The epidemiology of chronic generalized musculoskeletal pain

Mechanisms of pain in aging and age-related conditions: Focus on caregivers

Pain is a complex, subjective experience that can significantly impact quality of life, particularly in aging individuals, by adversely affecting physical and emotional well-being. Whereas acute pain usually serves a protective function, chronic pain is a persistent pathological condition that contributes to functional deficits, cognitive decline, and emotional disturbances in the elderly. Despite substantial progress that has been made in characterizing age-related changes in pain, complete mechanistic details of pain processing mechanisms in the aging patient remain unknown. Pain is particularly under-recognized and under-managed in the elderly, especially among patients with Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other age-related conditions. Furthermore, difficulties in assessing pain in patients with AD/ADRD and other age-related conditions may contribute to the familial caregiver burden. The purpose of this article is to discuss the mechanisms and risk factors for chronic pain development and persistence, with a particular focus on age-related changes. Our article also highlights the importance of caregivers working with aging chronic pain patients, and emphasizes the urgent need for increased legislative awareness and improved pain management in these populations to substantially alleviate caregiver burden.

Understanding the pattern of musculoskeletal pain and its contributing factors among Hajj pilgrims

BACKGROUND

Hajj is a series of rituals that are done in specific areas and periods in Mecca. Performing Hajj requires a great amount of physical demand which may result in musculoskeletal pain (MSP) in different age groups.

OBJECTIVE

To estimate the prevalence of MSP and understand its pattern via exploring the factors that could be associated with muscular pain among pilgrims in the 2022 Hajj.

METHODS

A web-based survey was distributed during the annual Hajj mass gathering. Pilgrims were recruited from Hajj ritual sites. The collected data included demographics, musculoskeletal pain at ten anatomical body sites, and physical activity (PA) level. Descriptive and inferential statistics were used to analyze the data at a 0.05 significance level.

RESULTS

A total of 248 pilgrims participated in the study. The mean age of the sample was 43.49±12.70 years. Of all pilgrims, 78.6% had reported MSP in at least one anatomical body site during performing Hajj. Results revealed that Pilgrims were more likely to have MSP in the lower limb while performing Hajj rituals where the most prevalent reported pain was in the legs (46% ), followed by the lower back (45% ), knees (37% ), and ankles/feet (30% ). Age, sex, and PA were not significantly associated with MSP except the BMI was found to be a significant factor related to MSP among pilgrims (p <0.05).

CONCLUSION

Many pilgrims exhibited pain in at least one body part. Although physical fitness recommendations are published in the Saudi Ministry of Health, MSP preventative measures need to be disseminated by organizations and interested parties worldwide.

Pain and the biochemistry of fibromyalgia: patterns of peripheral cytokines and chemokines contribute to the differentiation between fibromyalgia and controls and are associated with pain, fat infiltration and content

Objectives

This explorative study analyses interrelationships between peripheral compounds in saliva, plasma, and muscles together with body composition variables in healthy subjects and in fibromyalgia patients (FM). There is a need to better understand the extent cytokines and chemokines are associated with body composition and which cytokines and chemokines differentiate FM from healthy controls.

Methods

Here, 32 female FM patients and 30 age-matched female healthy controls underwent a clinical examination that included blood sample, saliva samples, and pain threshold tests. In addition, the subjects completed a health questionnaire. From these blood and saliva samples, a panel of 68 mainly cytokines and chemokines were determined. Microdialysis of trapezius and erector spinae muscles, phosphorus-31 magnetic resonance spectroscopy of erector spinae muscle, and whole-body magnetic resonance imaging for determination of body composition (BC)-i.e., muscle volume, fat content and infiltration-were also performed.

Results

After standardizing BC measurements to remove the confounding effect of Body Mass Index, fat infiltration and content are generally increased, and fat-free muscle volume is decreased in FM. Mainly saliva proteins differentiated FM from controls. When including all investigated compounds and BC variables, fat infiltration and content variables were most important, followed by muscle compounds and cytokines and chemokines from saliva and plasma. Various plasma proteins correlated positively with pain intensity in FM and negatively with pain thresholds in all subjects taken together. A mix of increased plasma cytokines and chemokines correlated with an index covering fat infiltration and content in different tissues. When muscle compounds were included in the analysis, several of these were identified as the most important regressors, although many plasma and saliva proteins remained significant.

Discussion

Peripheral factors were important for group differentiation between FM and controls. In saliva (but not plasma), cytokines and chemokines were significantly associated with group membership as saliva compounds were increased in FM. The importance of peripheral factors for group differentiation increased when muscle compounds and body composition variables were also included. Plasma proteins were important for pain intensity and sensitivity. Cytokines and chemokines mainly from plasma were also significantly and positively associated with a fat infiltration and content index.

Conclusion

Our findings of associations between cytokines and chemokines and fat infiltration and content in different tissues confirm that inflammation and immune factors are secreted from adipose tissue. FM is clearly characterized by complex interactions between peripheral tissues and the peripheral and central nervous systems, including nociceptive, immune, and neuroendocrine processes.

Prevalence of temporomandibular disorders in the Brazilian population: A systematic review and meta-analysis

This systematic review aimed to assess the prevalence of temporomandibular disorders (TMD) in the Brazilian population, with studies that used the RDC/TMD or DC/TMD as diagnostic tools. A total of 6365 people from 11 studies were included. Sample mean age ranged from 12 to 69.5 years. The pooled prevalence of TMD was 33.6% (95% CI 31.5-35.8; I2 = 37.2). Prevalence of TMD was higher in females (37.0%) than in males (29.3%). Our results indicate that TMD is a prevalent condition across Brazil's territories. The results from this meta-analysis can help calculate more accurate sample sizes for future studies.

Meditative-based diaphragmatic breathing vs. vagus nerve stimulation in the treatment of fibromyalgia-A randomized controlled trial: Body vs. machine

IMPORTANCE

Vagus nerve innervation via electrical stimulation and meditative-based diaphragmatic breathing may be promising treatment avenues for fibromyalgia.

OBJECTIVE

Explore and compare the treatment effectiveness of active and sham transcutaneous vagus nerve stimulation (tVNS) and meditative-based diaphragmatic breathing (MDB) for fibromyalgia.

DESIGN

Participants enrolled from March 2019-October 2020 and randomly assigned to active tVNS (n = 28), sham tVNS (n = 29), active MDB (n = 29), or sham MDB (n = 30). Treatments were self-delivered at home for 15 min/morning and 15 min/evening for 14 days. Follow-up was at 2 weeks.

SETTING

Outpatient pain clinic in Oslo, Norway.

PARTICIPANTS

116 adults aged 18-65 years with severe fibromyalgia were consecutively enrolled and randomized. 86 participants (74%) had an 80% treatment adherence and 107 (92%) completed the study at 2 weeks; 1 participant dropped out due to adverse effects from active tVNS.

INTERVENTIONS

Active tVNS is placed on the cymba conchae of the left ear; sham tVNS is placed on the left earlobe. Active MDB trains users in nondirective meditation with deep breathing; sham MDB trains users in open-awareness meditation with paced breathing.

MAIN OUTCOMES AND MEASURES

Primary outcome was change from baseline in ultra short-term photoplethysmography-measured cardiac-vagal heart rate variability at 2 weeks. Prior to trial launch, we hypothesized that (1) those randomized to active MDB or active tVNS would display greater increases in heart rate variability compared to those randomized to sham MDB or sham tVNS after 2-weeks; (2) a change in heart rate variability would be correlated with a change in self-reported average pain intensity; and (3) active treatments would outperform sham treatments on all pain-related secondary outcome measures.

RESULTS

No significant across-group changes in heart rate variability were found. Furthermore, no significant correlations were found between changes in heart rate variability and average pain intensity during treatment. Significant across group differences were found for overall FM severity yet were not found for average pain intensity.

CONCLUSIONS AND RELEVANCE

These findings suggest that changes in cardiac-vagal heart rate variability when recorded with ultra short-term photoplethysmography in those with fibromyalgia may not be associated with treatment-specific changes in pain intensity. Further research should be conducted to evaluate potential changes in long-term cardiac-vagal heart rate variability in response to noninvasive vagus nerve innervation in those with fibromyalgia.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT03180554, Identifier: NCT03180554.

Lavage Volume of Arthrocentesis in the Management of Temporomandibular Disorders: A Systematic Review and Meta-Analysis

The aim of this study was to investigate the most effective lavage volume of arthrocentesis in the management of temporomandibular disorders. A comprehensive electronic search, based on the PRISMA guidelines, was performed, which included a computer search with specific keywords, a reference list search and a manual search. The inclusion criteria were the following: a randomized controlled trial, at least 20 subjects who underwent arthrocentesis, mention of the irrigation materials used for the arthrocentesis, mention of the irrigation volumes used for the arthrocentesis, MMO and pain measured as VAS or NRS, were reported as outcome figures, mention of a specific diagnosis or signs and symptoms, and inclusion of the data on the MMO or VAS/NRS at 6-month follow-up. Sixteen publications were enrolled in the meta-analysis, comparing arthrocentesis with a lavage volume <150 mL and arthrocentesis with a lavage volume ≥150 mL, in the efficacy of the improvement in the mouth opening and pain reduction. The results revealed the group with a lavage volume <150 mL had a greater improvement in the mouth opening and pain reduction. However, results are to be interpreted with caution, due to the paucity of the randomized controlled literature and other confounding factors. Further high-quality studies are required to provide a better conclusion to the treatment outcomes of the different lavage volumes.

Fibromyalgia: Associations Between Fat Infiltration, Physical Capacity, and Clinical Variables

Background

Obesity is a risk factor for the development of fibromyalgia (FM) and generally most studies report increased Body Mass Index (BMI) in FM. Obesity in FM is associated with a worse clinical presentation. FM patients have low physical conditioning and obesity further exacerbates these aspects. Hitherto studies of FM have focused upon a surrogate for overall measure of fat content, ie, BMI. This study is motivated by that ectopic fat and adipose tissues are rarely investigated in FM including their relationships to physical capacity variables. Moreover, their relationships to clinical variables including are not known. Aims were to 1) compare body composition between FM and healthy controls and 2) investigate if significant associations exist between body composition and physical capacity aspects and important clinical variables.

Methods

FM patients (n = 32) and healthy controls (CON; n = 30) underwent a clinical examination that included pressure pain thresholds and physical tests. They completed a health questionnaire and participated in whole-body magnetic resonance imaging (MRI) to determine body composition aspects.

Results

Abdominal adipose tissues, muscle fat, and BMI were significantly higher in FM, whereas muscle volumes of quadriceps were smaller. Physical capacity variables correlated negatively with body composition variables in FM. Both body composition and physical capacity variables were significant regressors of group belonging; the physical capacity variables alone showed stronger relationships with group membership. A mix of body composition variables and physical capacity variables were significant regressors of pain intensity and impact in FM. Body composition variables were the strongest regressors of blood pressures, which were increased in FM.

Conclusion

Obesity has a negative influence on FM symptomatology and increases the risk for other serious conditions. Hence, obesity, dietary habits, and physical activity should be considered when developing clinical management plans for patients with FM.

Consensus evidence-based clinical practice recommendations for the management of fibromyalgia

Background

Because of the subjective character of symptoms, absence of a diagnostic test, modest response to treatments, and, at times, patient reports of important functional disability, fibromyalgia remains a challenge for the treating health care professionals in the standard clinical practice. The aim of this study was to develop an up-to-date consensus and evidence-based clinical practice guidelines for a treat-to-target management of fibromyalgia. Fifteen key clinical questions were identified by a scientific committee according to the Patient/Population, Intervention, Comparison, and Outcomes (PICO) approach. A literature review team performed a systematic review to summarize the evidence advocating the benefits and harms of available pharmacologic and nonpharmacologic therapies for fibromyalgia. Subsequently, recommendations were formulated. The level of evidence was determined for each section using the Oxford Centre for Evidence-based Medicine (CEBM) system. A 3-round Delphi process was conducted with 16 experts. All rounds were conducted online. A consensus was achieved on the direction and the strength of the recommendations.

Results

An online questionnaire was sent to an expert panel who participated in the three rounds (response rate 100%). At the end of round 3, a total of fifteen recommendation items, categorized into 10 sections to address the main fibromyalgia categories, were obtained. Agreement with the recommendations (ranks 7–9) ranged from 85 to 100%. Consensus was reached (i.e., ≥ 80% of respondents strongly agreed or agreed) on the wording of all the 15 clinical standards identified by the scientific committee. An algorithm for the management of fibromyalgia has been suggested.

Conclusions

These recommendations provide an updated consensus on both the non-pharmacological and the pharmacological treatments of fibromyalgia. The provided strategies to reach optimal treat-to-target outcomes in common clinical scenarios are based on a combination of evidence and expert opinions. Best treatment decisions should be tailored to each individual patient situation.

Hippocampal volume, FKBP5 genetic risk alleles, and childhood trauma interact to increase vulnerability to chronic multisite musculoskeletal pain

Chronic multisite musculoskeletal pain (CMP) is common and highly morbid. However, vulnerability factors for CMP are poorly understood. Previous studies have independently shown that both small hippocampal brain volume and genetic risk alleles in a key stress system gene, FKBP5, increase vulnerability for chronic pain. However, little is known regarding the relationship between these factors and CMP. Here we tested the hypothesis that both small hippocampal brain volume and FKBP5 genetic risk, assessed using the tagging risk variant, FKBP5rs3800373, increase vulnerability for CMP. We used participant data from 36,822 individuals with available genetic, neuroimaging, and chronic pain data in the UK Biobank study. Although no main effects were observed, the interaction between FKBP5 genetic risk and right hippocampal volume was associated with CMP severity (β = -0.020, p_raw = 0.002, p_adj = 0.01). In secondary analyses, severity of childhood trauma further moderated the relationship between FKBP5 genetic risk, right hippocampal brain volume, and CMP (β = -0.081, p = 0.016). This study provides novel evidence that both FKBP5 genetic risk and childhood trauma moderate the relationship between right hippocampal brain volume and CMP. The data increases our understanding of vulnerability factors for CMP and builds a foundation for further work assessing causal relationships that might drive CMP development.

Does difficulty in chewing induce subjective musculoskeletal symptoms? A case-control study

OBJECTIVES

Risk factors associated with the development of musculoskeletal disorders and symptoms remain an important issue worldwide. This study aimed to investigate the relationship between oral health problems such as difficulty chewing and the occurrence of stiff neck/shoulders (SN/S) and low back pain (LBP).

DESIGN

Case-control study.

SETTING AND PARTICIPANTS

This study was conducted from 1 April 2018 to 31 March 2020. The subjects were 77 341 workers among 646 281 workers from several employers in Japan.

OUTCOME MEASURES

Participants were asked to evaluate their subjective SN/S and LBP symptoms using a self-administered questionnaire.

METHODS

We defined the chewing condition using a questionnaire, and workers who responded with 'I can chew anything' were classified as the good condition group (GCG), and those who responded with 'Sometimes I have difficulty chewing due to problems with the teeth, gums, or bite' or 'I can hardly chew' were classified as the poor condition group (PCG). Setting the year 2018 as the baseline, we performed a logistic regression model using propensity score and inverse probability weighting (IPW) methods and chewing condition groups as explanatory variables and SN/S and LBP as objective variables.

RESULTS

The IPW-adjusted logistic regression model showed that the OR of SN/S was approximately 1.25 (95% CI 1.17 to 1.33) times higher in the PCG than that in the GCG (p<0.001). Similarly, the OR of LBP was about 1.37 (95% CI 1.27 to 1.48) times higher in the PCG than that in the GCG in the IPW-adjusted logistic regression model (p<0.001).

CONCLUSIONS

Our study suggests that the occurrence of SN/S and LBP symptoms in workers could be predicted depending on the presence of difficulty in chewing. Therefore, oral health and health guidance are gaining importance for the prevention of subjective musculoskeletal symptoms.

Spinal spatial integration of nociception and its functional role assessed via the nociceptive withdrawal reflex and psychophysical measures in healthy humans

Animal studies have previously shown that deep dorsal horn neurons play a role in the processing of spatial characteristics of nociceptive information in mammals. Human studies have supported the role of the spinal neurons; however, the mechanisms involved, and its significance, remain to be clarified. The aim of this study was to investigate spatial aspects of the spinal integration of concurrent nociceptive electrical stimuli in healthy humans using the Nociceptive Withdrawal Reflex (NWR) as an objective indication of spinal nociceptive processing. Fifteen healthy volunteers participated in the study. Electrical stimuli were delivered, using five electrodes located across the sole of the foot in a mediolateral disposition, as a single or double simultaneous stimuli with varying Inter-Electrode Distances (IEDs). The stimulation intensity was set at 1.5× NWR threshold (TA muscle). The size of the NWR was quantified in the 60-180 ms poststimulus window as a primary outcome measure. Psychophysical measures were secondary outcomes. Single stimulation elicited significantly smaller NWRs and perceived intensity than double stimulation (p < .01), suggesting the presence of spatial summation occurring within the spinal processing. During double stimulation, increasing the inter-electrode distance produced significantly smaller NWR sizes (p < .05) but larger pain intensity ratings (p < .05). By the NWR, spatial summation was shown to affect the nociceptive processing within the spinal cord. The inhibited motor response obtained when simultaneously stimulating the medial and lateral side of the sole of the foot suggests the presence of an inhibitory mechanism with a functional, behaviorally oriented function.

Double-blind, randomized, placebo-controlled crossover trial of alpha-lipoic acid for the treatment of fibromyalgia pain: the IMPALA trial

ABSTRACT

Fibromyalgia is a common and challenging chronic pain disorder with few, if any, highly effective and well-tolerated treatments. Alpha-lipoic acid (ALA) is a nonsedating antioxidant with evidence of efficacy in the treatment of symptomatic diabetic neuropathy that has not been evaluated in the setting of fibromyalgia treatment. Thus, we conducted a single-centre, proof-of-concept, randomized, placebo-controlled, crossover trial of ALA for the treatment of fibromyalgia. Twenty-seven participants were recruited, and 24 participants completed both treatment periods of the trial. The median maximal tolerated dose of ALA in this trial was 1663 mg/day. Treatment-emergent adverse events with ALA were infrequent and not statistically different from placebo. For the primary outcome of pain intensity, and for several other validated secondary outcomes, there were no statistically significant differences between placebo and ALA. A post hoc exploratory subgroup analysis showed a significant interaction between gender and treatment with a significant favourable placebo-ALA difference in pain for men, but not for women. Overall, the results of this trial do not provide any evidence to suggest promise for ALA as an effective treatment for fibromyalgia, which is predominantly prevalent in women. This negative clinical trial represents an important step in a collective strategy to identify new, better tolerated and more effective treatments for fibromyalgia.

Prevalence, burden of disease, and lost in health state utilities attributable to chronic musculoskeletal disorders and pain in Chile

Background

Musculoskeletal disorders are a leading cause of disability adjusted life years (DALY) in the world. We aim to describe the prevalence and to compare the DALYs and loss of health state utilities (LHSU) attributable to common musculoskeletal disorders in Chile.

Methods

We used data from the Chilean National Health Survey carried out in 2016–2017. Six musculoskeletal disorders were detected through the COPCOPRD questionnaire: chronic musculoskeletal pain, chronic low back pain, chronic shoulder pain, osteoarthritis of hip and knee, and fibromyalgia. We calculated the DALY for each disorder for 18 sex and age strata, and LHSU following an individual and population level approaches. We also calculated the fraction of LHSU attributable to pain.

Results

Chronic musculoskeletal pain disorder affects a fifth of the adult population, with a significant difference between sexes. Among specific musculoskeletal disorders highlights chronic low back pain with the highest prevalence. Musculoskeletal disorders are a significant cause of LHSU at the individual level, especially in the case of fibromyalgia. Chronic musculoskeletal pain caused 503,919 [283,940 - 815,132] DALYs in 2017, and roughly two hundred thousand LSHU at population level, which represents 9.7% [8.8–10.6] of the total LSHU occurred in that year. Discrepancy in the burden of musculoskeletal disorders was observed according to DALY or LSHU estimation. The pain and discomfort domain of LHSU accounted for around half of total LHSU in people with musculoskeletal disorders.

Conclusion

Chronic musculoskeletal pain is a major source of burden and LHSU. Fibromyalgia should deserve more attention in future studies. Using the attributable fraction offers a straightforward and flexible way to explore the burden of musculoskeletal disorders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10953-z.

Long-term trajectories of chronic musculoskeletal pain: a 21-year prospective cohort latent class analysis

ABSTRACT

Our knowledge of the prevalence, impact, and outcomes of chronic pain in the general population is predominantly based on studies over relatively short periods of time. The aim of this study was to identify and describe trajectories of the chronic pain status over a period of 21 years. Self-reported population data (n = 1858) from 5 timepoints were analyzed. Pain was categorized by: no chronic pain (NCP), chronic regional pain (CRP), and chronic widespread pain (CWP). Latent class growth analysis was performed for identification of trajectories and logistic regression analysis for identification of predictors for pain prognosis. Five trajectories were identified: (1) persistent NCP (57%), (2) migrating from NCP to CRP or CWP (5%), (3) persistent CRP or migration between CRP and NCP (22%), (4) migration from CRP to CWP (10%), and (5) persistent CWP (6%). Age, sleeping problems, poor vitality, and physical function at baseline were associated with pain progression from NCP. Female gender, seeking care for pain, lack of social support, poor physical function, vitality, and mental health predicted poor pain prognosis among those with CRP. In conclusion, chronic pain was common in the population including 6% reporting persistent CWP, although the majority persistently reported NCP. Most people had stable pain status, but some had ongoing change in pain status over time including people who improved from chronic pain. It was possible to identify clinically relevant factors, characterizing trajectories of chronic pain development, that can be useful for identifying individuals at risk and potential targets for intervention.

Psycho-sensory relationships in chronic pain

BACKGROUND

Psychological variables contribute to pain- and injury-related outcomes. We examined the hypothesis that anatomical spread and intensity of persistent pain relate to anxiety-related variables: generalised anxiety, fear of pain and pain catastrophising.

METHODS

An online survey was used to gather data from 413 women with persistent pain (low back pain, n = 139; fibromyalgia syndrome, n = 95; neck pain, n = 55; whiplash, n = 41; rheumatoid arthritis, n = 37; migraine, n = 46). The spread and intensity of pain were assessed using the McGill pain chart and a Numerical Rating Scale. A Bayesian Structural Equation Model assessed if the intensity and spread of pain increased with anxiety-related variables. Men were also surveyed (n = 80), but the sample size was only sufficient for analysing if their data were consistent with the model for women.

RESULTS

Across subgroups of women, one standard deviation increase in catastrophising, generalised anxiety and fear corresponded to 27%, 7% and -1% additional pain areas and a 1.1, 0 and -0.1 change in pain intensity (on 0-10 scale), respectively. Overall, our clinical significance criterion - a 30% shift in pain variable in relation to one standard deviation increase in psychological variable - was not met. However, in subgroups it was met for pain spread (low back pain, neck pain and migraine) and pain intensity (migraine and neck pain) in relation to pain catastrophising. The model generally had low goodness-of-fit to men.

CONCLUSION

These data support a meaningful relationship between some anxiety-related variables and pain in women for some conditions. Since the model did not consistently fit the men, we may conclude that the relationships are moderated by sex. Clinician attention to psychological variables as potential contributing factors can be justified; however, research is needed to understand the relationship and whether psychological treatment can reduce pain.

Differences in physical symptoms between those with and without kidney disease: a comparative study across disease stages in a UK population

BACKGROUND

Those living with kidney disease (KD) report extensive symptom burden. However, research into how symptoms change across stages is limited. The aims of this study were to 1) describe symptom burden across disease trajectory, and 2) to explore whether symptom burden is unique to KD when compared to a non-KD population.

METHODS

Participants aged > 18 years with a known diagnosis of KD (including haemodialysis (HD) and peritoneal dialysis (PD)) and with a kidney transplant) completed the Leicester Kidney Symptom Questionnaire (KSQ). A non-KD group was recruited as a comparative group. Multinominal logistic regression modelling was used to test the difference in likelihood of those with KD reporting each symptom.

RESULTS

In total, 2279 participants were included in the final analysis (age 56.0 (17.8) years, 48% male). The main findings can be summarised as: 1) the number of symptoms increases as KD severity progresses; 2) those with early stage KD have a comparable number of symptoms to those without KD; 3) apart from those receiving PD, the most frequently reported symptom across every other group, including the non-KD group, was 'feeling tired'; and 4) being female independently increased the likelihood of reporting more symptoms.

CONCLUSIONS

Our findings have important implications for patients with KD. We have shown that high symptom burden is prevalent across the spectrum of disease, and present novel data on symptoms experienced in those without KD. Symptoms requiring the most immediate attention given their high prevalence may include pain and fatigue.

TRIAL REGISTRATION

The study was registered prospectively as ISRCTN11596292 .

Serotonergic Neurotransmission System Modulator, Vortioxetine, and Dopaminergic D2/D3 Receptor Agonist, Ropinirole, Attenuate Fibromyalgia-Like Symptoms in Mice

Fibromyalgia is a disease characterized by lowered pain threshold, mood disorders, and decreased muscular strength. It results from a complex dysfunction of the nervous system and due to unknown etiology, its diagnosis, treatment, and prevention are a serious challenge for contemporary medicine. Impaired serotonergic and dopaminergic neurotransmission are regarded as key factors contributing to fibromyalgia. The present research assessed the effect of serotonergic and dopaminergic system modulators (vortioxetine and ropinirole, respectively) on the pain threshold, depressive-like behavior, anxiety, and motor functions of mice with fibromyalgia-like symptoms induced by subcutaneous reserpine (0.25 mg/kg). By depleting serotonin and dopamine in the mouse brain, reserpine induced symptoms of human fibromyalgia. Intraperitoneal administration of vortioxetine and ropinirole at the dose of 10 mg/kg alleviated tactile allodynia. At 5 and 10 mg/kg ropinirole showed antidepressant-like properties, while vortioxetine had anxiolytic-like properties. None of these drugs influenced muscle strength but reserpine reduced locomotor activity of mice. Concluding, in the mouse model of fibromyalgia vortioxetine and ropinirole markedly reduced pain. These drugs affected emotional processes of mice in a distinct manner. Hence, these two repurposed drugs should be considered as potential drug candidates for fibromyalgia. The selection of a specific drug should depend on patient’s key symptoms.

EQ-5D-5L Population Norms and Health Inequality in Colombia

OBJECTIVES

The EQ-5D-3L and EQ-5D-5L instruments have been used in studies of patient and demographic groups in Colombia, but to date there are no 5L population norms. This study aimed to produce a set of EQ-5D-5L population norms for Colombia and to see what insights into health inequality in Colombia can be discerned from these norms.

METHODS

The EQ-5D-5L self-reported health questionnaire was included in a survey of a representative sample of 3400 adults aged 18 to 64 in Colombia. EQ-5D-5L states, mean EQ VAS, and index values were obtained by sex, age, education, income group, ethnicity, residence, employment status, health insurance status, and household size. EQ-5D-5L index values from Uruguay were used. Regression models were used to investigate inequality.

RESULTS

The mean EQ VAS value was 85.3, the mean index value was 0.953, and 52.2% of the sample reported being in state 11111. Self-reported health was higher for men, declined in higher age groups, and was lower for lower-income and education groups. The EQ-5D-5L instrument was observed to be more sensitive than the EQ-5D-3L instrument in Colombia. The dimensions with the highest prevalence of reported problems were anxiety/depression and pain/discomfort. The main drivers of inequality were age, sex, income, and education.

CONCLUSIONS

The population norms developed in this study can be used as baseline values for future studies of patient or treatment groups, and for investigations into the health of specific demographic groups.

Different Alternatives to Assess the Burden of Disease Using Attributable Fraction on a Disability Variable: The Case of Pain and Chronic Musculoskeletal Disorders in Chile

OBJECTIVES

To estimate the burden of disease through 4 complementary procedures to years lived with disability (YLDs) using the concept of attributable fraction and including analysis of subdomains of disability.

METHODS

We explored the burden on disability for 7 common musculoskeletal disorders (CMD) using the 2009 to 2010 Chilean National Health Survey, which included the Community Oriented Programme for the Control of Rheumatic Disease Core Questionnaire to identify cases with CMD, and an 8-domain questionnaire for health state descriptions. We calculated the proportion of disability attributable to pain in the general population and people with CMD. We also estimated the burden of CMD expressed as YLD and as the proportion of the disability in the general population attributable to people with CMD, with a particular focus in the pain domain of disability. Second order of uncertainty around point estimations was also characterized.

RESULTS

Pain domain of disability accounted for 23.4% of the total disability in the general population, and between 20% (fibromyalgia) to 27.1% (osteoarthritis of the hip) in people with some of the selected CMD. People with chronic musculoskeletal pain accounted for 21.2% of total disability from general population, which generated 1.2 million of YLD (6679 YLD/100 000 inhabitants). Chronic low back pain and osteoarthritis of the knee were in the top position of specific CMDs, explaining the highest national burden.

CONCLUSION

Pain is an essential component of disability in people with CMD and also in the general population. The approach used can be easily applied to other health conditions and other domains of disability.

EQ-5D self-reported health in Barbados and Jamaica with EQ-5D-5L population norms for the English-speaking Caribbean

Background

The EQ-5D instrument is increasingly used in clinical and resource allocation decision making in developed and developing countries. EQ-5D valuation and population norms studies have been undertaken for Trinidad and Tobago, however no population norms or value sets have been generated for the other Caribbean countries. The aims of this study were to provide population norms for Barbados and Jamaica, and to develop a set of population norms that could be used by the other English-speaking Caribbean countries.

Methods

The EQ-5D-5L self-reported health questionnaire was included in surveys of representative samples of adults in Barbados and adults in Jamaica in 2013. EQ-5D health states, mean EQ VAS scores and mean EQ-5D-5L index values (using the Trinidad and Tobago value set) were calculated for demographic groups in both countries based on 2347 respondents from Barbados and 1423 from Jamaica. A set of ‘Caribbean’ norms were developed by combining the Barbados and Jamaica data with norms recently published for Trinidad and Tobago.

Results

Data were obtained for 2347 and 1423 respondents in Barbados and Jamaica respectively. The mean index and EQ VAS values were 0.943 and 81.9 for Barbados, and 0.948 and 87.8 for Jamaica. The health states most commonly observed in the two countries were similar. Generally the demographic patterns of self-reported health were consistent with those found in other studies. Some differences between the countries were observed in the patterns of rates of reporting problems on the EQ-5D dimensions among age-gender groups specifically for anxiety/depression and pain/discomfort

Conclusion

This study has produced a set of EQ-5D population norms that can be used as base-line values in clinical and clinico-economic analyses for Barbados and Jamaica and for the English-Speaking Caribbean region.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12955-021-01734-8.

The Prevalence and Factors Associated with Musculoskeletal Pain Among Pilgrims During the Hajj

Background

Musculoskeletal pain is a primary burden on individuals as well as social and health care systems. Annually, 2-3 million pilgrims perform the Hajj in Mecca, Saudi Arabia. The Hajj is highly physically demanding because pilgrims generally move by foot for long distances among a series of religious sites, an effort that may exceed their typical levels of physical activity. To understand the impact of musculoskeletal pain on the completion of the Hajj, it is first necessary to evaluate the extent of the problem. Accordingly, this study aimed to estimate the prevalence of musculoskeletal pain and associated factors among pilgrims during the Hajj.

Methods

A cross-sectional survey was conducted during the period of the Hajj. The participants were adult pilgrims ≥ 18 years of age. Data regarding demographics, the prevalence of falls and the point prevalence of musculoskeletal pain by anatomical site were recorded. Participants were allowed to report more than one site of pain. Prevalence, crude and adjusted risk ratios were calculated.

Results

A total of 1715 pilgrims were included in the analysis. The prevalence of falls was 13.76%. The prevalence of overall musculoskeletal pain (pain at any site) was 80.46%. Musculoskeletal pain was most commonly reported in the ankle/foot (38.34%), leg (29.89%), lower back (28.47%) and knee (21.84%). In general, musculoskeletal pain at multiple sites was more common in females and in older and obese individuals. However, there were variations in the importance of sex, age and body mass index as associated factors across different pain sites.

Conclusion

Musculoskeletal pain is common among pilgrims. Unlike most populations examined in other studies, ankle/foot pain was the most common in pilgrims. These data provide guidance for potential preventative programs and the allocation of resources to optimize pilgrims' experiences and ability to complete the Hajj.

Associations between socioeconomic deprivation and pharmaceutical prescribing in primary care in England

BACKGROUND

Socioeconomic deprivation is associated with health inequality. Previous studies have described associations between primary care prescribing rates and deprivation for individual drugs or drug classes. We explore the correlation between socioeconomic deprivation and the rate of prescribing of individual pharmaceutical drugs, and drug classes, in primary care in England, to identify prescribing inequalities that would require further investigation.

METHODS

In this cross-sectional study, national primary care prescribing data, by primary care practice, were retrieved for the calendar year 2019 in England. Socioeconomic deprivation was quantified using the Index of Multiple Deprivation (IMD) score. Correlations were calculated using Spearman's rank correlation coefficient (ρ), adjusting for practice list size and demographics, with a Bonferroni-corrected p value threshold of 5×10^-5.

RESULTS

We included 1.05 billion prescription items dispensed from 6896 England practices. 142/206 (69%) drug classes and 505/774 (65%) drugs were significantly correlated with IMD score (p<5×10^-5). Of the 774 included drugs, 31 (4%) were moderately positively associated with IMD score (ρ>0.4). Only one was moderately negatively correlated with IMD score (ρ<-0.4), suggesting higher prescribing rates in more affluent areas. The drug classes most strongly associated with IMD score included opioid and non-opioid analgesics, antipsychotics and reflux medications. Drug classes most strongly associated with affluence included epinephrine, combined oral contraceptives and hormone replacement therapy.

CONCLUSION

We identify novel associations of prescribing with deprivation. Further work is required to identify the underlying reasons for these associations so that appropriate interventions can be formulated to address drivers of inequality.

Assessing the benefits on quality of life of a multicomponent intervention for fibromyalgia syndrome in primary care: patients' and health professionals' appraisals: a qualitative study protocol

INTRODUCTION

Fibromyalgia syndrome (FMS) is a complex condition still scarcely understood and with ambiguity when prescribing treatment. Both patients and healthcare providers can supply valuable information for the development of new treatment strategies. The qualitative narrative analysis of participant's accounts is potentially helpful to reveal new insights about their opinions, needs, and experiences and, consequently, to model healthcare interventions accurately. International treatment guidelines suggest a promising future for multicomponent intervention (MI) approaches for FMS. This study aims to assess the benefits of a MI for patients with FMS in the context of primary care (PC) in Terres de L'Ebre, Catalonia (Spain). Furthermore, it is intended to detect the overall perception of effectiveness and to understand patients' lived experience and its impact on the quality of life.

METHOD AND ANALYSIS

Qualitative research from a socioconstructivism paradigm perspective and a Hermeneutic Phenomenological method. For data collection, four focus group discussions (FGDs) of 8-12 people (2 FGDs of patients and 2 of professionals) and 10-12 key informant interviews with the participants in the MI group will be carried out. All the information will be recorded and verbatim transcribed to perform an interpretive thematic analysis.

ETHICS AND DISSEMINATION

This study protocol has been approved by the Clinical Research Ethics Committee from the IDIAPJGol Institute, on 25 April 2018 (code P18/068), according to the Declaration of Helsinki/Tokyo. All participants will receive oral/written information about the study, and they will be required to sign an informed consent sheet. Data anonymity will be guaranteed. Dissemination will be carried out through publications in scientific journals, presentations in academic meetings, workshops and through the local and national media.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT04049006; Pre-results.

The antinuclear antibody dense fine speckled pattern and possible clinical associations: An indication of a proinflammatory microenvironment

BACKGROUND

Indirect immunofluorescence (IIF) is the most prevalent screening antinuclear antibody test for systemic autoimmune rheumatic disease (SARD). Certain IIF patterns have known antibody and disease associations, but the dense fine speckled (ANA-DFS) pattern has no confirmed clinical associations. Our objective was to determine the prevalence of SARD among a group of ANA-DFS positive individuals and to identify final diagnoses among non-SARD individuals in order to determine possible clinical associations with the ANA-DFS pattern.

METHODS

A retrospective study of 425 patients from a university health care system with a positive ANA-DFS pattern consecutively between August 2017 and September 2018. Sera samples underwent ANA testing by IIF on HEp-2 cell substrates (Euroimmun, Germany). Clinical information was retrieved from electronic health records and stored in a de-identified database.

RESULTS

The prevalence of SARD was 24%. Undetermined diagnosis (17%), skin disorders (12.1%), and fibromyalgia/chronic pain syndrome/chronic fatigue syndrome (11.8%) were the most common non-SARD diagnoses. Taking into account past medical history, the most common non-SARD were atopic disorders (21.2%), fibromyalgia/chronic pain syndrome/chronic fatigue syndrome (17.6%), and skin disorders (16.7%).

CONCLUSIONS

The ANA-DFS pattern may be indicative of an underlying antigen-antibody interaction that plays a role in either the initiation or propagation of immunologic reactions. DFS70/LEDGF is a transcription factor involved in cell survival and stress protection, and autoantibodies may inhibit its function. It is likely that there are other antibodies producing the ANA-DFS pattern besides anti-DFS70/LEDGF, and more research is necessary to identify additional antibody specificities. The ANA-DFS pattern may be an indicator of a proinflammatory microenvironment given the high frequency of symptomatic patients and disease processes with an immunologic basis (including SARD).

Widespread pain is a risk factor for cardiovascular mortality: results from the Framingham Heart Study

AIMS

With the introduction of widespread pain (WSP) as a separate diagnostic code in the ICD-11, WSP has now become an own clinical diagnosis independent of the underlying pathophysiology. Research has reported aetiological associations of WSP and cardiovascular diseases. However, studies on mortality risk in individuals with WSP have reported inconsistent results. This study investigates whether there is increased mortality in WSP individuals and establish potential determinants of mortality risk. Therefore, we evaluates the population-based prospective cohort of the Framingham Heart Study (FHS).

METHODS AND RESULTS

The FHS is a longitudinal multi-generational study. Pain status was assessed uniquely between 1990 and 1994. Cox proportional hazards modelling was used to estimate hazard ratios (HRs) of WSP on all-cause mortality controlling for sex and age, cardiovascular risk factors, cancer history, lifestyle factors and current medication. WSP examination was carried out in 4746 participants of the FHS (60.3 ± 13.5 years, 55.1% women). A total of 678 (14.5%) subjects fulfilled the criteria for WSP, whereas 4011 (85.5%) subjects did not. The follow-up time was 15 years, during which 202 persons died in the WSP group and 1144 in the no-WSP group. When adjusting for age and sex, all-cause mortality was increased by about 16% in WSP subjects. Individuals with WSP had an increased HR particularly for cardiovascular cause of death (HR adjusted by age and sex = 1.46, 95% confidence interval 1.10-1.94).

CONCLUSION

Our data show that in a large population-based cohort, WSP is associated with increased HR for cardiovascular cause of death, underlining the need for pain assessments in cardiovascular practice.

Significant correlation between plasma proteome profile and pain intensity, sensitivity, and psychological distress in women with fibromyalgia

Fibromyalgia (FM) is a complex pain condition where the pathophysiological and molecular mechanisms are not fully elucidated. The primary aim of this study was to investigate the plasma proteome profile in women with FM compared to controls. The secondary aim was to investigate if plasma protein patterns correlate with the clinical variables pain intensity, sensitivity, and psychological distress. Clinical variables/background data were retrieved through questionnaires. Pressure pain thresholds (PPT) were assessed using an algometer. The plasma proteome profile of FM (n = 30) and controls (n = 32) was analyzed using two-dimensional gel electrophoresis and mass spectrometry. Quantified proteins were analyzed regarding group differences, and correlations to clinical parameters in FM, using multivariate statistics. Clear significant differences between FM and controls were found in proteins involved in inflammatory, metabolic, and immunity processes. Pain intensity, PPT, and psychological distress in FM had associations with specific plasma proteins involved in blood coagulation, metabolic, inflammation and immunity processes. This study further confirms that systemic differences in protein expression exist in women with FM compared to controls and that altered levels of specific plasma proteins are associated with different clinical parameters.

The impact of chronic widespread pain on health status and long-term health predictors: a general population cohort study

Background

Chronic widespread pain (CWP) has a negative impact on health status, but results have varied regarding gender-related differences and reported health status. The aim was to study the impact of CWP on health status in women and men aged 35–54 years in a sample of the general population. The aim was further to investigate lifestyle-related predictors of better health status in those with CWP in a 12- and 21-year perspective.

Method

A general population cohort study including 975 participants aged 35–54 years, with a 12- and 21-year follow-up. CWP was measured with a pain mannequin, and the questionnaire included questions on lifestyles factors with SF-36 for measurement of health status. Differences in health status were analysed with independent samples t-test and health predictors with logistic regression analysis.

Results

The prevalence of CWP was higher in women at all time points, but health status was reduced in both women and men with CWP (p < 0.001) with no gender differences of clinical relevance. At the 12-year follow-up, a higher proportion of women than men had developed CWP (OR 2.04; CI 1.27–3.26), and at the 21-year follow-up, a higher proportion of men had recovered from CWP (OR 3.79; CI 1.00–14.33). In those reporting CWP at baseline, a better SF-36 health status (Physical Functioning, Vitality or Mental Health) at the 12-year follow-up was predicted by male gender, having personal support, being a former smoker, and having no sleeping problems. In the 21-year follow-up, predictors of better health were male gender, a weekly intake of alcohol, and having no sleeping problems.

Conclusion

Women and men with CWP have the same worsening of health status, but men recover from CWP to a greater extent in the long-term. Being male, having social support, being a former smoker, and having no sleeping problems were associated with better health status in those with CWP.

Effectiveness of a multicomponent treatment versus conventional treatment in patients with fibromyalgia: Study protocol

BACKGROUND

Fibromyalgia (FM) is a chronic pain syndrome characterized by widespread musculoskeletal pain and multiple symptoms. It is a common clinical condition whose etiology is unclear. Currently, there is no gold standard treatment for FM. Management of this condition is therefore aimed at reducing symptoms and maintaining the individual's ability to function optimally. Based on the principal symptoms and characteristics of individuals with FM, we hypothesized that the implementation of a multicomponent treatment (with physical exercise, cognitive behavioral therapy adding to a graded motor imagery program, and therapeutic neuroscience education) would be more effective than conventional treatment in women with FM. This paper describes the rationale and methods of study intended to test the effectiveness of multicomponent treatment versus conventional treatment in patients with FM.

METHOD/DESIGN

Fifty-six female individuals between 18 and 65 years of age, who were referred to the physical therapy department of the Rehabilitar Center in Chile, will be randomized into two treatment arms. The intervention group will receive a multicomponent treatment program for duration of 12 weeks. The control group will receive a conventional treatment for this condition for 12 weeks. The primary outcome measure will be the pain intensity score, measured by the numeric pain rating scale (NPRS), and the secondary outcomes will be the FM Impact Questionnaire (FIQ), and affective components of pain, such as catastrophizing using the Pain Catastrophizing Scale (PCS), fear of movement using the Tampa Scale Kinesiophobia (TSK), and sleep quality as measured by the Pittsburgh Sleep Quality Index (PSQI).

DISCUSSION

This paper reports the design of a randomized clinical trial aimed at assessing the effectiveness of the multicomponent treatment versus conventional treatment in women with FM.

TRIAL REGISTRATION

Brazilian registry of clinical trials UTN number U1111-1232-0862. Registered 22 April 2019.

No evidence for altered plasma NGF and BDNF levels in fibromyalgia patients

There has been a surging interest in the putative role of peripheral growth factors in the pathophysiology of fibromyalgia, specifically in the peripheral sensitization that occurs in chronic pain disorders. This cross-sectional study set out to assess and compare brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in plasma samples from fibromyalgia patients and healthy controls. Plasma BDNF and NGF were measured in 89 fibromyalgia patients and 36 pain-free controls, and compared using ANCOVA controlling for potential confounders, as well as Bayesian methods for parameter estimation and model evaluation. BDNF and NGF levels in fibromyalgia patients did not differ from those in pain-free controls. Statistical methods were consistent, with both frequentist and Bayesian approaches leading to the same conclusions. Our study fails to replicate the finding that peripheral BDNF is altered in fibromyalgia, and instead our findings suggest that plasma levels of growth factor appear normative in fibromyalgia.

The joint effect of insomnia symptoms and lifestyle factors on risk of self-reported fibromyalgia in women: longitudinal data from the HUNT Study

OBJECTIVES

To investigate the association between insomnia symptoms and risk of self-reported fibromyalgia in women, and to explore whether leisure time physical activity and body mass index (BMI) modify this association.

DESIGN

Prospective cohort study.

SETTING

We used longitudinal data from the Norwegian Nord-Trøndelag Health Study collected in 1995-1997 (baseline) and 2006-2008 (follow-up).

PARTICIPANTS

A total of 14 172 women who reported to be free from fibromyalgia at baseline.

PRIMARY OUTCOME MEASURES

We estimated adjusted risk ratios (RRs) with 95% CI for self-reported fibromyalgia at follow-up associated with baseline insomnia symptoms, leisure time physical activity and BMI.

RESULTS

Overall, 466 incident cases of fibromyalgia were reported during the follow-up period of approximately 11 years, corresponding to a crude absolute risk (AR) of 3.3%. Compared with women without insomnia symptoms (crude AR=2.8%), women who reported one, two or three symptoms had RRs of fibromyalgia of 1.39 (95% CI: 1.08 to 1.80), 1.86 (95% CI: 1.33 to 2.59) and 2.66 (95% CI: 1.75 to 4.06), respectively. Compared with highly physically active women without insomnia symptoms (crude AR=2.7%), women with one or more insomnia symptoms had a RR of fibromyalgia of 1.90 (95% CI: 1.30 to 2.79) if they reported low physical activity and a RR of 1.55 (95% CI: 1.12 to 2.13) if they reported high physical activity. We found no synergistic effect between insomnia symptoms and BMI on risk of fibromyalgia; however, overweight and obese women with one or more insomnia symptoms had RRs of 2.35 (95% CI: 1.73 to 3.21) and 2.18 (95% CI: 1.42 to 3.35) compared with the reference group of normal weight women without insomnia symptoms (crude AR=2.3%).

CONCLUSIONS

Insomnia symptoms are strongly and positively associated with risk of fibromyalgia in adult women. Leisure time physical activity may compensate for some of the adverse effect of insomnia symptoms on risk of fibromyalgia.

Eye Pain and Dry Eye in Patients with Fibromyalgia

Objectives

The aim of this study was to examine visual function and eye symptoms in fibromyalgia patients, with a particular focus on dry eye syndrome and eye pain.

Methods

A tertiary care center-based cross-sectional study was carried out in chronic musculoskeletal pain patients diagnosed with fibromyalgia. Chronic musculoskeletal pain patients without fibromyalgia were enrolled as a comparison group. Self-reported eye pain was investigated with the McGill pain questionnaire and the numeric rating scale. In addition, we assessed corrected visual acuity, vision-related quality of life, and self-reported dry eye syndrome.

Results

A total of 90 musculoskeletal pain patients were included, with 66 patients fulfilling American College of Rheumatology 1990 criteria for fibromyalgia. Sixty-seven percent (95% confidence interval [CI] = 56%-78%) of the fibromyalgia patients reported eye pain, and 62% (95% CI = 43%-81%) of those were without fibromyalgia diagnosis. Sixty-seven percent (95% CI = 56%-78%) of the fibromyalgia patients reported an experience of dry eye compared with 76% (95% CI = 57%-95%) in the nonfibromyalgia group. Vision-related quality of life was noticeably reduced in both groups.

Conclusions

Eye pain and dry eye are common in chronic pain patients, with comparable prevalence in musculoskeletal pain patients with and without fibromyalgia.

Stress levels predict substantial improvement in pain intensity after 10 to 12 years in women with fibromyalgia and chronic widespread pain: a cohort study

Background

Previous studies of prognosis for women with Fibromyalgia (FM) or chronic widespread pain (CWP) show contradictory results. However, some women appear to improve in pain and other core symptoms over time. There is limited knowledge about predictors of substantial improvement in pain intensity over a longer period of time. The primary objective of this study was to investigate the natural course of pain intensity and distribution of pain over 10 to 12 years in a cohort of 166 women with FM or CWP. Secondarily we wanted to investigate predictors of substantial improvement (≥50%) in pain intensity after 10 to 12 years.

Methods

The study is a longitudinal prospective cohort study. 166 women with FM or CWP were followed up after 10 to 12 years. 126 women (76%) participated in the follow-up and completed a battery of questionnaires concerning pain intensity, pain distribution and other physical and mental aspects of health. Differences in symptoms within the cohort over 10 to 12 years and predictors of substantial improvement (≥50%) in pain intensity were calculated.

Results

Pain had improved at the 10 to 12 year follow-up (p < 0.001) with a mean change of − 9.2 mm (SD 23.3, 95% CI: − 13.3; − 5.0) for pain intensity and − 2.0 sites (SD 4.2, 95% CI: − 2.7; − 1.2) for pain distribution. Nine percent of the 126 women showed an individual moderate improvement in pain intensity while 16% showed a substantial improvement at the follow-up as compared to baseline. Lower symptoms of stress and higher pain intensity at baseline predicted higher probability of reporting at least 50% less pain intensity after 10 to 12 years as compared to baseline.

Conclusions

A majority of women with FM and CWP appear to have a positive course of pain over time, which should be communicated to these patients in health care. Reducing stress levels might contribute to better chances of improvement over time.

Trial registration

Clinicaltrials.gov NCT02872129, registered 06/30/2016.

Clinical significance of anti-dense fine speckled 70 antibody in patients with fibromyalgia

BACKGROUND/AIMS

Fibromyalgia (FM) is a common rheumatologic disease characterized by chronic widespread pain, along with various clinical manifestations including atypical autoimmune characteristics. Despite its high prevalence, there remain no approved laboratory tests to identify specific manifestations of FM, or to rule out FM from other rheumatic diseases. Anti-dense fine speckled 70 (anti-DFS70) antibodies were initially identified as a form of anti-nuclear antibodies in a patient with interstitial cystitis. Anti-DFS70 antibodies are found in ≤ 10% of healthy individuals, but have suggestive negative association with autoimmune diseases; however, the clinical significance of these autoantibodies in FM patients remains poorly understood.

METHODS

We examined 39 patients with FM, along with 17 patients with systemic lupus erythematosus (SLE), and 19 healthy individuals (HI). Patients were compared based on physical measurements, disease duration, tender point counts, FM Impact Questionnaire (FIQ) scores, visual analog scale (VAS) for pain, somatic symptoms, and anti-DFS70 antibodies.

RESULTS

Levels of anti-DFS70 antibodies were significantly higher in the FM and HI groups than in those with SLE. Both anti-DFS70 antibodies and VAS scores were positively correlated with FM. Within the FM group, patients with arthralgia had higher anti-DFS70 antibody values compared to those without arthralgia (p = 0.024); antibody levels were also higher in patients with sleep disturbances relative to those without sleep issues (p = 0.024). In contrast, there were no correlations between anti-DFS70 antibodies and age, body mass index, disease duration, tender point counts, FIQ, short-form health survey results, or other clinical manifestations.

CONCLUSION

Anti-DFS70 antibodies may represent a useful biomarker for differentiating between FM and other autoimmune diseases. The levels of anti-DFS70 antibodies were also significantly higher among patients with arthralgia and sleep disturbances. Further investigations are necessary to evaluate the relationships between anti-DFS70 antibodies and other cytokines as a predictive marker for pain.

A critical overview of the current myofascial pain literature - February 2019

This edition of the overview of current myofascial pain literature features several interesting and important publications. From Australia, Braithwaite and colleagues completed an outstanding systematic review of blinding procedures used in dry needling (DN) studies. Other papers tackled the interrater reliability of the identification of trigger points (TrP), the presence of muscle hardness related to latent TrPs, pelvic floor examination techniques, and the links between TrPs, headaches and shoulder pain. Israeli researchers developed a theoretical model challenging the contributions of the Cinderella Hypothesis to the development of TrPs. As in almost all issues, we included many DN, injection and acupuncture studies, which continue to be the focus of researchers all over the world.

Health-Related Quality of Life among Chronic Opioid Users, Nonchronic Opioid Users, and Nonopioid Users with Chronic Noncancer Pain

OBJECTIVE

Evaluate the association between opioid therapy and health-related quality of life (HRQoL) in participants with chronic, noncancer pain (CNCP).

DATA SOURCES

Medical Expenditure Panel Survey Longitudinal, Medical Conditions, and Prescription Files.

STUDY DESIGN

Using a retrospective cohort study design, the Mental Health Component (MCS12) and Physical Health Component (PCS12) scores of the Short Form-12 Version 2 were assessed to measure mental and physical HRQoL.

DATA COLLECTION

Chronic, noncancer pain participants were classified as chronic, nonchronic, and nonopioid users. One-to-one propensity score matching was employed to match chronic opioid users to nonchronic opioid users plus nonchronic opioid users and chronic opioid users to nonopioid users.

PRINCIPAL FINDINGS

A total of 5,876 participants were identified. After matching, PCS12 was not significantly different between nonchronic versus nonopioid users (LSM Diff = -0.98, 95% CI: -2.07, 0.10), chronic versus nonopioid users (LSM Diff = -2.24, 95% CI: -4.58, 0.10), or chronic versus nonchronic opioid users (LSM Diff = -2.23, 95% CI: -4.53, 0.05). Similarly, MCS12 was not significantly different between nonchronic versus nonopioid users (LSM Diff = 0.76, 95% CI: -0.46, 1.98), chronic versus nonopioid users (LSM Diff = 1.08, 95% CI: -1.26, 3.42), or chronic versus nonchronic opioid users (LSM Diff = -0.57, 95% CI: -2.90, 1.77).

CONCLUSIONS

Clinicians should evaluate opioid use in participants with CNCP as opioid use is not correlated with better HRQoL.

Controlled, cross-sectional, multi-center study of physical capacity and associated factors in women with fibromyalgia

Background

Health and physical capacity are commonly associated with disease, age, and socioeconomic factors. The primary objective of this study was to investigate the degree to which physical capacity, defined as muscle strength and walking ability, is decreased in women with fibromyalgia (FM), as compared to healthy women, who are matched for age and level of education. The secondary aim was to investigate whether muscle strength and walking ability are associated with age, symptom duration, activity limitations and, Body Mass Index (BMI) in women with FM and control subjects.

Methods

This controlled, cross-sectional, multi-center study comprised 118 women with FM and 93 age- and education-level-matched healthy women. The outcome measures were isometric knee-extension force, isometric elbow-flexion force, isometric hand-grip force, and walking ability. Differences between the groups were calculated, and for the women with FM analyses of correlations between the measures of physical capacity and variables were performed.

Results

The women with FM showed 20% (p < 0.001) lower isometric knee-extension force, 36% (p < 0.001) lower isometric elbow-flexion force, 34% (p < 0.001) lower isometric hand-grip force, and 16% lower walking ability (p < 0.001), as compared to the healthy controls. All measures of muscle strength in women with FM showed significant weak to moderate relationship to symptom duration (r_s = − 0.23–0.32) and walking ability (r_s = 0.25–0.36). Isometric knee-extension force correlated with activity limitations, as measured using the SF-36 Physical function subscale (r_s=0.23, p = 0.011).

Conclusions

Physical capacity was considerably decreased in the women with FM, as compared to the age- and education-level-matched control group. All measures of physical capacity showed a significant association with symptom duration. Knee-extension force and walking ability were significantly associated with activity limitations, age, and BMI. It seems important to address this problem and to target interventions to prevent decline in muscle strength. Assessments of muscle strength and walking ability are easy to administer and should be routinely carried out in the clinical setting for women with FM.

Trial registration

ClinicalTrials.gov identification number: NCT01226784, Oct 21, 2010.

Morning cortisol and fasting glucose are elevated in women with chronic widespread pain independent of comorbid restless legs syndrome

Background and aims:

Chronic widespread pain (CWP) is associated with poor quality of sleep, but the detailed underlying mechanisms are still not fully understood. In this study we investigated the influence of CWP on morning cortisol and fasting glucose concentrations as well as sleep disordered breathing.

Methods:

In this case-control study, subjects with CWP (n=31) and a control group without CWP (n=23) were randomly selected from a population-based cohort of women. Current pain intensity, sleep quality, excessive daytime sleepiness [Epworth sleepiness scale (ESS)], psychiatric comorbidity and occurrence of restless legs syndrome (RLS) were assessed. Overnight polygraphy was applied to quantify sleep apnoea, airflow limitation and attenuations of finger pulse wave amplitude (>50%) as a surrogate marker for increased skin sympathetic activity. Morning cortisol and fasting glucose concentrations were determined. Generalised linear models were used for multivariate analyses.

Results:

CWP was associated with higher cortisol (464±141 vs. 366±111 nmol/L, p=0.011) and fasting glucose (6.0±0.8 vs. 5.4±0.7 mmol/L, p=0.007) compared with controls. The significance remained after adjustment for age, body mass index, RLS and anxiety status (β=122±47 nmol/L and 0.89±0.28 mmol/L, p=0.009 and 0.001, respectively). The duration of flow limitation in sleep was longer (35±22 vs. 21±34 min, p=0.022), and pulse wave attenuation was more frequent (11±8 vs. 6±2 events/h, p=0.048) in CWP subjects compared with controls. RLS was associated with higher ESS independent of CWP (β=3.1±1.3, p=0.018).

Conclusions:

Elevated morning cortisol, impaired fasting glucose concentration and increased skin sympathetic activity during sleep suggested an activated adrenal medullary system in subjects with CWP, which was not influenced by comorbid RLS.

Implications:

CWP is associated with activated stress markers that may deteriorate sleep.

Combination pharmacotherapy for the treatment of fibromyalgia in adults

BACKGROUND

Fibromyalgia is a chronic widespread pain condition affecting millions of people worldwide. Current pharmacotherapies are often ineffective and poorly tolerated. Combining different agents could provide superior pain relief and possibly also fewer side effects.

OBJECTIVES

To assess the efficacy, safety, and tolerability of combination pharmacotherapy compared to monotherapy or placebo, or both, for the treatment of fibromyalgia pain in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to September 2017. We also searched reference lists of other reviews and trials registries.

SELECTION CRITERIA

Double-blind, randomised controlled trials comparing combinations of two or more drugs to placebo or other comparators, or both, for the treatment of fibromyalgia pain.

DATA COLLECTION AND ANALYSIS

From all studies, we extracted data on: participant-reported pain relief of 30% or 50% or greater; patient global impression of clinical change (PGIC) much or very much improved or very much improved; any other pain-related outcome of improvement; withdrawals (lack of efficacy, adverse events), participants experiencing any adverse event, serious adverse events, and specific adverse events (e.g. somnolence and dizziness). The primary comparison was between combination and one or all single-agent comparators. We also assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We identified 16 studies with 1474 participants. Three studies combined a non-steroidal anti-inflammatory drug (NSAID) with a benzodiazepine (306 participants); two combined amitriptyline with fluoxetine (89 participants); two combined amitriptyline with a different agent (92 participants); two combined melatonin with an antidepressant (164 participants); one combined carisoprodol, paracetamol (acetaminophen), and caffeine (58 participants); one combined tramadol and paracetamol (acetaminophen) (315 participants); one combined malic acid and magnesium (24 participants); one combined a monoamine oxidase inhibitor with 5-hydroxytryptophan (200 participants); and one combined pregabalin with duloxetine (41 participants). Six studies compared the combination of multiple agents with each component alone and with inactive placebo; three studies compared combination pharmacotherapy with each individual component but did not include an inactive placebo group; two studies compared the combination of two agents with only one of the agents alone; and three studies compared the combination of two or more agents only with inactive placebo.Heterogeneity among studies in terms of class of agents evaluated, specific combinations used, outcomes reported, and doses given prevented any meta-analysis. None of the combinations of drugs found provided sufficient data for analysis compared with placebo or other comparators for our preferred outcomes. We therefore provide a narrative description of results. There was no or inadequate evidence in any comparison for primary and secondary outcomes. Two studies only reported any primary outcomes of interest (patient-reported pain relief of 30%, or 50%, or greater). For each 'Risk of bias' item, only half or fewer of studies had unequivocal low risk of bias. Small size and selective reporting were common as high risk of bias.Our GRADE assessment was therefore very low for primary outcomes of pain relief of 30% or 50% or greater, PGIC much or very much improved or very much improved, any pain-related outcome, participants experiencing any adverse event, any serious adverse event, or withdrawing because of an adverse event.Three studies found some evidence that combination pharmacotherapy reduced pain compared to monotherapy; these trials tested three different combinations: melatonin and amitriptyline, fluoxetine and amitriptyline, and pregabalin and duloxetine. Adverse events experienced by participants were not serious, and where they were reported (in 12 out of 16 studies), all participants experienced them, regardless of treatment. Common adverse events were nausea, dizziness, somnolence, and headache.

AUTHORS' CONCLUSIONS

There are few, large, high-quality trials comparing combination pharmacotherapy with monotherapy for fibromyalgia, consequently limiting evidence to support or refute the use of combination pharmacotherapy for fibromyalgia.

Corneal sensitivity and subjective complaints of ocular pain in patients with fibromyalgia

PurposeFibromyalgia (FM) is a chronic pain disorder associated with pain and hypersensitivity in various parts of the body. The aim of this study was to understand whether changes in corneal sensitivity were associated with the subjective complaints of these patients.Patients and methodsIn this study, we included 36 patients with FM (30 female, 6 male, mean age: 46.7±9.2 years) and 39 healthy control subjects (33 females, 6 males, mean age: 44.3±7.6 years). We performed a detailed ophthalmological examination, measured tear film breakup time (TBUT), and performed Schirmer I test without anesthetic (SIT). Only patients that did not have any eye disease were included in this study. Subjective complaints of the patients were evaluated with ocular surface disease index (OSDI) scores and the corneal sensation was evaluated with Cochet-Bonnet esthesiometer.ResultsThere was no significant difference between the groups for age, sex, and visual acuity. Both SIT (16.1 mm vs 15.3 mm, P=0.36) and TBUT results (17.8 s vs 18.8 s, P=0.40) were similar in FM group and the controls subjects. However, corneal sensations in central (60.0 mm vs 55.0 mm, P=0.03), superior (57.5 mm vs 50.0 mm, P=0.005), and inferior (53.89 mm vs 46.03 mm, P<0.001) regions were significantly increased in FM patients. There was a significant positive correlation between corneal sensation and OSDI scores.ConclusionIn this study, we have demonstrated that the patients with FM have increased corneal sensitivity and have related ocular surface complaints similar to dry eye disease in the absence of it.

Joint pain within adult middle-aged women, attending a community clinic in a peri-urban area in South Africa: a cross-sectional survey

BACKGROUND

This study aimed to investigate the prevalence of joint pain in women between the ages of 40 and 64 years who attended a community clinic in the Free State to provide micro-information for health care planners.

METHODS

A sample of convenience was utilized in the cross-sectional survey. Health care workers were recruited to conduct the survey. Outcome measures included the Community-Oriented-Programme-For-The-Control-Of-Rheumatic-Disease questionnaire and European Quality of Life - 5 Dimensions health related quality of life measure. Descriptive statistics were calculated for categorical data and non-parametric tests for ordinal data. Quality Adjusted Life Years lost were based on the preference weights generated by the European Quality of Life - 5 Dimensions.

RESULTS

One thousand three hundred seventy-six participants were enrolled. The prevalence of joint pain experienced in either the short or the long term was 62.1% (CI 59.5-64.6%). The total number of Quality Adjusted Life Years lost in this sample was 41.4, that is a rate of 3008.7 (CI 2740-3310) per 100,000.

CONCLUSION

Epidemiological transition seems to be rapidly taking place in South Africa and the prevalence of joint pain is considerable. Primary health care systems should develop a cost-effective approach to manage and identify joint pain and improve the health-related quality of life of those living with this. Implications for Rehabilitation Prevalence of joint pain is considerable. Consume large amounts of health and social resources. A protocol for routine screening should be developed in community clinics. Cost-effective approach to manage joint pain should be identified to improve healthrelated quality of life of individuals living with joint pain.

Sex differences in primary muscle afferent sensitization following ischemia and reperfusion injury

BACKGROUND

Chronic pain conditions are more prevalent in women, but most preclinical studies into mechanisms of pain generation are performed using male animals. Furthermore, whereas group III and IV nociceptive muscle afferents provoke central sensitization more effectively than their cutaneous counterparts, less is known about this critical population of muscle nociceptors. Here, we compare the physiology of individual muscle afferents in uninjured males and females. We then characterize the molecular, physiological, and behavioral effects of transient ischemia and reperfusion injury (I/R), a model we have extensively studied in males and in females.

METHODS

Response properties and phenotypes to mechanical, thermal, and chemical stimulation were compared using an ex vivo muscle/nerve/dorsal root ganglia (DRG)/spinal cord recording preparation. Analyses of injury-related changes were also performed by assaying evoked and spontaneous pain-related behaviors, as well as mRNA expression of the affected muscle and DRGs. The appropriate analyses of variance and post hoc tests (with false discovery rate corrections when needed) were performed for each measure.

RESULTS

Females have more mechanically sensitive muscle afferents and show greater mechanical and thermal responsiveness than what is found in males. With I/R, both sexes show fewer cells responsive to an innocuous metabolite solution (ATP, lactic acid, and protons), and lower mechanical thresholds in individual afferents; however, females also possess altered thermal responsiveness, which may be related to sex-dependent changes in gene expression within the affected DRGs. Regardless, both sexes show similar increases in I/R-induced pain-like behaviors.

CONCLUSIONS

Here, we illustrate a unique phenomenon wherein discrete, sex-dependent mechanisms of primary muscle afferent sensitization after ischemic injury to the periphery may underlie similar behavioral changes between the sexes. Furthermore, although the group III and IV muscle afferents are fully developed functionally, the differential mechanisms of sensitization manifest prior to sexual maturity. Hence, this study illustrates the pressing need for further exploration of sex differences in afferent function throughout the lifespan for use in developing appropriately targeted pain therapies.

Peripheral Mechanisms of Ischemic Myalgia

Musculoskeletal pain due to ischemia is present in a variety of clinical conditions including peripheral vascular disease (PVD), sickle cell disease (SCD), complex regional pain syndrome (CRPS), and even fibromyalgia (FM). The clinical features associated with deep tissue ischemia are unique because although the subjective description of pain is common to other forms of myalgia, patients with ischemic muscle pain often respond poorly to conventional analgesic therapies. Moreover, these patients also display increased cardiovascular responses to muscle contraction, which often leads to exercise intolerance or exacerbation of underlying cardiovascular conditions. This suggests that the mechanisms of myalgia development and the role of altered cardiovascular function under conditions of ischemia may be distinct compared to other injuries/diseases of the muscles. It is widely accepted that group III and IV muscle afferents play an important role in the development of pain due to ischemia. These same muscle afferents also form the sensory component of the exercise pressor reflex (EPR), which is the increase in heart rate and blood pressure (BP) experienced after muscle contraction. Studies suggest that afferent sensitization after ischemia depends on interactions between purinergic (P2X and P2Y) receptors, transient receptor potential (TRP) channels, and acid sensing ion channels (ASICs) in individual populations of peripheral sensory neurons. Specific alterations in primary afferent function through these receptor mechanisms correlate with increased pain related behaviors and altered EPRs. Recent evidence suggests that factors within the muscles during ischemic conditions including upregulation of growth factors and cytokines, and microvascular changes may be linked to the overexpression of these different receptor molecules in the dorsal root ganglia (DRG) that in turn modulate pain and sympathetic reflexes. In this review article, we will discuss the peripheral mechanisms involved in the development of ischemic myalgia and the role that primary sensory neurons play in EPR modulation.

Anatomical Basis of the Myofascial Trigger Points of the Gluteus Maximus Muscle

Myofascial pain syndrome is characterized by pain and limited range of motion in joints and caused by muscular contracture related to dysfunctional motor end plates and myofascial trigger points (MTrPs). We aimed to observe the anatomical correlation between the clinically described MTrPs and the entry point of the branches of the inferior gluteal nerve into the gluteus maximus muscle. We dissected twenty gluteus maximus muscles from 10 human adult cadavers (5 males and 5 females). We measured the muscles and compiled the distribution of the nerve branches into each of the quadrants of the muscle. Statistical analysis was performed by using Student's t-test and Kruskal-Wallis tests. Although no difference was observed either for muscle measurements or for distribution of nerve branching among the subjects, the topography of MTrPs matched the anatomical location of the entry points into the muscle. Thus, anatomical substract of the MTrPs may be useful for a better understanding of the physiopathology of these disorders and provide basis for their surgical and clinical treatment.

Effectiveness of Therapeutic Exercise in Fibromyalgia Syndrome: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

OBJECTIVE

The aim of this study was to summarize evidence on the effectiveness of therapeutic exercise in Fibromyalgia Syndrome.

DESIGN

Studies retrieved from the Cochrane Plus, PEDro, and Pubmed databases were systematically reviewed. Randomized controlled trials and meta-analyses involving adults with fibromyalgia were included. The primary outcomes considered in this systematic review were pain, global well-being, symptoms of depression, and health-related quality of life.

RESULTS

Effects were summarized using standardized mean differences with 95% confidence intervals using a random effects model. This study provides strong evidence that physical exercise reduces pain (-1.11 [95% CI] -1.52; -0.71; overall effect p < 0.001), global well-being (-0.67 [95% CI] -0.89, -0.45; p < 0.001), and symptoms of depression (-0.40 [95% CI] -0.55, -0.24; p < 0.001) and that it improves both components of health-related quality of life (physical: 0.77 [95% CI] 0.47; 1.08; p < 0.001; mental: 0.49 [95% CI] 0.27; 0.71; p < 0.001).

CONCLUSIONS

This study concludes that aerobic and muscle strengthening exercises are the most effective way of reducing pain and improving global well-being in people with fibromyalgia and that stretching and aerobic exercises increase health-related quality of life. In addition, combined exercise produces the biggest beneficial effect on symptoms of depression.

Association between endothelin‑1 and fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is characterized by widespread chronic musculoskeletal pain, stiffness and pressure hyperalgesia at soft tissue tender points. Patients with FMS may exhibit a tendency towards cold extremities and cold‑induced vasospasm. Endothelin‑1 (EDN1) is a potent vasoconstrictor that is mainly produced by endothelial cells. The present study aimed to determine whether plasma expression levels avvnd single‑nucleotide polymorphism (SNP; rs1800541) of the EDN1 gene were associated with FMS and/or any of its clinical variables. Plasma EDN1 levels were assessed by ELISA, and SNP genotypes were determined using polymerase chain reaction‑high‑resolution melting curve analysis. Patients with the TG genotype and the G allele may have an elevated risk of FMS. In addition, patients with FMS with the TG genotype and/or T allele exhibited higher plasma EDN1 levels compared with healthy controls. EDN1 levels increased significantly in patients with FMS compared with normal controls. In addition, EDN1 SNP was found to be associated with susceptibility to FMS.

Combination Analgesic Development for Enhanced Clinical Efficacy (CADENCE Trial): Study Protocol for a Double-Blind, Randomized, Placebo-Controlled Crossover Trial of an Alpha-Lipoic Acid - Pregabalin Combination for the Treatment of Fibromyalgia Pain

Background

Fibromyalgia is a clinical disorder commonly presenting with chronic widespread pain as well as sleep disturbance, fatigue, depression, and cognitive dysfunction. There is an urgent need for treatment strategies that provide better pain relief and fewer adverse effects (AEs). Efforts to develop rational combinations of specific fibromyalgia treatments have demonstrated potential for measurable improvements in pain relief, quality of life, and health care utilization. More than half of fibromyalgia patients receive 2 or more analgesics but current combination use is based on limited evidence. As an early proof-of-concept project from the Canadian Institutes of Health Research–Strategy on Patient-Oriented Research Chronic Pain Network, this trial protocol is expected to advance the field by rigorously evaluating a new treatment combination for fibromyalgia.

Objective

We will test the hypothesis that analgesic combinations containing at least one nonsedating agent would be as safe but more effective than either monotherapy because of additive pain relief without increasing overall AEs. Pregabalin (PGB), a sedating anticonvulsant, is proven effective for fibromyalgia, and the antioxidant, alpha-lipoic acid (ALA), one of the only nonsedating systemic agents proven effective for neuropathic pain, is currently being evaluated in fibromyalgia. Thus, we will conduct a clinical trial to compare a PGB+ALA combination to each monotherapy for fibromyalgia.

Methods

Using a double-blind, double-dummy, crossover design, 54 adults with fibromyalgia will be randomly allocated to 1 of 6 sequences of treatment with PGB, ALA, and PGB+ALA combination. During each of 3 different treatment periods, participants will take 2 sets of capsules containing (1) ALA (or placebo) and (2) PGB (or placebo) for 31 days, followed by an 11-day taper/washout period. The primary outcome will be mean daily pain intensity (0 to 10 scale) at maximal tolerated doses (MTDs) during each period. Secondary outcomes, assessed at MTD, will include global improvement, adverse events, mood, and quality of life.

Results

This trial attained ethics approval March 6, 2017 (Queen’s University Health Sciences and Affiliated Teaching Hospitals Research Ethics Board protocol number ANAE-313-17), and recruitment is set to start in August 2017.

Conclusions

This trial will provide rigorous evidence comparing the efficacy of a PGB-ALA combination to PGB alone and ALA alone in the treatment of fibromyalgia.

Trial Registration

International Standard Randomized Controlled Trial Number ISRCTN14939460; https://www.isrctn.com/ ISRCTN1493946 (Archived by WebCite at http://www.webcitation.org/6sFqAjxkt)