The Relationship Between Clinical and Quantitative Measures of Pain Sensitization in Knee Osteoarthritis

Activity-related pain and sensitization predict within- and between-person pain experience in people with knee osteoarthritis: An ecological momentary assessment study

Background and objectives

Knee Osteoarthritis (OA) is a prevalent musculoskeletal condition that often results in pain and disability. Determining factors predicting variability in pain experience is critical to improving clinical outcomes. Underlying pain sensitization and its clinical manifestations, such as activity-related pain, may better predict the knee OA pain experience. This study aimed to determine whether Quantitative Sensory Testing (QST) derived sensitization measures and activity-related pain predict knee OA pain experiences collected via smartphone ecological momentary assessment (EMA).

Design

Individuals with knee OA were recruited from an urban community in New Zealand. Those eligible to participate underwent baseline QST with clinical measures of activity-related pain also being collected. The knee OA pain experience was collected via smartphone EMA three times daily for two weeks. Mixed effects location scale models were developed using a multilevel modelling approach.

Results

Eighty-six participants with knee OA participated in the study. Mean age was 67.3 years, with most of the participants being female (64%) and New Zealand European (90.6%). Activity-related pain predicted worse and more variable pain intensity, pain interference, and bothersomeness outcomes within and between individuals with knee OA. Widespread cold hyperalgesia and local mechanical hyperalgesia were shown to predict higher within-person variability in pain intensity and pain interference respectively, while mechanical temporal summation predicted less within-person variability in pain intensity and interference.

Discussion

Those demonstrating activity-related pain and sensitization could be at risk of experiencing worse and more variable knee OA pain in the subsequent weeks. Testing for sensitization in clinical practice could therefore identify those at greatest risk of higher and more variable knee OA pain experiences and in greatest need of treatment. Larger validation studies are required, which include individuals with more severe knee OA.

Fatty acid binding protein 5 inhibition attenuates pronociceptive cytokine/chemokine expression and suppresses osteoarthritis pain: A comparative human and rat study

OBJECTIVE

Osteoarthritis (OA) is often accompanied by debilitating pain that is refractory to available analgesics due in part to the complexity of signaling molecules that drive OA pain and our inability to target these in parallel. Fatty acid binding protein 5 (FABP5) is a lipid chaperone that regulates inflammatory pain; however, its contribution to OA pain has not been characterized.

DESIGN

This combined clinical and pre-clinical study utilized synovial tissues obtained from subjects with end-stage OA and rats with monoiodoacetate-induced OA. Cytokine and chemokine release from human synovia incubated with a selective FABP5 inhibitor was profiled with cytokine arrays and ELISA. Immunohistochemical analyses were conducted for FABP5 in human and rat synovium. The efficacy of FABP5 inhibitors on pain was assessed in OA rats using incapacitance as an outcome. RNA-seq was then performed to characterize the transcriptomic landscape of synovial gene expression in OA rats treated with FABP5 inhibitor or vehicle.

RESULTS

FABP5 was expressed in human synovium and FABP5 inhibition reduced the secretion of pronociceptive cytokines (interleukin-6 [IL6], IL8) and chemokines (CCL2, CXCL1). In rats, FABP5 was upregulated in the OA synovium and its inhibition alleviated incapacitance. The transcriptome of the rat OA synovium exhibited >6000 differentially expressed genes, including the upregulation of numerous pronociceptive cytokines and chemokines. FABP5 inhibition blunted the upregulation of the majority of these pronociceptive mediators.

CONCLUSIONS

FABP5 is expressed in the OA synovium and its inhibition suppresses pronociceptive signaling and pain, indicating that FABP5 inhibitors may constitute a novel class of analgesics to treat OA.

Effectiveness of pain neuroscience education on somatosensory functioning after surgery for breast cancer: A double-blinded randomized controlled trial

Pain is one of the most prevalent and long-term adverse effects described by people who have undergone breast cancer surgery. Non-helpful perceptions and thoughts about pain may contribute to the transition of acute to persistent pain. Adding educational interventions to the current physical therapy program in this population may help to improve or prevent persistent pain. Pain neuroscience education (PNE) is a type of educational intervention that addresses the experience of pain in a broader sense by explaining pain not only from a biomedical perspective, but also from a psychological and social perspective. A double-blinded randomized controlled trial (EduCan trial) investigated whether PNE, in addition to a standard physiotherapy program immediately after surgery for breast cancer, was more effective on somatosensory functioning in the short (4 months postoperatively) and long term (18 months postoperatively), than providing a biomedical explanation for pain. Somatosensory functioning was evaluated using a self-reported questionnaire as well as a comprehensive quantitative sensory testing evaluation. The findings of this study revealed that adding six sessions of PNE to a standard physical therapy program (n = 184) did not result in a significantly different course of somatosensory functioning up to 18 months postoperatively as compared to biomedical pain education. These findings provide an interesting basis for future research into who should receive PNE after surgery for breast cancer (e.g., patient profiling or phenotyping) and how we can tailor it to the individual to increase its effectiveness.

A Secondary Analysis: Comparison of Experimental Pain and Psychological Impact in Individuals with Carpometacarpal and Knee Osteoarthritis

Purpose

Evaluate sensory and psychological differences in individuals with thumb carpometacarpal (CMC) and/or knee osteoarthritis (OA) pain. This secondary analysis focuses on comparing the effects of OA at large and small joints in community-dwelling adults.

Patients and Methods

A total of 434 individuals were recruited from communities in Gainesville, FL and Birmingham, AL. Each participant completed health and clinical history questionnaires, quantitative sensory testing, and physical functional tests. Participants were divided into four groups based on their pain ("CMC pain" (n = 33), "knee pain" (n = 71), "CMC + knee pain" (n = 81), and "pain-free" controls (n = 60)). ANCOVAs were performed to identify significant differences in experimental pain and psychological variables across groups.

Results

The "CMC + knee pain" group had lower pressure pain thresholds (lateral knee site, p < 0.01) and higher temporal summation of mechanical pain (knee, p < 0.01) when compared to "CMC pain" and "pain-free" groups. The "knee pain" group had lower heat pain tolerance at the forearm site (p = 0.02) and higher mechanical pain (p < 0.01) at both tested sites in comparison to the "CMC pain" group. Lastly, the "CMC + knee pain" group had the highest self-reported pain (p < 0.01) and disability (p < 0.01) compared to all other groups.

Conclusion

Results suggest knee OA compounded with CMC OA increases disease impact and decreases emotional health compared to OA at either the CMC or knee joint alone. Results also support a relationship between the number of painful joints and enhanced widespread pain sensitivity. Measuring pain at sites other than the primary OA location is important and could contribute to more holistic treatment and prevention of OA progression.

Frequency of multisite non-hand joint involvement in patients with thumb-base osteoarthritis, and associations with functional and patient-reported outcomes

Purpose

In OA studies, the focus often is on an index-joint; other affected joint sites are often overlooked. In this thumb-base OA study, we documented the frequency of symptomatic non-hand joint sites and investigated whether their count was associated with thumb-specific functional and patient-reported outcome measures.

Design

Patients seeking care for thumb-base OA (conservative or surgical) were included. A patient-completed questionnaire captured sociodemographic and health characteristics, symptomatic hand and non-hand joint sites, and outcome measures (thumb-base pain intensity, symptoms and disability (TASD) and upper-extremity disability/symptoms (quickDASH)). Grip and pinch strength were measured. Linear regressions examined the association between each outcome and symptomatic joint site count, adjusted for several covariates.

Results

The mean age of the 145 patients was 62 years, 72% were female. Mean symptomatic non-hand joint site count was 3.6. Ten percent reported only their hands as symptomatic; 30% reported 2-3 other symptomatic sites, and 49% reported 4+. From cross-sectional multivariable analyses, a higher symptomatic non-hand joint site count was associated with worse scores for all patient-reported outcomes and grip strength. Every unit increase in joint site count (49% had a 4+ count) was associated with a 2.1-3.3 unit increase (worse) in patient-reported outcome scores (all p ​< ​0.02).

Conclusions

In this sample, nearly 80% of patients had 2+ symptomatic non-hand joint sites. These symptoms were associated with worse thumb- and hand-specific outcomes, suggesting a need for awareness of whole body OA burden, with implications for outcome score interpretations, study designs, and provision of care in thumb-base OA.

Comprehensive quantitative sensory testing shows altered sensory function in women with chronic pelvic pain: results from the Translational Research in Pelvic Pain (TRiPP) Study

ABSTRACT

Chronic pelvic pain (CPP), despite its high prevalence, is still relatively poorly understood mechanistically. This study, as part of the Translational Research in Pelvic Pain (TRiPP) project, has used a full quantitative sensory testing (QST) paradigm to profile n = 85 women with and without CPP (endometriosis or bladder pain specifically). We used the foot as a control site and abdomen as the test site. Across 5 diagnostically determined subgroups, we found features which are common across different aetiologies, eg, gain of function in pressure pain threshold (PPT) when assessing responses from the lower abdomen or pelvis (referred pain site). However, disease-specific phenotypes were also identified, eg, greater mechanical allodynia in endometriosis, despite there being large heterogeneities within diagnostic groups. The most common QST sensory phenotype was mechanical hyperalgesia (>50% across all the groups). A "healthy' sensory phenotype was seen in <7% of CPP participants. Specific QST measures correlated with sensory symptoms assessed by the painDETECT questionnaire (pressure-evoked pain [painDETECT] and PPT [QST] [ r = 0.47, P < 0.001]; mechanical hyperalgesia (painDETECT) and mechanical pain sensitivity [MPS from QST] [ r = 0.38, P = 0.009]). The data suggest that participants with CPP are sensitive to both deep tissue and cutaneous inputs, suggesting that central mechanisms may be important in this cohort. We also see phenotypes such as thermal hyperalgesia, which may be the result of peripheral mechanisms, such as irritable nociceptors. This highlights the importance of stratifying patients into clinically meaningful phenotypes, which may have implications for the development of better therapeutic strategies for CPP.

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.

Post-surgical contributors to persistent knee pain following knee replacement: The Multicenter Osteoarthritis Study (MOST)

Objective

Pain persistence following knee replacement (KR) occurs in ∼20-30% of patients. Although several studies have identified preoperative risk factors for persistent post-KR pain, few have focused on post-KR contributing factors. We sought to determine whether altered nociceptive signaling and other peripheral nociceptive drivers present post-operatively contribute to post-KR pain.

Design

We included participants from the Multicenter Osteoarthritis Study who were evaluated ∼12 months after KR. We evaluated the relation of measures of pain sensitivity [pressure pain threshold (PPT), temporal summation (TS), and conditioned pain modulation (CPM)] and the number of painful body sites to post-KR WOMAC knee pain, and of the number of painful sites to altered nociceptive signaling using linear or logistic regression models, as appropriate.

Results

171 participants (mean age 69 years, 62% female) were included. TS was associated with worse WOMAC pain post-KR (β ​= ​0.77 95% CI:0.19-1.35) and reduced odds of achieving patient acceptable symptom state (aOR ​= ​0.54 95%CI:0.34-0.88). Inefficient CPM was also associated with worse WOMAC pain post-KR (β ​= ​1.43 95% CI:0.15-2.71). In contrast, PPT was not associated with these outcomes. The number of painful body sites present post-KR was associated with TS (β ​= ​0.05, 95% CI:0.01, 0.05).

Conclusions

Post-KR presence of central sensitization and inefficient descending pain modulation was associated with post-KR pain. We also noted that presence of other painful body sites contributes to altered nociceptive signaling, and this may thus also contribute to the experience of knee pain post-KR. Our findings provide novel insights into central pain mechanisms and other peripheral pain sources contributing to post-KR persistent knee pain.

Correlation of Fibromyalgia Survey Questionnaire and Quantitative Sensory Testing Among Patients With Active Rheumatoid Arthritis

OBJECTIVE

Patients with rheumatoid arthritis (RA) commonly demonstrate disordered pain processing associated with high pain sensitization. Pain sensitization is often assessed using quantitative sensory testing (QST), which is burdensome to patients. The self-administered Fibromyalgia Survey Questionnaire (FSQ) has been proposed as a low-burden, surrogate measure of central pain sensitization. We examined the correlation between FSQ and QST in patients with active RA.

METHODS

Participants in the Central Pain in Rheumatoid Arthritis (CPIRA) cohort underwent FSQ and QST evaluation at enrollment. QST measures included pressure pain threshold (PPT) at the thumb, trapezius, wrist, and knee; temporal summation (TS) at the wrist and arm; and conditioned pain modulation (CPM). Partial Spearman correlation between FSQ and each QST measure was assessed, adjusted for demographic factors, study site, disease characteristics, and pain catastrophizing. Sensitivity analyses included (1) stratified analysis by sex and (2) evaluation of how each component of FSQ associates with the QST measures.

RESULTS

Among 285 participants with active RA, FSQ was weakly but statistically significantly correlated with PPT (r range = -0.31 to -0.21), and TS (r range = 0.13-0.15) at all sites in unadjusted analyses. After adjustment, statistically significant correlations persisted for TS at the wrist and PPT at all sites (except the thumb). Sensitivity analyses did not identify differences in association based on sex or with individual FSQ components.

CONCLUSION

FSQ and QST were correlated among participants with active RA, but the strength of association was weak. QST and FSQ are not interchangeable measures of pain sensitization.

Personal influencing factors for pressure pain threshold in healthy people: A systematic review and meta-analysis

All studies that investigated personal factors influencing pressure pain threshold (PPT) in healthy people were synthesized. Data was summarized, and risk of bias (RoB) and level of evidence were determined. Results were pooled per influencing factor, grouped by body region and included in meta-analyses. Fifty-four studies were eligible. Five had low, nine moderate, and 40 high RoB. Following meta-analyses, a strong conclusion was found for the influence of scapular position, a moderate for the influence of gender, and a weak for the influence of age (shoulder/arm region) and blood pressure on PPT. In addition, body mass index, gender (leg region), alcohol consumption and pain vigilance may not influence PPT. Based on qualitative summary, depression and menopause may not influence PPT. For other variables there was only preliminary or conflicting evidence. However, caution is advised, since the majority of included studies showed a high RoB and several were not eligible to include in meta-analyses. Heterogeneity was high in the performed meta-analyses, and most conclusions were weak. More standardized research is necessary.

Questionnaire-based somatosensory profiling in breast cancer survivors: are we there yet? Associations between questionnaires and quantitative sensory testing

PURPOSE

Pain and sensory disturbances are common side effects of breast cancer treatment. Differential somatosensory functioning may reflect distinct pathophysiological backgrounds and therapeutic needs. Aim was to examine whether questionnaires evaluating signs and symptoms related to somatosensory functioning correlate sufficiently with quantitative sensory testing (QST) in breast cancer survivors to warrant consideration for somatosensory profiling in clinical practice.

METHODS

One year after breast cancer surgery, 147 women underwent QST and completed following questionnaires: Douleur Neuropathique en 4 questions (DN4), Central Sensitization Inventory, Margolis Pain Diagram and Visual Analog Scales (VAS). Associations between the questionnaires and QST were evaluated using Spearman correlation coefficients (rs).

RESULTS

Significant but weak (rs < 0.30) correlations were found between total DN4 score and QST results at the inner upper arm for detection of sharp stimuli (rs = 0.227), cold stimuli (rs = -0.186), and painful heat stimuli (rs = 0.179), as well as between QST evaluating conditioned pain modulation and the Margolis Pain Diagram on one hand (rs = 0.176) and minimum-maximum pain intensity differences (VAS) on the other (rs = -0.170).

CONCLUSION

Questionnaires evaluating signs and symptoms related to somatosensory functioning are insufficient for somatosensory profiling. Although somatosensory profiling may be valuable in a mechanism-based management, more research on the most appropriate clinical tools is needed.IMPLICATIONS FOR REHABILITATIONClinicians should be able to recognize that patients with persistent pain or sensory disturbances following breast cancer surgery may have a component of altered somatosensory processing as a significant contributor to their complaint in order to address it appropriately.Somatosensory profiling has yet to be implemented into clinical practice.No evidence-based recommendations can be made on the use of self-reported questionnaires to assess somatosensory processing in a breast cancer population based on the findings of this study.It is suggested to combine information on how individuals process and experience somatosensory stimulation with information from the patient interview or questionnaires to consider which biological, psychological and/or social factors may drive or sustain these neurophysiological processes.

Detection of altered pain facilitatory and inhibitory mechanisms in patients with knee osteoarthritis by using a simple bedside tool kit (QuantiPain)

Supplemental Digital Content is Available in the Text.

A simple bedside quantitative sensory testing tool kit demonstrated acceptable reliability and assessment validity for detecting altered pain facilitatory and inhibitory mechanisms in patients with painful osteoarthritis.

Purpose:

Altered pain facilitatory and inhibitory mechanisms have been recognized as an important manifestation in patients with chronic pain, and quantitative sensory testing (QST) can act as a proxy for this process. We have recently developed a simple bedside QST tool kit (QuantiPain) for more clinical use. The purpose of this study was to investigate its test–retest reliability and to evaluate its validity compared with the laboratory-based QST protocols in patients with knee osteoarthritis (OA).

Methods:

QuantiPain consists of 3 items: “pressure algometer” (for pressure pain thresholds [PPTs]), “pinprick” (for temporal summation of pain [TSP]), and “conditioning clamp” (for conditioned pain modulation [CPM]). In experiment-A, intrarater and interrater test–retest reliabilities were investigated in 21 young healthy subjects by using interclass correlation coefficient (ICC). In experiment-B, 40 unilateral painful patients with OA and 40 age-matched, healthy control subjects were included to compare the bedside tool kit against the computerized pressure algometry.

Results:

In experiment-A, excellent to moderate intrarater and interrater reliabilities were achieved in PPT and TSP (ICC: 0.60–0.92) while the agreements of CPM were good to poor (ICC: 0.37–0.80). In experiment-B, localized and widespread decrease of PPT, facilitated TSP, and impaired CPM was found by using the bedside tool kit in patients with OA compared with controls (P < 0.05). The data were significantly correlated with the established laboratory-based tools (R = 0.281–0.848, P < 0.05).

Conclusion:

QuantiPain demonstrated acceptable test–retest reliability and assessment validity with the sensitivity to separate patients with painful OA from controls, which has a potential to create more practical approach for quantifying altered pain mechanisms in clinical settings.

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.

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

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

Associations of pain sensitisation with tender and painful joint counts in people with hand osteoarthritis: results from the Nor-Hand study

Objective

To examine associations of pain sensitisation with tender and painful joint counts and presence of widespread pain in people with hand osteoarthritis (OA).

Methods

Pressure pain thresholds (PPT) at a painful finger joint and the tibialis anterior muscle, and temporal summation (TS) were measured in 291 persons with hand OA. We examined whether sex-standardised PPT and TS values were associated with assessor-reported tender hand joint count, self-reported painful hand and total body joint counts and presence of widespread pain using linear and logistic regression analyses adjusted for age, sex, body mass index, education and OA severity.

Results

People with lower PPTs at the painful finger joint (measure of peripheral and/or central sensitisation) had more tender and painful hand joints than people with higher PPTs. PPT at tibialis anterior (measure of central sensitisation) was associated with painful total body joint count (beta=−0.82, 95% CI −1.28 to –0.35) and presence of widespread pain (OR=0.57, 95% CI 0.43 to 0.77). The associations between TS (measure of central sensitisation) and joint counts in the hands and the total body were statistically non-significant.

Conclusion

This cross-sectional study suggested that pain sensitisation (ie, lower PPTs) was associated with joint counts and widespread pain in hand OA. This knowledge may be used for improved pain phenotyping of people with hand OA, which may contribute to better pain management through more personalised medicine. Further studies are needed to assess whether a reduction of pain sensitisation leads to a decrease in tender and painful joint counts.

No added value of duloxetine for patients with chronic pain due to hip or knee osteoarthritis: a cluster randomised trial

Objective

To assess the effectiveness of duloxetine in addition to usual care in patients with chronic osteoarthritis (OA) pain. The cost‐effectiveness and whether the presence of symptoms of centralized pain alters the response to duloxetine were secondary objectives.

Methods

We conducted an open‐label, cluster‐randomized trial. Patients with chronic hip or knee OA pain who had an insufficient response to acetaminophen and nonsteroidal antiinflammatory drugs were included. Randomization took place at the general practice level, and patients received duloxetine (60 mg/day) in addition to usual care or usual care alone. The presence of centralized pain was defined as a modified PainDETECT Questionnaire score >12. The primary outcome measure was Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores (scale 0–20) at 3 months after the initiation of treatment. Our aim was to detect a difference between the groups of a clinically relevant effect of 1.9 points (effect size 0.4). We used a linear mixed model with repeated measurements to analyze the data.

Results

In total, 133 patients were included, and 132 patients were randomized into treatment groups. A total of 66 patients (at 31 practices) were randomized to receive duloxetine in addition to usual care, and 66 patients (at 35 practices) were randomized to receive usual care alone. We found no differences in WOMAC pain scores between the groups at 3 months (adjusted difference –0.58 [95% confidence interval (95% CI) –1.80, 0.63]) or at 12 months (adjusted difference –0.26 [95% CI –1.86, 1.34]). In the subgroup of patients with centralized pain symptoms, we also found no effect of duloxetine compared to usual care alone (adjusted difference –0.32 [95% CI –2.32, 1.67]).

Conclusion

We found no effect of duloxetine added to usual care compared to usual care alone in patients with chronic knee or hip OA pain. Another trial including patients with centralized pain symptoms should be conducted to validate our results.

Quantitative Sensory Testing Protocols to Evaluate Central and Peripheral Sensitization in Knee OA: A Scoping Review

OBJECTIVE

This scoping review analyzed various quantitative sensory testing methodologies used in the assessment of sensitization and how sensitization is defined in people with knee osteoarthritis.

DESIGN

A scoping review.

SETTING

All clinical and research settings.

SUBJECTS

Non-surgical adults with knee osteoarthritis.

METHODS

This scoping review was guided by existing scoping review methodologies. Relevant studies were extracted from the following electronic databases: Medical Literature Analysis and Retrieval System Online, Excerpta Medica Database, Allied and Complementary Medicine Database and the Cumulative Index to Nursing Allied Health Literature. Abstract and full article screening and data extraction were performed in pairs. Information on quantitative sensory testing techniques and parameters was extracted and summarized in tables. General and technique specific definitions of sensitization were extracted from included texts.

RESULTS

Our search yielded 4199 articles, of which 50 were included in our review. The most common quantitative sensory test was pressure pain threshold. In total 28 unique testing sites were found speaking to the high degree of variability between studies. Sensitization was poorly defined with only 8 studies fully operationalizing it, 22 partially, and the remainder did not provide sufficient information to meet our criteria.

CONCLUSION

This scoping review has provided an overview of the most common methods of quantitative sensory testing being implemented in the assessment of nervous system sensitization to nociceptive signaling in people with knee osteoarthritis. This study provides a foundation for future development of quantitative sensory testing methodology for research and clinical practice in the osteoarthritis population.

Assessment of Central Sensitization in Breast Cancer Survivors: Convergent Validity and Use of the Central Sensitization Inventory (CSI) and Its Short-Form as a Clustering Tool

The Central Sensitization Inventory (CSI) measurement properties in patients having nonspecific, noncancer pain are well-established. However, studies examining the reliability and validity of either the CSI or the Central Sensitization Inventory short-form version (CSI-9) in breast cancer survivors (BCS) are scarce. The purpose was to evaluate convergent validity and internal consistency of the CSI and CSI-9. Additionally, the relevance of a new cluster calculator using the CSI was explored. The cross-sectional multi-center study included 65 BCS and 37 healthy volunteers. Patients filled out multiple questionnaires assessing pain, number of painful areas, anxiety, depression and quality of life. The relevance of a cluster calculator was explored by known-group comparisons and boxplot description. All hypotheses were formulated before data analysis. The majority of hypotheses on the correlations between the CSI or CSI-9 and other health outcomes were confirmed (22 out of 27). The CSI and CSI-9 have excellent (α = 0.92) and good (α = 0.86) internal consistency, respectively. The CSI cluster calculator might be an interesting tool to use to have a patient's overall condition snapshot. Generally, the study findings support the construct validity and internal consistency of the CSI, which underline the use of this self-reported instrument in BCS. The CSI-9 shows promising results, but should be further evaluated.

Systematic review and meta-analysis of the prevalence of neuropathic-like pain and/or pain sensitization in people with knee and hip osteoarthritis

OBJECTIVE

To determine the prevalence of neuropathic-like pain (NP) and pain sensitization (PS) defined by self-report questionnaires in knee and hip osteoarthritis, and whether prevalence is potentially explained by disease-severity or affected joint.

DESIGN

MEDLINE, EMBASE, CINAHL were systematically searched (1990-April 2020) for studies describing the prevalence of NP and PS in knee and hip osteoarthritis using self-report questionnaires. Random-effects meta-analysis was performed. Statistical heterogeneity between studies and sub-groups (affected joint and population source as a proxy for disease severity) was assessed (I² statistic and the Chi-squared test).

RESULTS

From 2,706 non-duplicated references, 39 studies were included (2011-2020). Thirty-six studies reported on knee pain and six on hip pain. For knee osteoarthritis, the pooled prevalence of NP was: using PainDETECT, possible NP(score ≥13) 40% (95%CI 32-48%); probable NP(score >18) 20% (95%CI 15-24%); using Self-Report Leeds Assessment of Neuropathic Symptoms and Signs, 32% (95%CI 26-38%); using Douleur Neuropathique (DN4) 41% (95% CI 24-59%). The prevalence of PS using Central Sensitization Inventory (CSI) was 36% (95% CI 12-59%). For hip osteoarthritis, the pooled prevalence of NP was: using PainDETECT, possible NP 29% (95%CI 22-37%%); probable NP 9% (95%CI 6-13%); using DN4 22% (95%CI 12-31%) in one study. The prevalence of possible NP pain was higher at the knee (40%) than the hip (29%) (difference 11% (95% CI 0-22%), P = 0.05).

CONCLUSIONS

Using self-report questionnaire tools, NP was more prevalent in knee than hip osteoarthritis. The prevalence of NP in knee and hip osteoarthritis were similar for each joint regardless of study population source or tool used. Whether defining NP using self-report questionnaires enables more effective targeted therapy in osteoarthritis requires investigation.

Disability, burden, and symptoms related to sensitization in migraine patients associate with headache frequency

OBJECTIVES

This observational study aimed to assess the difference in disability, burden, and sensitization between migraine patients with low-frequency headache attack (1-8 headache days/month), high-frequency headache attack (9-14 headache days/months), and patients with chronic migraine (>14 headache days/months).

METHODS

Migraine patients with or without aura were divided into three groups according to headache frequency (low-frequency episodic migraine; high-frequency episodic migraine; chronic migraine). Questionnaires were used to assess the burden of headache, quality of life, phycological burden, and symptoms related to sensitization (estimated by the Central Sensitization Inventory). Differences among migraine groups were assessed using Chi-Quadro test, ANOVA, or Kruskal-Wallis as appropriate.

RESULTS

136 patients were included (68 low-frequency episodic migraine, 45 high-frequency episodic migraine, 23 chronic migraine). Patients with high frequency episodic migraine and chronic migraine differed from patients with low frequency episodic migraine showing a worse burden of headache (p=0.002; p=0.002), worse level of physical (p=0.001; p<0.001) and mental (p=0.002; p=0.001) quality of life, worse level of depression (p=0.008; p=0.003), and increase presence of symptoms related to sensitization (p<0.001; p=0.003). No differences were found in any variables between patients with high-frequency episodic migraine and patients with chronic migraine (p>0.05).

CONCLUSIONS

Patients with high-frequency episodic migraine and chronic migraine could be considered in the same segment of the migraine population, with similar degrees of disability and sensitization related symptoms.

[Pain evolution in patients with central sensitization and osteoarthritis after knee arthroplasty]

INTRODUCTION

In patients with knee osteoarthritis, a group of 30% has been identified with central pain sensitization (CPS). The aim is to analyze the persistence of CPS in patients after knee arthroplasty and its correlation with pain intensity, functionality, determining factors and to evaluate physical examination as an assessment instrument.

MATERIAL AND METHODS

Quasi-experimental before-after study of patients operated on total knee arthroplasty. The evolution of subjective variables (pain characteristics, painDETECT questionnaire, WOMAC and Numerical Rating Scale) and physical examination (thermal hyperalgesia, allodynia, hypoesthesia, algometry and goniometry) 3 months before and 3 and 6 months after surgery are analysed using repeated measures ANOVA test for the quantitative ones and Cochran's Q for the qualitative ones. Spearmen test was used for the correlation of the questionnaires, the PD-Q and exploration variables and for the multivariate model of the PD-Q with clinical determinants.

RESULTS

Sixty-seven patients completed the study. The evolution of the quantitative and qualitative variables was significant, with a correlation between questionnaires. In the linear multivariate model of PD-Q, a significant relationship was obtained from personal history of flexion limitation, chronic musculoskeletal pain and the association between depression and time.

CONCLUSIONS

A significant percentage of patients with knee osteoarthritis after arthroplasty persisted with probable CPS, correlating with intensity and functionality. The limitation of mobility and previous chronic comorbidity could be determinants of CPS, with anamnesis and exploration being useful tools in consultation.

European* clinical practice recommendations on opioids for chronic noncancer pain - Part 1: Role of opioids in the management of chronic noncancer pain

BACKGROUND

Opioid use for chronic non-cancer pain (CNCP) is complex. In the absence of pan-European guidance on this issue, a position paper was commissioned by the European Pain Federation (EFIC).

METHODS

The clinical practice recommendations were developed by eight scientific societies and one patient self-help organization under the coordination of EFIC. A systematic literature search in MEDLINE (up until January 2020) was performed. Two categories of guidance are given: Evidence-based recommendations (supported by evidence from systematic reviews of randomized controlled trials or of observational studies) and Good Clinical Practice (GCP) statements (supported either by indirect evidence or by case-series, case-control studies and clinical experience). The GRADE system was applied to move from evidence to recommendations. The recommendations and GCP statements were developed by a multiprofessional task force (including nursing, service users, physicians, physiotherapy and psychology) and formal multistep procedures to reach a set of consensus recommendations. The clinical practice recommendations were reviewed by five external reviewers from North America and Europe and were also posted for public comment.

RESULTS

The key clinical practice recommendations suggest: (a) first optimizing established non-pharmacological treatments and non-opioid analgesics and (b) considering opioid treatment if established non-pharmacological treatments or non-opioid analgesics are not effective and/or not tolerated and/or contraindicated. Evidence- and clinical consensus-based potential indications and contraindications for opioid treatment are presented. Eighteen GCP recommendations give guidance regarding clinical evaluation, as well as opioid treatment assessment, monitoring, continuation and discontinuation.

CONCLUSIONS

Opioids remain a treatment option for some selected patients with CNCP under careful surveillance.

SIGNIFICANCE

In chronic pain, opioids are neither a universal cure nor a universally dangerous weapon. They should only be used for some selected chronic noncancer pain syndromes if established non-pharmacological and pharmacological treatment options have failed in supervised pain patients as part of a comprehensive, multi-modal, multi-disciplinary approach to treatment. In this context alone, opioid therapy can be a useful tool in achieving and maintaining an optimal level of pain control in some patients.

Central sensitisation in chronic pain conditions: latest discoveries and their potential for precision medicine

Chronic pain is a leading cause of disability globally and associated with enormous health-care costs. The discrepancy between the extent of tissue damage and the magnitude of pain, disability, and associated symptoms represents a diagnostic challenge for rheumatology specialists. Central sensitisation, defined as an amplification of neural signalling within the CNS that elicits pain hypersensitivity, has been investigated as a reason for this discrepancy. Features of central sensitisation have been documented in various pain conditions common in rheumatology practice, including fibromyalgia, osteoarthritis, rheumatoid arthritis, Ehlers-Danlos syndrome, upper extremity tendinopathies, headache, and spinal pain. Within individual pain conditions, there is substantial variation among patients in terms of presence and magnitude of central sensitisation, stressing the importance of individual assessment. Central sensitisation predicts poor treatment outcomes in multiple patient populations. The available evidence supports various pharmacological and non-pharmacological strategies to reduce central sensitisation and to improve patient outcomes in several conditions commonly seen in rheumatology practice. These data open up new treatment perspectives, with the possibility for precision pain medicine treatment according to pain phenotyping as a logical next step. With this view, studies suggest the possibility of matching non-pharmacological approaches, or medications, or both to the central sensitisation pain phenotypes.

Comparison of Predisposing Factors Between Pain on Walking and Pain at Rest in Patients with Knee Osteoarthritis

Purpose

Patients with knee osteoarthritis (OA) complain of various types of pain, divided into two main categories: pain on movement and pain at rest. A thorough understanding of pain is essential for managing knee OA; however, few studies have investigated the mechanisms underlying the two different types of pain. This study aimed to clarify the predisposing factors for pain in patients with knee OA with a focus on differences between pain on walking and pain at rest.

Patients and Methods

This study involved 93 patients, aged 44–90 years, with knee OA, including 74 women. We assessed demographic variables (sex, age, body mass index [BMI], side), visual analogue scale (VAS) score on walking, VAS score at rest, Kellgren and Lawrence (KL) grade on radiograph, synovitis score and bone marrow lesion (BML) score on magnetic resonance imaging, and pressure pain threshold (PPT), and used univariate and multiple regression analyses to investigate factors predisposing patients to pain at rest or pain on walking.

Results

In the univariate analyses, we found significant correlations between VAS score on walking and BMI (r=0.31, p<0.01), KL grade (r=0.40, p<0.01), synovitis score (r=0.26, p=0.01), and BML score (r=0.36, p<0.01), whereas VAS score at rest correlated with PPT (r=−0.23, p=0.02) and BMI (r= 0.26, p=0.01). Multiple regression analysis showed that significant explanatory factors for VAS score on walking were BMI (β=0.22, p=0.03) and KL grade (β=0.27, p=0.03). By contrast, PPT was the only significant explanatory factor for VAS score at rest (β=−0.27, p=0.01).

Conclusion

Predisposing factors were significantly different between pain on walking and pain at rest, indicating that different pain mechanisms exist in the two types of pain. Pain on walking was more strongly associated with mechanical and structural factors, while pain at rest was associated with mechanical hyperalgesia of the knee.

Clinical Registration

University Hospital Medical Information Network Clinical Trials Registration number; 000041190.

Update on pain in arthritis

PURPOSE OF REVIEW

Osteoarthritis is a degenerative joint disease that features pain as a hallmark symptom. This review summarises progress and obstacles in our understanding of pain mechanisms in arthritis.

RECENT FINDINGS

Pain phenotypes in osteoarthritis are poorly characterized in clinical studies and animal studies are largely carti-centric. Different animal models incur variable disease progression patterns and activation of distinct pain pathways, but studies reporting both structural and pain outcomes permit better translational insights. In patients, classification of osteoarthritis disease severity is only based on structural integrity of the joint, but pain outcomes do not consistently correlate with joint damage. The complexity of this relationship underlines the need for pain detection in criteria for osteoarthritis classification and patient-reported outcome measures.

SUMMARY

Variable inflammatory and neuropathic components and spatiotemporal evolution underlie the heterogeneity of osteoarthritis pain phenotypes, which must be considered to adequately stratify patients. Revised classification of osteoarthritis at different stages encompassing both structural and pain outcomes would significantly improve detection and diagnosis at both early and late stages of disease. These are necessary advancements in the field that would also improve trial design and provide better understanding of basic mechanisms of disease progression and pain in osteoarthritis.

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.

Lack of correlation between central sensitization inventory and psychophysical measures of central sensitization in individuals with painful temporomandibular disorder

OBJECTIVE

To assess the correlation between the Central Sensitization Inventory (CSI) scores and the results of psychophysical tests and psychosocial questionnaires according to the presence of painful temporomandibular disorder (TMD).

DESIGN

It was a cross-sectional study involving 146 participants, aged 20-65 years. Painful TMD was classified using the Research Diagnostic Criteria for Temporomandibular Disorders. CSI was applied to assess "central sensitization-related symptoms", as has been suggested. Wind-up ratio, pressure pain threshold and conditioned pain modulation were used as psychophysical tests to evaluate signs and symptoms of central sensitization. Psychosocial factors were assessed by the presence of non-specific physical symptoms, depressive and anxiety symptoms. The sample was divided into two groups: Control (n = 31); Painful TMD (n = 115). Descriptive statistics characterized the sample. Correlation analysis were performed using Pearson's and Spearman's correlation coefficients (α = 5%).

RESULTS

Of the total sample, 78.8 % presented painful TMD, and the mean (standard deviation) age was 37.4 (±11.5) years. Anxiety symptoms (p = 0.028) and non-specific physical symptoms (p < 0.001) were more frequent in the painful TMD group than in controls. Painful TMD patients presented higher scores of the CSI (p < 0.001) and lower pressure pain thresholds (p ≤ 0.020) compared to controls. CSI scores were significantly correlated with psychosocial measures (p < 0.001) but not with psychophysical tests (p ≥ 0.089).

CONCLUSION

The CSI scores did not correlate with psychophysical measures of central sensitization but were positively correlated with the results of psychosocial questionnaires.