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Objectives: Despite its impact, individual factors associated with persistent low back pain (LBP) remain poorly understood. This study investigated static and dynamic pain sensitivity in adults with persistent LBP versus pain-free controls; and investigated associations between pain sensitivity and 3 clinical pain measures: recalled, resting, and movement-evoked pain (MEP)., Materials and Methods: A lifespan sample of 60 adults with persistent LBP and 30 age-matched/sex-matched controls completed 4 laboratory sessions. Static pain sensitivity (pressure pain threshold [PPT], heat pain threshold) and dynamic pain sensitivity (heat pain aftersensations [AS], temporal summation [TS] of second heat pain) were measured. Demographic and clinical factors collected were education, global cognition, and perceived health. Resting and recalled pain were measured via questionnaire, and MEP via the Back Performance Scale., Results: LBP participants demonstrated lower PPT remotely (hand; F1,84=5.34, P=0.024) and locally (low back; F1,84=9.55, P=0.003) and also had higher AS (F1,84=6.01, P=0.016). Neither static nor dynamic pain sensitivity were associated with recalled pain (P>0.05). However, static pain sensitivity (local PPT) explained an additional 9% variance in resting pain, while dynamic pain sensitivity (AS, TS) explained an additional 10% to 12% variance in MEP., Discussion: This study characterized pain sensitivity measures among individuals with persistent LBP and suggests static pain sensitivity plays a larger role in resting pain while dynamic pain sensitivity plays a larger role in MEP. Future studies will confirm these relationships and elucidate the extent to which changes in static or dynamic pain sensitivity predict or mediate clinical pain among adults with persistent LBP., Competing Interests: Supported by funding from NIH/NCATS Clinical and Translational Science Awards to the University of Florida (TL1 TR000066, UL1 TR000064), and the University of Florida Department of Physical Therapy, Gainesville, FL. NIH/NIA Award to Duke University (5P30AG0928716), Durham, NC. The authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: The prevalence of knee osteoarthritis (OA) is increasing with the aging population and is exacerbated by the growing numbers of obese older adults. Low levels of vitamin D, measured by serum 25-hydroxyvitamin D (25(OH)D), in older adults and obese individuals are correlated with several negative health conditions, including chronic pain. This cross-sectional study sought to examine the interactive influence of 25(OH)D levels and obesity on knee OA pain and functional performance measures., Methods: The sample consisted of 256 (63% female) racially diverse (55% black/African Americans) middle-aged and older adults (mean age 56.8 y). Blood was collected for analysis of 25(OH)D by high-performance liquid chromatography. Participants provided self-report regarding knee OA pain and underwent a lower extremity functional performance test., Results: Results demonstrated that obesity was associated with lower levels of 25(OH)D. Participants with adequate 25(OH)D levels reported significantly less knee OA pain compared with participants with deficient or insufficient levels, regardless of obesity status. Furthermore, there was a significant interaction between obesity and 25(OH)D levels for lower extremity functional performance, such that obese individuals with adequate 25(OH)D levels demonstrated better performance than those obese participants with deficient or insufficient 25(OH)D levels., Discussion: The mechanisms by which adequate 25(OH)D levels are associated with pain severity and improved function have not been completely elucidated. It may be that the pleiotropic role of biologically active 25(OH)D influences pain and pain processing through peripheral and central mechanisms. Alternatively, higher levels of pain may lead to reduced outdoor activity, which may contribute to both obesity and decreased vitamin D. Thus, investigating vitamin D status in obese and nonobese individuals with knee OA warrants further study.

Objectives: To describe and understand varieties and characteristics of sensitization contributing to hyperalgesia in participants with chronic pain conditions., Methods: Thermal stimulation was delivered to the face, forearm, and calf of pain-free participants and individuals with irritable bowel syndrome, temporomandibular pain disorder (TMD), and fibromyalgia syndrome (FM). Three-second contacts by a preheated thermode occurred at 30-second intervals in ascending and then in descending series (0.7°C steps)., Results: Thermal pain ratings during ascending series were greater at each site in individuals diagnosed with chronic pain. Intense pain at the time of testing further enhanced the ratings at all sites, but mild or moderate clinical pain did not have this effect. Thermal pain in all participants was greater during descending series compared with the ascending series of arm and leg stimulation. The hypersensitivity during the descending series was comparable in pain-free, FM and TMD participants but was increased in duration for arm or leg stimulation of FM participants., Discussion: The widespread sensitization for irritable bowel syndrome and TMD participants does not rely on mechanisms of spatial and temporal summation often invoked to explain widespread hyperalgesia associated with chronic pain. Increased sensitivity during descending series of stimulation of an arm or leg but not the face indicates a propensity for sensitization of nociceptive input to the spinal cord. Abnormally prolonged sensitization for FM participants reveals a unique influence of widespread chronic pain referred to deep somatic tissues.

Sex-correlated differences in pain perception and behavior have been reported in several studies. Where such differences are found, they are most often in the direction of girls and women reporting more pain than is reported by boys and men. Although biologic, psychologic, and sociocultural factors act interdependently to influence pain responding, most efforts to explain sex-correlated differences in pain have focused on first-order biologic differences between the sexes. The current paper discusses empirical and theoretical literature addressing gender role socialization, cognitive factors, and affective factors associated with sex-correlated differences in pain. We affirm that there is convincing evidence that such psychosocial factors must be taken into account in research on sex-correlated differences in pain. We contend that the use of the dichotomous variable sex as a proxy for presumed biologic aspects of being female or male may obscure the contribution to sex-correlated differences that could be ascribed to the ways in which women and men are socialized with respect to pain perception and pain reporting.

Objective: The purpose of this study was to examine the magnitude of the relation between a postmenopausal woman's hormonal replacement status and clinical pain report in a sample of women experiencing orofacial pain., Design: To accomplish this, pain ratings were collected during a routine chronic pain evaluation at an orofacial pain clinic from a sample of 87 postmenopausal women., Results: Results of ANCOVA (controlling for pain duration) demonstrated that postmenopausal women receiving hormone replacement therapy (HRT) reported higher levels of pain than postmenopausal women not taking HRT. Numeric pain rating scales revealed large effect sizes for worst pain report (0.62), moderate differences for average (0.48) and current (0.39) pain levels, and trivial differences for least pain (0.04). Effect sizes for the McGill Pain Questionnaire indicated somewhat smaller differences (0.35-0.24) between the two groups., Conclusions: This study is among the first to examine the relation between a woman's hormonal status and clinical pain perception and is the first to investigate the role of HRT in a postmenopausal woman's orofacial pain report in a clinical treatment setting. This area of inquiry is particularly salient given the high percentage of women who choose to initiate HRT either after hysterectomy or with the onset of menopause.

Objective: The goal of this study was to examine the relative importance of global affective distress, self-report of depressive symptoms, and presence or absence of major depression to the experience of chronic pain., Setting: A multidisciplinary pain program at a university medical center was the setting for this study., Patients: Subjects in this study were 211 consecutive patients with chronic pain., Outcome Measures: Pain duration, compensation, and litigation status were controlled for in the statistical analyses, as each correlated significantly with at least one of the measures of affect. Global affective distress was assessed using the Global Severity Index (GSI) from the Brief Symptom Inventory. The Beck Depression Inventory and the Center for Epidemiological Studies Depression Scale were used as measures of self-report of depressive symptoms. Presence or absence of major depression was based on DSM-IV criteria., Results and Conclusions: The GSI, Beck Depression Inventory, and Center for Epidemiological Studies Depression Scale were significantly correlated with each measure of the experience of pain, although clinical depression was only significantly related to self-reported disability and negative thoughts about pain. The self-report measures of depression maintained their relation to the dependent measures when the somatic items from the scales were removed, suggesting that the relations were not spuriously due to the influence of pain symptoms on the scales. When examining the unique contribution of each variable to the experience of pain (by simultaneously controlling for the other measures of affect), the GSI was uniquely related to the sensory and affective components of pain. Self-report of depressive symptoms was more highly related to a measure of the evaluative component of pain and uniquely related to self-reported disability and negative thoughts about pain. The results are discussed within the context of theoretical models of the relation between pain and affect, and suggestions for future research are presented.

Objective: The purpose of this study was to examine the dimensions of coping, measured by the subscales of the new revised Coping Strategies Questionnaire (CSQ-R) using factor analysis, and to perform cluster analysis on these factors to explore the existence of distinct subgroups. No published studies have identifed subgroups of chronic pain patients based on the use of CSQ coping strategies., Source: A sample of 419 chronic low back pain patients from a multidisciplinary pain rehabilitation clinic and a sample of 556 chronic pain patients of mixed pain etiology presenting for treatment at an anesthesia pain clinic were used to establish reliability of factors and clusters., Results: Both samples yielded very similar two-factor solutions, with initial solutions accounting for 67.1% and 69.1% of the total variance. The factors were characterized as cognitive coping and distraction. Three homogeneous subgroups were then identified that consisted of a group high on cognitive coping, a group with low overall ratings of response CSQ-R items in general, and a group with frequent endorsement of catastrophizing and distraction-related items., Conclusion: This paper is the first to report empirically derived subgroups from scores on the CSQ or CSQ-R. In addition, the three clusters were significantly different across measures of pain, psychological distress, and levels of physical functioning, demonstrating validity for the clusters.

Objective: Although the West Haven-Yale Multidimensional Pain Inventory (MPI) is frequently used in clinical evaluation and research with chronic pain patients, few studies have reported item-level factor analyses. After performing such an analysis, Bernstein et al. (Spine 1995;20:956-63) reported lack of independence between the solicitous and distracting response scales in section II as well as the activities away from home and social activities scales in section III. They suggested that the combination of these scales would improve the internal structure of the MPI. The purpose of this study was to perform a confirmatory factor analysis testing whether the MPI would be improved by the consolidation of these scales. In addition, a third, empirical model was generated for comparison with the West Haven-Yale and Bernstein models., Design: This study used exploratory and confirmatory factor analysis on two independent samples of chronic pain patients (n = 472 and n = 346) to test hypotheses regarding the factor structure of the MPI., Results and Conclusion: Principal axis factor analysis resulted in an empirical model that suggested that the primary psychometric problem of the MPI was lack of item-factor discrimination for several items. When the three models were tested using confirmatory factor analysis, improvement in model fit occurred when cross loading items were excluded. Nevertheless, the goodness of fit of original factor structure was adequate, suggesting it would be premature to suggest changes in this instrument.

Objective: To show clinical utility and empirical validity of Minnesota Multiphasic Personality Inventory-2 (MMPI-2) chronic pain patient subgroups by identification of differential multivariate relationships across groups., Method: This study used structural equation modeling to test cognitive coping strategies and somatization as mediator variables in path models with pain severity and depression used as exogenous (independent) variables and patient's activity level as the final endogenous (dependent) variable, across MMPI-2 profiles., Results: Hierarchical cluster analysis, performed on a sample of 569 chronic low back patients, resulted in four cluster profiles identifiable as those found in previous work with the MMPI-2 (within normal limits, V-type, neurotic triad, and depressed-pathological). Somatization mediated the relationship between depression and activity level for the neurotic triad group but not the other three groups. A positive linear relationship was found between somatization and depression for the within normal limits, neurotic triad, and depressed-pathological groups, whereas their linear association was negative for the V-type group. Cognitive coping strategies mediated the relationship between depression and activity level for the within normal limits group. In addition, cognitive coping was predictive of activity level for the within normal limits, V-type, and neurotic triad groups but not for the depressed-pathological group., Conclusion: Consistent with previous cluster analytic studies, this study replicated four MMPI-2 cluster profile groups in chronic pain patients. These results have also shown that several multivariate relationships between variables are different across MMPI-2 groups, providing evidence for the validity for these MMPI-2 subgroups.

Objective: The Coping Strategies Questionnaire (CSQ), a rationally constructed pain coping assessment instrument, was conceived to measure the extent to which patients used six different cognitive coping strategies and two behavioral coping strategies. A number of studies have factor analyzed the original scales but have not found a reliable factor structure. Recent studies by Turtle et al. and Swartzman et al. have obtained a five-factor solution performing exploratory factor analysis on the individual items. Robinson and associates from the University of Florida performed an item level exploratory factor analysis on a much larger sample (n = 965) and found a six-factor solution that was relatively supportive of the original rationally derived scales. The purpose of the present investigation was to perform a confirmatory factor analysis using the LISREL structural equation modeling program to compare these three different factor structures., Patients: A sample of 472 chronic patients was used., Results and Conclusions: The results indicated that the Florida six-factor model was a better fit to the sample data than either of the five-factor models. Creation of the Coping Strategy Questionnaire Revised (CSQ-R), which retains 27 of the original items, is suggested.

Objective: The Coping Strategies Questionnaire (CSQ), a measure of coping in chronic pain patients, was subjected to item-level exploratory factor analysis., Subjects: A sample of 965 chronic pain patients were used in the analysis., Results: Principal components analysis using a varimax rotation procedure identified nine factors that accounted for 54.5% of the variance. Of these nine factors, the first five represent subscales of the original CSQ subscales. The catastrophizing subscale replicated with significant loadings for all six original items, and ignoring sensations replicated with five of six items. Factors representing reinterpreting pain sensations, coping self-statements, and diverting attention subscales also appeared. The items from the praying and hoping subscale split into separate praying and hoping factors (factors 6 and 8). When reliability coefficients were calculated, factors 7 through 9 had unacceptably low internal consistency and thus were not considered stable factors. Correlations between factors 1 through 6 and other measures of psychological and physical functioning were calculated in the construct validation portion of this study. Previously found relationships were replicated in that the correlations between CSQ factor scores and measures of pain, depression, and disability were in the same direction in this data set as those previously reported.

Objective: Past research has shown response biases to influence the accuracy of results from self-report measures. In pain assessment, where a percentage of patients have financial and other reasons to minimize or exaggerate psychological disturbance, it becomes especially important to identify the influence of response bias in self-report of adjustment. This study investigated the susceptibility of three commonly used self-report pain assessment measures to response bias., Design: This study used a within-subjects (asymptomatic subjects) design with two experimental conditions and nonequivalent control group (chronic pain patients)., Subjects: Experimental group: 40 students enrolled in an occupational therapy program at a major southeastern United States university., Control Group: 200 subjects referred to a multidisciplinary pain clinic at a major teaching hospital., Measures: Coping Strategies Questionnaire, Multidimensional Pain Inventory, and Pain Beliefs and Perceptions Inventory., Results: With few exceptions, asymptomatic subjects scored significantly differently on these measures while portraying themselves as either coping well or coping poorly. In addition, when using the "coping poorly" response set, asymptomatic subjects reproduced scores similar to those of symptomatic chronic pain patients., Conclusion: The susceptibility to manipulation appeared constant across the three measures, a finding that highlighted the difficulties clinicians and researchers encounter in accurate interpretation of results from these measures in the absence of validity indicators. This study also emphasizes the ease with which subjects with sufficient motivation can present themselves in an untruthful and manipulative manner and can generate scores that are, on their own, difficult to distinguish from those of a group of typical chronic pain patients.

Objective: The purpose of our study was to investigate whether Minnesota Multiphasic Personality Inventory-2 cluster solutions of chronic low-back pain patients would replicate those found in previous research with the Minnesota Multiphasic Personality Inventory., Setting: A multidisciplinary pain clinic in the southeastern United States., Patients: The subjects were 201 chronic low-back pain patients who had suffered a work-related back injury., Outcome Measures: The Minnesota Multiphasic Personality Inventory-2., Results: We found four relatively homogeneous subgroups of chronic low-back pain patients that were similar to those identified by previous researchers using data collected with the Minnesota Multiphasic Personality Inventory., Conclusion: These findings indicate that interpretations of the Minnesota Multiphasic Personality Inventory-2 should parallel those of the Minnesota Multiphasic Personality Inventory for chronic low-back pain patients. They further suggest that the results of Minnesota Multiphasic Personality Inventory-based studies are also applicable to Minnesota Multiphasic Personality Inventory-2.