Fibromyalgia Syndrome in Chronic Disabling Occupational Musculoskeletal Disorders: Prevalence, Risk Factors, and Posttreatment Outcomes

Data-Driven Path Analytic Modeling to Understand Underlying Mechanisms in COVID-19 Survivors Suffering from Long-Term Post-COVID Pain: A Spanish Cohort Study

Pain can be present in up to 50% of people with post-COVID-19 condition. Understanding the complexity of post-COVID pain can help with better phenotyping of this post-COVID symptom. The aim of this study is to describe the complex associations between sensory-related, psychological, and cognitive variables in previously hospitalized COVID-19 survivors with post-COVID pain, recruited from three hospitals in Madrid (Spain) by using data-driven path analytic modeling. Demographic (i.e., age, height, and weight), sensory-related (intensity or duration of pain, central sensitization-associated symptoms, and neuropathic pain features), psychological (anxiety and depressive levels, and sleep quality), and cognitive (catastrophizing and kinesiophobia) variables were collected in a sample of 149 subjects with post-COVID pain. A Bayesian network was used for structural learning, and the structural model was fitted using structural equation modeling (SEM). The SEM model fit was excellent: RMSEA < 0.001, CFI = 1.000, SRMR = 0.063, and NNFI = 1.008. The only significant predictor of post-COVID pain was the level of depressive symptoms (β=0.241, p = 0.001). Higher levels of anxiety were associated with greater central sensitization-associated symptoms by a magnitude of β=0.406 (p = 0.008). Males reported less severe neuropathic pain symptoms (−1.50 SD S-LANSS score, p < 0.001) than females. A higher level of depressive symptoms was associated with worse sleep quality (β=0.406, p < 0.001), and greater levels of catastrophizing (β=0.345, p < 0.001). This study presents a model for post-COVID pain where psychological factors were related to central sensitization-associated symptoms and sleep quality. Further, maladaptive cognitions, such as catastrophizing, were also associated with depression. Finally, females reported more neuropathic pain features than males. Our data-driven model could be leveraged in clinical trials investigating treatment approaches in COVID-19 survivors with post-COVID pain and can represent a first step for the development of a theoretical/conceptual framework for post-COVID pain.

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.

Translation, cross-cultural adaptation, and measurement properties of the Nepali version of the central sensitization inventory (CSI)

BACKGROUND

Central sensitization is thought to be an important contributing factor in many chronic pain disorders. The Central Sensitization Inventory (CSI) is a patient-reported measure frequently used to assess symptoms related to central sensitization. The aims of the study were to translate and cross-culturally adapt the CSI into Nepali (CSI-NP) and assess its measurement properties.

METHODS

The CSI was translated into Nepali using recommended guidelines. The CSI-NP was then administered on 100 Nepalese adults with sub-acute and chronic musculoskeletal pain with additional demographic and pain-related questions. The CSI-Nepali was administered again about 2 weeks later. Four measurement properties of the CSI-NP were evaluated: (1) internal consistency using Cronbach's alpha, (2) test-retest reliability using intraclass correlation coefficient (ICC2,1), (3) measurement errors, and (4) construct validity testing five a priori hypotheses. Confirmation of construct validity was determined if a minimum of 75% of the hypotheses were met.

RESULTS

The CSI was successfully translated into Nepali. Internal consistency and test-retest reliability were both excellent (Cronbach's alpha = 0.91, and ICC = 0.98). The standard error of measurement was 0.31 and the smallest detectable change was 0.86. Four out of five (80%) a priori hypotheses were met, confirming the construct validity: the CSI-NP correlated strongly with the Pain Catastrophizing Scale total scores (r = 0.50); moderately with the total number of pain descriptors (r = 0.35); weakly with the Numerical Rating Scale (r = 0.25); and women had significantly higher CSI scores than men. However, the CSI scores did not correlate significantly with the total duration of pain, as hypothesized (r = 0.10).

CONCLUSIONS

The Nepali translation of the CSI demonstrated excellent reliability and construct validity in adults with musculoskeletal pain. It is now available to Nepali health care providers to help assess central sensitization-related signs and symptoms in individuals with musculoskeletal pain in research or clinical practice to advance the understanding of central sensitization in Nepalese samples.

Decreased Chronic Widespread Pain on Nonworking Days Might Help Differentiate Work-Related Musculoskeletal Disorders From Fibromyalgia: A Cross-Sectional Study of Working Females

Objectives

This study aims to investigate whether fibromyalgia (FM) and work-related musculoskeletal disorders can be differentiated in working females by comparing their pain on nonworking and working days.

Patients and methods

The study included 142 female workers (mean age 30.0±6.5 years; range, 18 to 50 years) from five different work areas: 27 factory workers, 27 janitors, 25 data automation employees, 31 nurses, and 32 physiotherapists. Demographic characteristics were recorded. FM was diagnosed according to 2016 criteria of the American College of Rheumatology. The extended version of the Nordic Musculoskeletal Questionnaire was used to evaluate the participants’ musculoskeletal complaints and the severity of their pain. Pain was assessed with visual analog scale (VAS) scores on working and nonworking days. Differences in the participants’ VAS-Pain on working and nonworking days were compared. Sensitivity, specificity, receiver operating characteristic (ROC) curve and area under the curve (AUC) were used.

Results

Of the 142 working females, 32 (22.5%) were diagnosed with FM. There was a significant difference in nonworking day VAS-Pain scores between the FM patients and the work-related musculoskeletal disorder patients (p<0.001). Analysis of ROC curve for VAS-Pain difference scores yielded AUC of 0.860 (95% confidence interval=0.774–0.945) (p<0.001). ROC analysis identified 1.5 centimeters of VAS-Pain difference score as the cut-point for differentiating work-related musculoskeletal disorders and FM resulting in sensitivity of 97% and specificity of 96%. FM patients had significantly higher rates of positive answers to “visit health professionals,” “take medication,” and “sick leave” questions compared to patients with work-related musculoskeletal disorders (p<0.001).

Conclusion

The amount of the decrease in pain on nonworking days may help differentiate work-related musculoskeletal disorders from FM in working females. Therefore, evaluating pain on nonworking days may help clinicians diagnose and treat FM correctly.

Self-reported disability in women with fibromyalgia from a tertiary care center

Background

The World Health Organization Disability Assessment Schedule (WHODAS) 2.0 is a generic instrument to assess disability. Pain and psychological factors seem to play a pronounced disabling role in fibromyalgia (FM). There are few studies that investigate the factors associated with disability in patients with fibromyalgia from the patient’s perspective. Information about FM disability using self-reported questionnaires is limited. This study aimed to assess the relationship between the ordinal response variable (degree of disability), and four explanatory variables: pain intensity, depression, anxiety, and alexithymia.

Methods

One hundred fifteen women with FM were enrolled in the cross-sectional study. For the assessment of disability the WHODAS 2.0 (36-item version) was used. Univariate and multivariate (ordinal logistic regression) analyses were performed to assess the relationship between pain (Visual Analogue Scale), depression and anxiety (Hospital Anxiety and Depression Scale), alexithymia (Modified Toronto Alexithymia Scale) and disability.

Results

Disability was detected by global WHODAS score in 114 patients (99%), with the corresponding percentages for mild, moderate and severe disability being 11.3, 46.96 and 40.87%, respectively. Global WHODAS score was more severe among subjects with depression (50 vs 36.4, p < 0.001, effect size = 0.33) and alexithymia (50 vs 33.6, p < 0.001, effect size = 0.38). Pain intensity mean scores for mild, moderate and severe disability were 5.0, 6.1 and 7.3, respectively (p < 0.001, omega-squared = 0.12). Pain intensity explained the global disability degree and its domains except for the cognitive one. Whereas, depression explained cognitive and personal relation domains. On the other hand, alexithymia explained global disability degree and all domains of WHODAS 2.0 questionnaire.

Conclusions

Most of the patients with fibromyalgia perceived themselves with moderate to severe disability. The main explanatory variables of the perceived disability were the pain intensity and psychological factors (alexithymia and depression).

Comorbid fibromyalgia: A qualitative review of prevalence and importance

Fibromyalgia (FM) may be an unrecognized cause of suffering for persons with an array of medical conditions. This is especially true for illness that is characterized by pain of any nature. Once believed to be a unique diagnosis, FM is recently reported to occur concomitantly with various rheumatic diseases, and importantly adversely impacts global health status. However, there is increasing report of FM associated with other diseases that are not defined by chronic pain. This qualitative review examines the evidence for comorbid FM in illness, and where available the effect of FM on the primary disease. Other than for musculoskeletal disorders, the published literature reporting an association of FM with illness is limited with scanty reports for some neurological, gastrointestinal, mental health and other overlapping pain conditions. Comorbid FM adversely affects both health status and outcome for rheumatic diseases, but with limited study in other diseases. When unrecognized, comorbid FM may be mistaken as poor control of the primary disease, leading to incorrect treatment decisions. FM may be a neglected condition that pervades many conditions and may contribute to the burden of illness. Physicians should be alert to the possibility of comorbid FM, and symptoms of FM should be specifically addressed.

SIGNIFICANCE

Comorbid fibromyalgia (FM) in other medical conditions is largely unrecognized. When reported as accompanying rheumatic diseases, FM adversely affects global health status. With limited reports of comorbid FM with other conditions, neglect to diagnose comorbid FM may misdirect treatments.

Use of the Central Sensitization Inventory (CSI) as a treatment outcome measure for patients with chronic spinal pain disorder in a functional restoration program

BACKGROUND CONTEXT

The Central Sensitization Inventory (CSI) is a valid and reliable patient-reported instrument designed to identify patients whose presenting symptoms may be related to central sensitization (CS). Part A of the CSI measures a full array of 25 somatic and emotional symptoms associated with CS, and Part B asks if patients have previously been diagnosed with one or more specific central sensitivity syndromes (CSSs) and related disorders. The CSI has previously been validated in a group of patients with chronic pain who were screened by a trained psychiatrist for specific CSS diagnoses. It is currently unknown if the CSI can be a useful treatment-outcome assessment tool for patients with chronic spinal pain disorder (CSPD) who are not screened for comorbid CSSs. It is known, however, that previous studies have identified CS-related symptoms, and comorbid CSSs, in subsets of patients with CSPDs. Studies have also shown that CS-related symptoms can be influenced by cognitive and psychosocial factors, including abuse history in both childhood and adulthood, sleep disturbance, catastrophic and fear-avoidant cognitions, and symptoms of depression and anxiety.

PURPOSE

This study aimed to evaluate CSI scores, and their associations with other clinically relevant psychosocial variables, in a cohort of patients with CSPD who entered and completed a functional restoration program.

STUDY DESIGN/SETTING

A retrospective study of prospectively collected data from a cohort study of patients with CSPD, who completed the CSI at admission to, and discharge from, an interdisciplinary function restoration program (FRP) was carried out.

PATIENT SAMPLE

A cohort of 763 patients with CSPD comprised the study sample.

OUTCOME MEASURES

Clinical interviews evaluated mood disorders and abuse history. A series of self-reported measures evaluated comorbid psychosocial symptoms, including pain intensity, pain-related anxiety, depressive symptoms, somatization symptoms, perceived disability, and sleep disturbance, at FRP admission and discharge.

METHODS

Patients were grouped into five severity level groups, from mild to extreme, based on total CSI scores, at FRP admission, and then again at discharge. The FRP included a quantitatively directed and medically supervised exercise process, as well as a multimodal psychosocial disability management component.

RESULTS

The CSI severity groups were strongly associated with Major Depressive Disorder and previous abuse history (p<.01), which are known risk factors for CS-related symptoms and diagnoses. The CSI scores were also strongly associated with patient-reported CSS diagnoses on CSI Part B. The percentage of patients who reported a comorbid CSS diagnosis increased in each higher CSI-severity group, from 11% in the Subclinical group, to 56% in the Extreme group. The CSI severity groups were significantly related to other CS-related patient-reported symptoms, including pain intensity, pain-related anxiety, depressive symptoms, somatization symptoms, perceived disability, and sleep disturbance (p's<.001). The CSI scores, along with all other psychosocial measures, decreased at treatment discharge.

CONCLUSIONS

In the present study, admission CSI scores were highly associated with previous CSS diagnoses, CS-related symptoms, and clinically relevant patient-reported psychosocial variables. All psychosocial variables, as well as scores on the CSI, were significantly improved at FRP discharge. The CSI may have important clinical utility, as a screener and as a treatment outcome measure, for patients with CSPD participating in an interdisciplinary FRP.

Work Ability in Fibromyalgia: An Update in the 21st Century

BACKGROUND

Fibromyalgia (FM) is characterized by persistent widespread pain, increased pain sensitivity and tenderness. People with FM also report activity limitations and impaired work ability.

OBJECTIVE

This article aims to compile the findings of recently published research on work ability in people with fibromyalgia, and to present how work ability is influenced by various aspects.

METHODS

A systematic search of the literature published from the year 2000 and onwards was conducted. Thirtyfour articles were included in the review.

RESULT

Symptom severity was found to influence work ability in people with FM. Physically demanding jobs and work tasks were especially troublesome and were reported to constitute higher risks pof work disability. Working people with FM seemed to hold a careful balancing act to manage the risk of overload where well-functioning strategies such as making a career change, working part-time, and developing personal skills were necessary for managing work, in the short- and long term. The support of management and colleagues enabled people with FM to manage the risk of overload at work. Treatment studies evaluating work disability as outcome in FM are scarce. None of the included studies presented any effects on measures of sick-leave or work disability compared with a control group.

CONCLUSION

More studies of treatment effects on outcomes related to work ability in people with FM, and more longitudinal studies to explore long-term effects of symptoms on work ability and sick leave, are needed in order to be able to plan evidence based rehabilitation to improve or maintain work ability in people with FM.

Fibromyalgia

Fibromyalgia is a common illness characterized by chronic widespread pain, sleep problems (including unrefreshing sleep), physical exhaustion and cognitive difficulties. The definition, pathogenesis and treatment are controversial, and some even contest the existence of this disorder. In 1990, the American College of Rheumatology (ACR) defined classification criteria that required multiple tender points (areas of tenderness occurring in muscles and muscle-tendon junctions) and chronic widespread pain. In 2010, the ACR preliminary diagnostic criteria excluded tender points, allowed less extensive pain and placed reliance on patient-reported somatic symptoms and cognitive difficulties. Fibromyalgia occurs in all populations worldwide, and symptom prevalence ranges between 2% and 4% in the general population. The prevalence of people who are actually diagnosed with fibromyalgia ('administrative prevalence') is much lower. A model of fibromyalgia pathogenesis has been suggested in which biological and psychosocial variables interact to influence the predisposition, triggering and aggravation of a chronic disease, but the details are unclear. Diagnosis requires the history of a typical cluster of symptoms and the exclusion of a somatic disease that sufficiently explains the symptoms by medical examination. Current evidence-based guidelines emphasize the value of multimodal treatments, which encompass both non-pharmacological and selected pharmacological treatments tailored to individual symptoms, including pain, fatigue, sleep problems and mood problems. For an illustrated summary of this Primer, visit: http://go.nature.com/LIBdDX.

Do comorbid fibromyalgia diagnoses change after a functional restoration program in patients with chronic disabling occupational musculoskeletal disorders?

STUDY DESIGN

A retrospective study of prospectively collected data.

OBJECTIVE

To determine whether comorbid fibromyalgia, identified in patients with chronic disabling occupational musculoskeletal disorders (CDOMDs), resolves with a functional restoration program (FRP).

SUMMARY OF BACKGROUND DATA

Fibromyalgia involves widespread bodily pain and tenderness to palpation. In recent studies, 23% to 41% of patients with CDOMDs entering an FRP had comorbid fibromyalgia, compared with population averages of 2% to 5%. Few studies have examined whether fibromyalgia diagnoses resolve with any treatment, and none have investigated diagnosis responsiveness to an FRP.

METHODS

A consecutive cohort of patients with CDOMDs (82% with spinal disorders and all reporting chronic spinal pain) and comorbid fibromyalgia (N = 117) completed an FRP, which included quantitatively directed exercise progression and multimodal disability management. Diagnosis responsiveness, evaluated at discharge, created 2 groups: those who retained fibromyalgia and those who did not. These groups were compared with chronic regional lumbar pain only patients (LO group, n = 87), lacking widespread pain and fibromyalgia.

RESULTS

Of the patients with comorbid fibromyalgia, 59% (n = 69) retained the fibromyalgia diagnosis (RFM group) and 41% (n = 48) lost the fibromyalgia diagnosis (LFM group) at discharge. Although all 3 groups reported decreased pain intensity, disability, and depressive symptoms from admission to discharge, RFM patients reported higher symptom levels than the LFM and LO groups at discharge. The LFM and LO groups were statistically similar. At 1-year follow-up, LO patients demonstrated higher work retention than both fibromyalgia groups (P < 0.03).

CONCLUSION

Despite a significant comorbid fibromyalgia prevalence in a cohort of patients with CDOMDs entering an FRP, 41% of patients with an initial fibromyalgia diagnosis no longer met diagnostic criteria for fibromyalgia at discharge and were indistinguishable from LO patients on pain, disability, and depression symptoms. However, both fibromyalgia groups (LFM and RFM) had lower work retention than LO patients 1 year later, suggesting that an FRP may suppress symptoms of fibromyalgia in a subset of patients, but prolonged fibromyalgia-related disability may be more difficult to overcome.

LEVEL OF EVIDENCE

2.

The phenotypic and genetic signatures of common musculoskeletal pain conditions

Musculoskeletal pain conditions, such as fibromyalgia and low back pain, tend to coexist in affected individuals and are characterized by a report of pain greater than expected based on the results of a standard physical evaluation. The pathophysiology of these conditions is largely unknown, we lack biological markers for accurate diagnosis, and conventional therapeutics have limited effectiveness. Growing evidence suggests that chronic pain conditions are associated with both physical and psychological triggers, which initiate pain amplification and psychological distress; thus, susceptibility is dictated by complex interactions between genetic and environmental factors. Herein, we review phenotypic and genetic markers of common musculoskeletal pain conditions, selected based on their association with musculoskeletal pain in previous research. The phenotypic markers of greatest interest include measures of pain amplification and 'psychological' measures (such as emotional distress, somatic awareness, psychosocial stress and catastrophizing). Genetic polymorphisms reproducibly linked with musculoskeletal pain are found in genes contributing to serotonergic and adrenergic pathways. Elucidation of the biological mechanisms by which these markers contribute to the perception of pain in these patients will enable the development of novel effective drugs and methodologies that permit better diagnoses and approaches to personalized medicine.

The Central Sensitization Inventory (CSI): establishing clinically significant values for identifying central sensitivity syndromes in an outpatient chronic pain sample

Central sensitization (CS) is a proposed physiological phenomenon in which central nervous system neurons become hyperexcitable, resulting in hypersensitivity to both noxious and non-noxious stimuli. The term central sensitivity syndrome (CSS) describes a group of medically indistinct (or nonspecific) disorders, such as fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome, for which CS may be a common etiology. In a previous study, the Central Sensitization Inventory (CSI) was introduced as a screening instrument for clinicians to help identify patients with a CSS. It was found to have high reliability and validity (test-retest reliability = .82; Cronbach's alpha = .88). The present study investigated a cohort of 121 patients who were referred to a multidisciplinary pain center, which specializes in the assessment and treatment of complex pain and psychophysiological disorders, including CSSs. A large percentage of patients (n = 89, 74%) met clinical criteria for one or more CSSs, and CSI scores were positively correlated with the number of diagnosed CSSs. A receiver operating characteristic analysis determined that a CSI score of 40 out of 100 best distinguished between the CSS patient group and a nonpatient comparison sample (N = 129) (area under the curve = .86, sensitivity = 81%, specificity = 75%).

PERSPECTIVE

The CSI is a new self-report screening instrument to help identify patients with CSSs, including fibromyalgia. The present study investigated CSI scores in a heterogeneous pain population with a large percentage of CSSs, and a normative nonclinical sample to determine a clinically relevant cutoff value.

Genetics and Gene Expression Involving Stress and Distress Pathways in Fibromyalgia with and without Comorbid Chronic Fatigue Syndrome

In complex multisymptom disorders like fibromyalgia syndrome (FMS) and chronic fatigue syndrome (CFS) that are defined primarily by subjective symptoms, genetic and gene expression profiles can provide very useful objective information. This paper summarizes research on genes that may be linked to increased susceptibility in developing and maintaining these disorders, and research on resting and stressor-evoked changes in leukocyte gene expression, highlighting physiological pathways linked to stress and distress. These include the adrenergic nervous system, the hypothalamic-pituitary-adrenal axis and serotonergic pathways, and exercise responsive metabolite-detecting ion channels. The findings to date provide some support for both inherited susceptibility and/or physiological dysregulation in all three systems, particularly for catechol-O-methyl transferase (COMT) genes, the glucocorticoid and the related mineralocorticoid receptors (NR3C1, NR3C2), and the purinergic 2X4 (P2X4) ion channel involved as a sensory receptor for muscle pain and fatigue and also in upregulation of spinal microglia in chronic pain models. Methodological concerns for future research, including potential influences of comorbid clinical depression and antidepressants and other medications, on gene expression are also addressed.

The development and psychometric validation of the central sensitization inventory

Central sensitization (CS) has been proposed as a common pathophysiological mechanism to explain related syndromes for which no specific organic cause can be found. The term "central sensitivity syndrome (CSS)" has been proposed to describe these poorly understood disorders related to CS. The goal of this investigation was to develop the Central Sensitization Inventory (CSI), which identifies key symptoms associated with CSSs and quantifies the degree of these symptoms. The utility of the CSI, to differentiate among different types of chronic pain patients who presumably have different levels of CS impairment, was then evaluated. Study 1 demonstrated strong psychometric properties (test-retest reliability = 0.817; Cronbach's alpha = 0.879) of the CSI in a cohort of normative subjects. A factor analysis (including both normative and chronic pain subjects) yielded 4 major factors (all related to somatic and emotional symptoms), accounting for 53.4% of the variance in the dataset. In Study 2, the CSI was administered to 4 groups: fibromyalgia (FM); chronic widespread pain without FM; work-related regional chronic low back pain (CLBP); and normative control group. Analyses revealed that the patients with FM reported the highest CSI scores and the normative population the lowest (P < 0.05). Analyses also demonstrated that the prevalence of previously diagnosed CSSs and related disorders was highest in the FM group and lowest in the normative group (P < 0.001). Taken together, these 2 studies demonstrate the psychometric strength, clinical utility, and the initial construct validity of the CSI in evaluating CS-related clinical symptoms in chronic pain populations.