseases, and the JOA cervical myelopathy evaluation questionnaire (JOACMEQ) for cervical spinal diseases. The association of CSI scores with PROMs was statistically evaluated.

RESULTS

The average CSI score for the total subjects was 23.6 ± 13.5. The subjects with CS-related symptoms (CSI ≥ 40) were 13.2% (n = 89). The CSI score showed a significant and weak-to-moderate correlation with the PROMs including neurological symptoms that included all the domains of the JOACMEQ for cervical spinal diseases, and JOABPEQ and ODI for lumbar spinal diseases. Among these, psychological factors had the most influence on the correlation with CSI score.

CONCLUSION

Central sensitization evaluated by the CSI is related to neurological symptoms and health-related quality of life in patients undergoing elective spine surgery.

Validity of the Central Sensitization Inventory to Address Human Assumed Central Sensitization: Newly Proposed Clinically Relevant Values and Associations

Central sensitization cannot be directly demonstrated in humans and thus a gold standard is missing. Therefore, we used human assumed central sensitization (HACS) when associated with humans. The central sensitization inventory (CSI) is a screening questionnaire for addressing symptoms that are associated with HACS. This cross-sectional study compared patients with chronic pain and at least one central sensitivity syndrome with healthy, pain-free controls via ROC analyses. Analyses were performed for all participants together and for each sex separately. Regression analyses were performed on patients with chronic pain with and without central sensitivity syndromes. Based on 1730 patients and 250 healthy controls, cutoff values for the CSI for the total group were established at 30 points: women: 33 points; men: 25 points. Univariate and multivariate regression analyses were used to identify possible predictors for the CSI score in 2890 patients with chronic pain. The CSI score is associated with all independent factors and has a low association with pain severity in women and a low association with pain severity, age, and body mass index in men. The newly established CSI cutoff values are lower than in previous studies and different per sex, which might be of clinical relevance in daily practice and importance in research.

Polygenic Contributions to Chronic Overlapping Pain Conditions in a Large Electronic Health Record Sample

Chronic overlapping pain conditions (COPCs) are believed to share common etiological mechanisms involving central sensitization. Genetic and environmental factors putatively combine to influence susceptibility to central sensitization and COPCs. This study employed a genome-wide polygenic risk score approach to evaluate genetic influences on 8 common COPCs. COPCs were identified by International Classification of Disease codes in Vanderbilt's deidentified clinical biorepository (BioVU), with each COPC condition empirically weighted for the level of central sensitization based on prior work. A centralized pain score (CPS) was calculated for 55,340 individuals by summing the weighted number of COPCs. Overall, 12,502 individuals (22.6%) were diagnosed with at least 1 COPC, with females exhibiting nearly twice the mean CPS as males. To assess the genetic influence on centralized pain in COPCs, 6 pain polygenic risk scores (PRSs) were developed using UK Biobank data to predict 6 pain criteria (no pain, neck/shoulder, abdomen, hip, knee, low back pain). These PRSs were then deployed in the BioVU cohort to test for association with CPS. In regression models adjusted for age, sex, and BMI, all pain PRSs except hip pain were significantly associated with CPS. Our findings support a shared polygenic influence across COPCs potentially involving central sensitization mechanisms. PERSPECTIVE: This study used a polygenic risk score approach to investigate genetic influences on chronic overlapping pain conditions. Significant findings in this study provide evidence supporting previous hypotheses that a shared polygenic influence involving central sensitization may underly chronic overlapping pain conditions and can guide future biomarker and risk assessment research.

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.

Association of the Degree of Varus Thrust during Gait Assessed by an Inertial Measurement Unit with Patient-Reported Outcome Measures in Knee Osteoarthritis

This study aimed to assess the association between the degree of varus thrust (VT) assessed by an inertial measurement unit (IMU) and patient-reported outcome measures (PROMs) in patients with knee osteoarthritis. Seventy patients (mean age: 59.8 ± 8.6 years; women: n = 40) were instructed to walk on a treadmill with an IMU attached to the tibial tuberosity. For the index of VT during walking (VT-index), the swing-speed adjusted root mean square of acceleration in the mediolateral direction was calculated. As the PROMs, the Knee Injury and Osteoarthritis Outcome Score were used. Data on age, sex, body mass index, static alignment, central sensitization, and gait speed were collected as potential confounders. After adjusting for potential confounders, multiple linear regression analysis revealed that the VT-index was significantly associated with the pain score (standardized β = -0.295; p = 0.026), symptoms score (standardized β = -0.287; p = 0.026), and activities of the daily living score (standardized β = -0.256; p = 0.028). Our results indicated that larger VT values during gait are associated with worse PROMs, suggesting that an intervention to reduce VT might be an option for clinicians trying to improve PROMs.

Soft-Tissue Mobilization and Pain Neuroscience Education for Chronic Nonspecific Low Back Pain with Central Sensitization: A Prospective Randomized Single-Blind Controlled Trial

This study was conducted to demonstrate the therapeutic effect of soft-tissue mobilization (STM) combined with pain neuroscience education (PNE) for patients with chronic nonspecific low back pain with central sensitization. A total of 28 participants were recruited and randomly allocated to either the STM group (SMG) (n = 14) or the STM plus PNE group (BG; blended group) (n = 14). STM was applied twice a week for four weeks, with a total of eight sessions, and PNE was applied within four weeks, for a total of two sessions. The primary outcome was pain intensity, and the secondary outcomes were central sensitization, pressure pain, pain cognition, and disability. Measurements were made at baseline, after the test, and at 2-week and 4-week follow-ups. The BG showed significant improvement in pain intensity (p < 0.001), pressure pain (p < 0.001), disability (p < 0.001), and pain cognition (p < 0.001) compared to the SMG. This study demonstrated that STM plus PNE is more effective for all measured outcomes compared to STM alone. This finding suggests that the combination of PNE and manual therapy has a positive effect on pain, disability index, and psychological factors in the short term.

The relationship between the Keele STarT back screening tool, the short form of central sensitivity inventory and health-related quality of life in patients with low back pain

INTRODUCTION

It has been reported that the scores of the Keele STarT Back Screening Tool (SBST) and the short form of Central Sensitization Inventory (CSI-9) are associated with Health-Related Quality of Life (HRQoL) in patients with low back pain (LBP). However, it is unclear which screening tool is more associated with HRQoL in patients with LBP.

OBJECTIVE

To identify which SBST and CSI-9 are more related to HRQoL and investigate the association between SBST and CSI-9 scores.

STUDY DESIGN

Cross-sectional study.

METHOD

A multiple regression analysis was conducted to examine the factors associated with the HRQoL using age, pain intensity, disability, SBST score, and CSI-9 score as independent variables. Spearman's rank correlation coefficient was also conducted to determine the association between SBST and CSI-9 score.

RESULTS

Multiple regression analysis revealed that the Oswestry Disability Index (ODI) score (p < 0.01, β = -0.62, VIF = 1.70) and SBST score (p < 0.01, β = -0.32, VIF = 1.86) were significant associated variables. A significant association was found between SBST and CSI-9 scores (p < 0.01, ρ = 0.47).

CONCLUSION

The results showed that in patients with LBP the association of HRQoL with SBST was more substantial than with CSI-9.

Associations between visceral fat chronic low back pain and central sensitization in patients with lumbar spinal stenosis

BACKGROUND

Pain sensitization may be one of the mechanisms contributing to chronic low back pain (CLBP).

OBJECTIVE

To evaluate the association between visceral fat, CLBP, and central sensitization (CS); describe the relationship between low back pain (LBP) intensity and CS; and identify possible correlation between visceral fat and LBP intensity.

METHODS

Patients with CLBP were divided using their CS inventory (CSI) scores into low- (CSI < 40) and high-CSI (CSI ⩾ 40) subgroups. We compared computed tomography (CT) measurements and scores for association with pain according to the visual analogue scale (VAS) between the two groups.

RESULTS

The low-CSI and the high-CSI groups had 47 patients (67.1%; 21 men, 26 women) and 23 patients (32.9%; 11 men and 12 women), respectively. The high-CSI group had a significantly higher mean VAS score (p< 0.01) and estimated mean visceral fat area (p< 0.05) than the low-CSI group. There was a moderate positive correlation between VAS score and visceral fat (standardised partial regression coefficient: 0.659, p< 0.01) in the high-CSI group according to multiple linear regression analysis adjusted for age and sex.

CONCLUSIONS

Visceral fat is associated with CLBP, regardless of sex or age, and may be a potential therapeutic target for CLBP with CS.

Differences in outcomes after total hip arthroplasty for osteoarthritis between patients with and without central sensitivity syndromes other than fibromyalgia

We investigated the differences in outcomes after total hip arthroplasty (THA) for hip osteoarthritis (HOA) between patients with and without central sensitivity syndromes (CSSs) other than fibromyalgia (FM). After excluding two patients with FM, we compared the clinical data of 41 patients with CSSs and 132 patients without CSSs. Clinical data included scores on the central sensitization inventory, visual analog scale for pain (VAS pain), and Japanese Orthopedic Association Hip Disease Evaluation Questionnaire (JHEQ). VAS pain was significantly higher at 3 and 6 months after THA in patients with CSSs than in those without CSSs (3 and 6 months, P < 0.001). Satisfaction, pain, and mental JHEQ scores were lower in patients with CSSs than in those without CSSs (satisfaction, P < 0.001; pain, P = 0.011; mental, P = 0.032). Multiple regression analyses indicated that one and ≥ 2 CSS diagnoses significantly impacted the satisfaction score (one CSS, β = − 0.181, P = 0.019; ≥ 2 CSSs, β = − 0.175, P = 0.023). Two or more CSSs were the only factor influencing the pain score (β = − 0.175, P = 0.027). Pain in patients with CSSs reflects central sensitization, which may adversely affect post-operative outcomes. Surgeons should pay attention to patients with a history of CSSs diagnoses who undergo THA for HOA.

Pain Sensitization and Neuropathic Pain-like Symptoms Associated with Effectiveness of Exercise Therapy in Patients with Hip and Knee Osteoarthritis

Pain sensitization and neuropathic pain-like symptoms are some of the common pain symptoms in patients with lower limbs, including hip and knee, osteoarthritis (HOA/KOA). Exercise therapy has been the first-line treatment; however, the effects differ for each patient. This prospective cohort study investigated the relationship between the effectiveness of exercise therapy and pretreatment characteristics (radiologic severity, pain sensitization, and neuropathic pain-like symptoms) of patients with HOA/KOA. We assessed the pain intensity using a numerical rating scale (NRS) before and after 12 weeks of exercise therapy in patients with HOA/KOA (n = 101). Before treatment, the Kellgren–Lawrence (K-L) grade; minimum joint space width (mJSW); pressure pain threshold (PPT) and temporal summation of pain (TSP) at the affected joint, tibia, and forearm; Central Sensitization Inventory-9; and painDETECT questionnaire (PDQ) were assessed. Cluster analysis was based on the pretreatment NRS and change in NRS with exercise therapy to identify the subgroups of pain reduction. The pretreatment characteristics of each cluster were compared. According to the results of the cluster analyses, patients in cluster 1 had severe pain that did not improve after exercise therapy, patients in cluster 2 had severe pain that improved, and those in cluster 3 had mild pain that improved. The patients in cluster 1 exhibited lower PPT at all measurement sites, higher TSP at the affected joint, and higher PDQ scores than those in other clusters. There was no difference in the K-L grade and mJSW among the clusters. The subgroup with severe pain and pain sensitization or neuropathic pain-like symptoms at pretreatment, even with mild joint deformity, may have difficulty in achieving improvement in pain after 12 weeks of exercise therapy. These findings could be useful for prognosis prediction and for planning exercise therapy and combining with other treatment.

"Convergent validity of the central sensitization inventory and experimental testing of pain sensitivity"

OBJECTIVES

The aim of the current study was to examine the convergent validity of the Central Sensitization Inventory by quantifying the correlation with experimental measures of pain sensitivity and self-reported psycho-social questionnaires, in a low back pain population.

METHODS

All participants were recruited from an outpatient hospital spine care clinic (Spine Centre of Southern Denmark). Participants underwent a standardized experimental pain test protocol and completed the Central Sensitization Inventory (CSI) along with additional self-reported questionnaires to assess psycho-social constructs across different domains. The association between the CSI, experimental pain measures and other self-reported psycho-social questionnaires were analyzed using correlation and contingency tests. ROC-curve analysis was used to determine sensitivity and specificity for CSI.

RESULTS

One hundred sixty-eight (168) participants were included. The CSI was weakly correlated with nine out of 20 variables in the experimental pain test protocol (rho range -0.37 to 0.22). The CSI was more closely correlated with psycho-social factors such as work ability, disability, and symptoms of exhaustion disorder. ROC-analysis identified an optimal cut-point of 44 on CSI (Sn=39.1% Sp=87.4%). The CSI had an area under the ROC curve of 0.656. Fisher's exact test demonstrated a statistically significant association between participants scoring ≥40 on CSI and participants categorized as sensitized by experimental pain tests (p-value=0.03).

CONCLUSIONS

Our findings are consistent with previous studies, indicating that the CSI is related to psycho-social constructs. However, the convergent validity with experimental pain measures is small and probably not clinically meaningful.

Impact of pain sensitisation on the quality of life of patients with knee osteoarthritis

Objectives

We aim to evaluate the effect on different ways of classifying pain sensitisation on impact and quality of life (QoL) in knee osteoarthritis (KOA).

Methods

We used baseline data from a cohort of consecutive patients with KOA listed for arthroplasty. We collected demographics and number of painful body sites. We measured pressure pain thresholds at the right forearm (PPT_arm). Pain sensitisation was classified using: (1) widespread pain, (2) lowest 10th percentile of PPT_arm and (3) PainDETECT questionnaire ≥13/38. Impact and QoL were assessed using Western Ontario and McMaster Universities Osteoarthritis Index and Short Form-36. Impact and QoL scores in patients with or without pain sensitisation were compared. We evaluated the association of pain sensitisation measures with QoL scores using multivariable regression.

Results

233 patients (80% female, mean age 66 years) included in the analysis; 7.3%, 11.6% and 4.7% were classified as having pain sensitisation by widespread pain, low PPT_arm and PainDETECT criteria, respectively. There was minimal overlap of patients as classified as pain sensitisation phenotype by different measures. Patients with pain sensitisation had poorer QoL compared with those without. Low PPT_arm identified patients with poorer general health, while widespread pain and PainDETECT identified poorer QoL in more psychological domains. There was weak correlation between number of painful body sites and PainDETECT (rho=0.23, p<0.01), but no significant correlation with PPT_arm.

Conclusion

Patients with KOA with pain sensitisation have poorer QoL compared with those without, regardless of classification method. Different criteria defined patients with different pattern of QoL impact.

Pain descriptors and determinants of pain sensitivity in knee osteoarthritis: a community-based cross-sectional study

Objectives

To explore pain characteristics in individuals with knee osteoarthritis (KOA), to compare pain sensitivity across individuals with KOA, chronic back pain (CBP) and pain-free individuals (NP), and to examine the relationship between clinical and pain characteristics with pain sensitivity in KOA.

Methods

Cross-sectional, community-based online survey. Two datasets were combined comprising Dutch individuals of ≥ 40 years of age, experiencing chronic knee pain (KOA, N = 445), chronic back pain (CBP, N = 504), or no pain (NP, N = 256). Demographic and clinical characteristics, global health, physical activity/exercise, and pain characteristics including intensity, spreading, duration, quality (SF-MPQ), and sensitivity (PSQ) were assessed. Differences between (sub)groups were examined using analyses of variance or Chi-square tests. Regression analyses were performed to examine determinants of pain sensitivity in the KOA group.

Results

Quality of pain was most commonly described as aching, tender, and tiring-exhausting. Overall, the KOA group had higher levels of pain sensitivity compared to NP group, but lower levels than the CBP group. Univariately, pain intensity, its variability and spreading, global health, exercise, and having comorbidities were weakly related to pain sensitivity (standardized betas: 0.12-0.27). Symptom duration was not related to pain sensitivity. Older age, higher levels of continuous pain, lower levels of global health, and exercise uniquely contributed, albeit modest, to pain sensitivity (P&lt;0.05).

Conclusion

Continuous pain such as aching and tenderness in combination with decreased physical activity may be indicative for a subgroup of individuals at risk for pain sensitivity and, ultimately, poor treatment outcomes.

Characteristics of clusters with contrasting relationships between central sensitization-related symptoms and pain

The central sensitization inventory (CSI) evaluates the central sensitization (CS)-related symptoms associated with increased pain sensitivity. However, the CSI includes items that are not directly related to pain. In this study, 146 patients with pain were classified into subgroups by k-means cluster analysis based on the short form of the central sensitization inventory (CSI9) and pain scores. In addition, inter-group and multiple comparisons were performed to examine the characteristics of each group. As a result of this study, there were three subgroups (clusters 1, 2, and 3) in which the CSI9 and pain intensity were both low, moderate, and high, and one subgroup (cluster 4) in which only CSI9 was high and pain intensity was low. Two subgroups with high CSI9 scores but contrasting pain intensities (clusters 3 and 4) were extracted; the pattern of CS-related symptoms in these two groups was very similar, with no differences in most of the non-pain factors. It is necessary to consider these points when interpreting the clinical condition of a patient with pain when using the assessment of CS-related symptoms.

The Definition, Assessment, and Prevalence of (Human Assumed) Central Sensitisation in Patients with Chronic Low Back Pain: A Systematic Review

Central sensitisation is assumed to be one of the underlying mechanisms for chronic low back pain. Because central sensitisation is not directly assessable in humans, the term 'human assumed central sensitisation' (HACS) is suggested. The objectives were to investigate what definitions for HACS have been used, to evaluate the methods to assess HACS, to assess the validity of those methods, and to estimate the prevalence of HACS. Database search resulted in 34 included studies. Forty different definition references were used to define HACS. This review uncovered twenty quantitative methods to assess HACS, including four questionnaires and sixteen quantitative sensory testing measures. The prevalence of HACS in patients with chronic low back pain was estimated in three studies. The current systematic review highlights that multiple definitions, assessment methods, and prevalence estimates are stated in the literature regarding HACS in patients with chronic low back pain. Most of the assessment methods of HACS are not validated but have been tested for reliability and repeatability. Given the lack of a gold standard to assess HACS, an initial grading system is proposed to standardize clinical and research assessments of HACS in patients with a chronic low back.

Central sensitization in burning mouth syndrome: a practical approach using questionnaires

OBJECTIVES

Some experts have suggested that burning mouth syndrome (BMS) should be included in the family of central sensitivity syndromes, a group of similar medical disorders linked by the central sensitization (CS) mechanism. Our objective is to assess the presence of CS in patients with BMS by performing a clinical examination and administering questionnaires to measure the generalized extent of pain, the presence of associated symptoms, and the number of other concurrent chronic pain conditions.

STUDY DESIGN

We conducted a case-control study in 82 subjects (40 patients with BMS and 42 controls). Patients with BMS were diagnosed using The International Classification of Headache Disorders 3rd edition, beta version (ICHD-IIIβ) criteria. The Widespread Pain Index (WPI) and Symptom Severity (SS) Score questionnaires were used to determine the degree of central sensitivity. The number of other concurrent chronic pain conditions was determined with the Neblett inventory.

RESULTS

Data indicative of CS show a statistically significant association with BMS. Both SS Score and Widespread Pain Index scores higher in patients with BMS. Additionally, patients with BMS reported a significantly higher number of other central sensitivity syndromes.

CONCLUSIONS

Patients with BMS could present a CS component as well as other chronic pain conditions. The use of questionnaires may be useful to determine the degree of central sensitivity in patients with BMS.

Influence of pain-related psychological factors on therapeutic outcomes in patients with chronic low back pain after oxygen-ozone treatment: a case-series

The aim of the study was to identify the variables related to therapeutic success of intramuscular oxygen-ozone (O2O3) in patients with chronic low back pain (LBP). Twenty-one patients underwent an eight-session intramuscular-paravertebral O2O3 treatment with a weekly frequency. Numeric Rating Score for pain (NRSp), anxiety (NRSa), mood (NRSm), Oswestry Disability Index (ODI) and Physical and Mental Component Summary scores (PCS and MCS) of Short Form 12 (SF-12) were assessed baseline, after the treatment and at six-months follow-up. The ODI and NRSp scores showed significant improvement at the end of the treatment: the improvement in pain was maintained also at 6 months’ follow-up. A significant correlation between baseline NRSa and the variation of the NRSp and ODI was observed. There was a correlation between NRSm at baseline and the variation of the ODI. A moderate correlation between MCS-12 at baseline and the variation of the NRSp score was found. Surprisingly, patients with a more compromised psychological well-being due to LBP had better results after oxygen-ozone therapy. Therefore, NRSa, NRSm and MCS-12 scores could be useful predictors of good therapeutic outcome.

Central Sensitization in Chronic Low Back Pain: A Population-Based Study of a Japanese Mountain Village

Purpose

Central sensitization (CS) is defined as the increased responsiveness of nociceptive neurons in the central nervous system to normal or subthreshold afferent input. CS has been proposed as an underlying mechanism of chronic pain in musculoskeletal disorders including low back pain (LBP). A Central Sensitization Inventory (CSI) has recently been developed for screening participants with CS. However, the association of CS with chronic LBP (cLBP) in the general population remains unknown. The purpose of this study was to investigate the association of CS with cLBP using the CSI in a population-based cohort of a Japanese mountain village.

Participants and Methods

Participants aged more than 50 years were recruited from the inhabitants of a mountain village in Japan. Participants completed the following patient-reported outcome measures. Severity of CS was assessed by the CSI. LBP intensity was measured on a numerical rating scale (NRS). Health-related quality of life (QOL) was measured using the EuroQol 5-dimension (EQ-5D), EuroQol-visual analogue scales (EQ-VAS), and the Oswestry Disability Index (ODI). The association of CS and each parameter was statistically evaluated.

Results

A total of 272 participants (average age: 72.1 years-old) were analyzed in this study, and 28.3% had cLBP. Average NRS, ODI and CSI scores were significantly higher in the cLBP group than in the without LBP (LBP-) group. There was a significant correlation between CSI and NRS scores (r=0.34, P<0.0001), ODI (r=0.60, P<0.0001), EQ5D (r=-0.55, P<0.0001) and EQ-VAS (r=-0.52, P<0.0001). A multiple regression analysis identified that ODI, EQ-VAS and age were factors significantly associated with CSI.

Conclusion

The results of this study suggest that CS is involved in the pathological condition of cLBP in the local residents of a Japanese mountain village.

Combination of Pain Location and Pain Duration is Associated with Central Sensitization-Related Symptoms in Patients with Musculoskeletal Disorders: A Cross-Sectional Study

OBJECTIVES

Increased evidence indicates that pain location affects central sensitization (CS)-related symptoms. In addition, pain location and pain duration may be intricately related to CS-related symptoms. However, these factors have been investigated separately. This study aimed to investigate the association between CS-related symptoms and pain location and/or pain duration in patients with musculoskeletal disorders.

METHODS

Six hundred thirty-five participants with musculoskeletal disorders were included in this cross-sectional study. All participants were assessed for pain location, pain duration, central sensitization inventory (CSI), EuroQol-5 dimension, and brief pain inventory. The participants were categorized into 3 groups based on pain location (spinal, limb, and both spinal and limb pain) and into 2 groups based on pain duration (acute and chronic pain).

RESULTS

The interaction between pain location and pain duration were not significant on CSI score (P > 0.05). The odds ratio for higher CSI score (≥ 40) in patients with both spinal and limb pain vs. those with spinal or limb pain was 2.64 (P < 0.01) and that in patients with chronic pain vs. those with acute pain was 1.31 (P = 0.52). In addition, the prevalence of higher CSI scores in the combination of chronic and "both spinal and limb" pain was high (23.1%, adjusted residual = 4.48).

CONCLUSIONS

Pain location independently influenced CSI scores, and the combination of both spinal and limb pain and chronic pain indicated high CSI scores. The combination of pain location and pain duration is an important clue that points to CS-related symptoms.

Quantitative Sensory Testing Discriminates Central Sensitization Inventory Scores in Participants with Chronic Musculoskeletal Pain: An Exploratory Study

BACKGROUND

The Central Sensitization Inventory (CSI) is often used in clinical settings to screen for the presence of central sensitization. However, various cutoff scores have been reported for this tool, and scores have not been consistently associated with widespread pain sensitivity as measured with quantitative sensory testing (QST). The purpose of this study was to compare QST profiles among asymptomatic controls and participants with chronic musculoskeletal pain (CMP), and to determine the association between self-report questionnaires and QST in participants with CMP.

METHODS

Twenty asymptomatic controls and 46 participants with CMP completed the CSI, PROMIS-29, and QST assessments of mechanical and thermal pain thresholds remote to the area of pain. Receiver Operating Characteristic analysis revealed a cutoff score of 33.5 for the CSI. PROMIS-29 Quality of Life (QOL) inventory and QST measures were compared between low and high CSI groups.

RESULTS

The high CSI group (n = 19) had significantly lower mechanical and thermal pain thresholds, and larger impairments in QOL measures, compared to the low CSI group (n = 27) and asymptomatic controls. Participants with CSI scores < 33.5 presented similarly to asymptomatic controls. Anxiety, pain interference, and CSI scores demonstrated the highest number of significant associations to QST measures.

CONCLUSION

A cutoff score of 33.5 on the CSI may be useful for discriminating widespread pain sensitivity and quality of life impairments in participants with CMP. Future studies should consider how the presence of high or low CSI may impact differential diagnosis, prognosis, and treatment responsiveness for patients with primary or secondary CMP.

Evaluation of the Central Sensitization Inventory Score in elderly adults with musculoskeletal examination

OBJECTIVES

The present study aimed to conduct an epidemiological survey of Central Sensitization Inventory (CSI) scores in an older adult population and to investigate the association between the CSI scores, age, sex, pain intensity, site of pain, and health-related quality of life (QOL).

METHODS

Participants were 373 Japanese adults aged ≥ 50 years who underwent a health checkup in 2018. We collected demographic data and clinical characteristics along with the CSI scores, QOL questionnaire, site of pain (neck, lower back, upper limb, and lower limb) and pain severity. We performed an epidemiological survey of the CSI scores and investigated the gender difference in CSI scores and the relationship between the CSI scores, site of pain, and QOL.

RESULTS

The prevalence of low back pain was the highest (67.6%). The average CSI score was 14.2 points; 8% of volunteers had a high (> 30) CSI score. The CSI scores among women were significantly higher than those among men (p = .016). The CSI scores had a significantly moderate correlation with the numerical rating scale and QOL scores (all p < .001). Volunteers with neck pain showed the highest CSI scores (average 22.4 points).

CONCLUSIONS

The CSI total score showed sex differences and had a significant correlation with pain severity and QOL.

STUDY DESIGN

Cross-sectional study.

Comorbidity of Fibromyalgia in Primary Knee Osteoarthritis: Potential Impact on Functional Status and Quality of Life

BACKGROUND

Knee osteoarthritis (OA) is a painful condition with peripheral and central pain transmission. Fibromyalgia (FM) is the role model of central sensitization of pain perception.

AIM

To assess the frequency of FM in knee OA patients and evaluate the impact of FM on mental health and the quality of life in knee OA patients.

PATIENTS AND METHODS

A total of 121 female patients were recruited and divided into 3 groups: group I of 59 patients with knee OA only, group II of 32 patients with knee OA and FM, and group III of 30 FM patients. Patients underwent history taking, examination, investigations, and radiological evaluation of both knees. The assessment of visual analog scale (VAS), Pittsburgh Sleep Quality Index (PSQI), Pain Anxiety Symptom Scale Short Form 20 (PASS20), Beck Depression Inventory (BDI-II), and PCASEE questionnaire were done for all patients. Lequesne index of knee OA and radiological Kellgren and Lawrence score severity were done for all OA patients. Fibromyalgia Impact Questionnaire (FIQ) was assessed for all FM patients.

RESULTS

FM was diagnosed in 35.5% of knee OA patients. Group II patients had higher VAS, PASS-20, PSQI, and lower quality of life than either groups I and III, elevated Lequesne index score than group I, significant correlation between VAS and BMI (p=0.002), Lequesne index score (p<0.001), PASS20 (p=0.006), BDI-II score (p=0.002), and FIQ (P<0.001), and a negative correlation was found between VAS and physical (p<0.001), anxiety (p=0.046), and social (p=0.026) QoL parameters. Univariable regression analysis showed a higher age, VAS, PSQI, PASS20, and FIQ were associated with lower QoL in group II. A higher PASS20 was the only predictor of lower QoL in multivariable analysis.

CONCLUSION

Fibromyalgia coexists frequently in knee OA patients and has implications on their mental health, functional activity, and quality of life.

The Association Between Alcohol Consumption and Pain Interference in a Nationally Representative Sample: The Moderating Roles of Gender and Alcohol Use Disorder Symptomatology

BACKGROUND

Prior research on alcohol consumption and pain has yielded inconsistent results regarding the directionality of effects for both consumption-to-pain and pain-to-consumption relations. The present study sought to examine directionality of these relations by testing bidirectional longitudinal associations between consumption and pain interference, a crucial aspect of pain that captures pain-related disability and has been regarded as a valuable measure of treatment outcome. In addition, this study explored possible moderation of these bidirectional longitudinal associations by gender and alcohol use disorder (AUD) symptomatology.

METHODS

Analyses included 29,989 current/former drinkers who were interviewed at both waves (2001 and 2004) of the U.S. National Epidemiological Survey on Alcohol and Related Conditions (NESARC). Analyses used self-report data from both waves on past-year average daily volume of alcohol consumed and past-month pain interference (1 item from the Medical Outcomes Study 12-item Short-Form Health Survey [MOS-SF-12]). AUDADIS-IV data from Wave 1 were used to index baseline AUD symptomatology (i.e., symptom count). Cross-lagged panel modeling and multigroup analyses were employed.

RESULTS

Regarding the consumption-to-pain-interference relation, in general, higher baseline alcohol consumption was associated with lower subsequent pain interference at follow-up. However, among men with higher AUD-symptom counts, the opposite pattern emerged, with higher baseline alcohol consumption being significantly related to higher subsequent pain interference at follow-up. Regarding the pain-interference-to-consumption relation, higher baseline pain interference was significantly associated with lower subsequent alcohol consumption at follow-up, and no moderating effects were observed.

CONCLUSIONS

The distinctive patterns of the consumption-to-pain-interference relation observed among men with elevated AUD symptomatology suggest that this relation might be driven by different mechanisms across different groups of individuals. Specifically, the detrimental effect of alcohol on pain interference might emerge at relatively advanced stages of AUD among men, consistent with Koob's Dark Side of Alcohol Addiction theory in human research.