Developments in the scientific and clinical understanding of fibromyalgia

Hyperbaric oxygen therapy vs. pharmacological intervention in adults with fibromyalgia related to childhood sexual abuse: prospective, randomized clinical trial

Fibromyalgia syndrome (FMS) is a chronic pain syndrome characterized by disruptions in pain processing within the central nervous system. It exhibits a high prevalence among patients with a history of traumatic experiences, notably childhood sexual abuse (CSA). This study compared the efficacy of hyperbaric oxygen therapy (HBOT) to the current pharmacological standard of care for individuals suffering from CSA-related FMS. Forty-eight participants diagnosed with FMS and a history of CSA were randomly assigned to either the HBOT group (60 sessions of 100% oxygen at 2 ATA for 90 min, with air breaks every 5 min) or the medication (MED) group (FDA-approved medications, Pregabalin and Duloxetine). The primary endpoint was the Fibromyalgia impact questionnaire (FIQ) score, while secondary endpoints encompassed emotional status and daily functioning questionnaires, as well as pain thresholds and conditioned pain modulation tests. Brain activity was evaluated through single photon emission computed tomography (SPECT). Results revealed a significant group-by-time interaction for the FIQ score favoring HBOT over MED (p < 0.001), with a large effect size (Cohen's d = - 1.27). Similar findings were observed in emotional symptoms and functional measures. SPECT imaging demonstrated an increase in activity in pre-frontal and temporal brain areas, which correlated with symptoms improvement. In conclusion, HBOT exhibited superior benefits over medications in terms of physical, functional, and emotional improvements among FMS patients with a history of CSA. This associated with increased activity in pre-frontal and temporal brain areas, highlighting the neuroplasticity effect of HBOT.

Effectiveness of Acceptance and Commitment Therapy in Central Pain Sensitization Syndromes: A Systematic Review

OBJECTIVES

Acceptance and commitment therapy (ACT) is considered by the American Psychological Association as an evidence-based treatment for a variety of disorders, including chronic pain. The main objective of the present systematic review was to determine the effectiveness of ACT in patients with central pain sensitization syndromes (CPSS).

METHODS

This systematic review was conducted according to the guidelines of the Cochrane Collaboration and PRISMA statements. The protocol was registered in advance in the Prospective Register of Systematic Reviews (PROSPERO) international database. The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The PubMed, Scopus, and Web of Science databases were searched.

RESULTS

The literature search identified 21 studies (including investigations of fibromyalgia syndrome, irritable bowel syndrome, and migraine) eligible for the systematic review. There were no studies regarding the effectiveness of ACT for chronic tension-type headache (CTTH), interstitial cystitis (IC), or temporomandibular disorder (TMD). The evaluation of ROB showed that 12 of the selected studies were of low quality, 5 were of moderate quality, and 4 were high quality. ACT reduces some clinical symptoms, such as anxiety, depression, and pain. This positive effect of ACT might be mediated by pain acceptance, psychological flexibility, optimism, self-efficacy, or adherence to values. ACT showed better results in comparison to non-intervention (e.g., "waiting list") conditions, as well as pharmacological and psychoeducational interventions. It is not entirely clear whether extended ACT treatments are more advantageous than briefer interventions.

CONCLUSIONS

There are few studies about the effectiveness of ACT on CPSS. However, ACT seems to reduce subjective CPSS symptoms and improve the health-related quality of life of these patients. The absence of studies on the effectiveness of ACT in CTTH, IC, and TMD, indicate the pressing need for further ACT studies in these CPSS.

The p38/MK2 Axis in Monocytes of Fibromyalgia Syndrome Patients: An Explorative Study

Background and Objectives: The aetiology and pathomechanism of fibromyalgia syndrome 12 (FMS) as one of chronic pain syndromes still need to be further elucidated. Mitogen-activated protein kinase (MAPK) pathway has been proposed as a novel approach in pain management. Since the major symptom of fibromyalgia syndrome (FMS) patients is pain, it became of interest whether MAPK pathways, such as the stress-activated p38 MAPK/MK2 axis, are activated in FMS patients. Therefore, this study aimed at determining p38 MAPK/MK2 in FMS patients. Materials and Methods: Phosphorylation of MAPK-activated protein kinases 2 (MK2), a direct target of p38 MAPK, was measured in monocytes of FMS and healthy controls (HCs) to monitor the activity of this pathway. Results: The mean level of phosphorylated MK2 was fivefold higher in FMS patients as compared to HCs (p < 0.001). Subgroup analysis revealed that antidepressants did not influence the activity of MK2 in FMS patients. Conclusions: This result indicates that the p38/MK2 pathway could be involved in the pathomechanism of FMS, could act as a clinical marker for FMS, and could be a possible target for pain management in FMS patients.

Comparison of Beta-2 Adrenergic Receptor Gene Polymorphisms Between Patients with Fibromyalgia Syndrome and Healthy Controls

Objectives

This study aims to compare the beta-2 adrenergic receptor (ADRB2) gene polymorphisms of patients with fibromyalgia syndrome (FMS) with those of healthy control subjects, and to investigate the possible relationship between symptoms of FMS and polymorphisms of the ADRB2 gene.

Patients and methods

The study included 170 females (mean age 47.8±10.3 years; range, 21 to 75 years) diagnosed with FMS according to the 2010 American College of Rheumatology criteria and 170 healthy females (mean age 47.2±8.8 years; range, 20 to 72 years) as the control group. Several clinical symptoms of the participants related to FMS were questioned and recorded. The visual analog scale (VAS) and Fibromyalgia Impact Questionnaire (FIQ) scores of the fibromyalgia group were recorded. In both groups, the ADRB2 (rs1042717) single-nucleotide polymorphism was detected by way of a real-time polymerase chain reaction. The wild-type (Guanine/Guanine), the mutant type (Adenine/Adenine) and heterozygous type (Adenine/Guanine) were detected. The sample power was calculated considering the minor allele frequency.

Results

The comparison of the ADRB2 gene polymorphism between patients with FMS and the control subjects showed that the groups were similar in terms of ADBR2 gene polymorphism and genotype (p>0.05). There was no significant difference in terms of genotype when the ADRB2 gene polymorphisms in patients with FMS were compared in terms of clinical symptoms, VAS and FIQ scores (p>0.05).

Conclusion

Beta-2 adrenergic receptor (rs1042717) gene polymorphisms and genotype distribution are no different between patients with FMS and healthy individuals. ADRB2 gene polymorphisms in patients with FMS have no effect on clinical symptoms and VAS and FIQ scores. The results of the present study will light the way for future research into ADRB2 gene polymorphisms in the pathogenesis of FMS.

Lower limb muscle strength and serotonin receptor gene polymorphism as factors associated in women with fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a chronic pain syndrome characterized by generalized skeletal muscle chronic pain. Its etiology is not well defined, because there are several factors that may trigger it such as physical and/or emotional stresses, or a genetic susceptibility, involving serotonergic, dopaminergic and catecholaminergic paths. The objective of this study was to investigate the association between the strength of the lower limb, genetic polymorphism of the serotonin receptor gene HTR_2A in women with fibromyalgia.

METHODS

In this observational study of case-control type 48 women were evaluated who belonged to the group with FM (52 ± 12 years) and 100 women in the control group (58 ± 11 years). Socio demographic and anthropometric data were collected and peripheral blood samples for DNA extraction; genotypic analyzes were performed by means of PCR in real time by TaqMan® system. The lower limb muscle strength was assessed through the test of sitting down and standing up for 30 s. The chi-square test or Fischer Exact was used for possible associations among the variables; the t-test for independent samples was used to compare the averages among the groups; the value of significance adopted was 5%.

RESULTS

There was an association between the polymorphism of the HTR2A gene with FM, demonstrating that carriers of the genotype GG have 24.39 times more likely to develop the syndrome (IC95% 5.15-115.47; p = 0.01). It was observed an association between FM and the test to sit and stand up demonstrating that women with fibromyalgia have lower limb muscle strength (p = 0.01). The study showed that the white race has 3.84 times more likely to develop FM (p = 0.01).

CONCLUSION

The results of this study suggest that women of Caucasian ethnicity with GG genotype or G allele presented greater risk of developing fibromyalgia and that these patients have lower limb muscle strength compared to the control group.

Long-term outcomes of adolescents with juvenile-onset fibromyalgia into adulthood and impact of depressive symptoms on functioning over time

Juvenile-onset fibromyalgia (JFM) is typically diagnosed in adolescence and characterized by widespread pain and marked functional impairment. The long-term impact of JFM into adulthood is poorly understood. The objectives of this study were to describe physical and psychosocial outcomes of youth diagnosed with JFM in early adulthood (∼8-year follow-up), examine longitudinal trajectories of pain and depressive symptoms from adolescence to young adulthood, and examine the impact of pain and depressive symptoms on physical functioning over time. Participants were 97 youth with JFM enrolled in a prospective longitudinal study in which pain symptoms, and physical and psychosocial functioning were assessed at 4 time points over approximately 8 years. At the time 4 follow-up (Mage = 24.2 years), the majority continued to suffer from pain and impairment in physical, social, and psychological domains. However, trajectories of pain and emotional symptoms showed varying patterns. Longitudinal analysis using growth mixture modeling revealed 2 pain trajectories (Steady Improvement and Rapid Rebounding Improvement), whereas depressive symptoms followed 3 distinct trajectories (Low-Stable, Improving, and Worsening). Membership in the Worsening Depressive symptoms group was associated with poorer physical functioning over time (P < 0.001) compared with the Low-Stable and Improving groups. This study offers evidence that although JFM symptoms persist for most individuals, pain severity tends to decrease over time. However, depressive symptoms follow distinct trajectories that indicate subgroups of JFM. In particular, JFM patients with worsening depressive symptoms showed decreasing physical functioning and may require more intensive and consistent intervention to prevent long-term disability.

Hyperbaric Oxygen Therapy Can Induce Neuroplasticity and Significant Clinical Improvement in Patients Suffering From Fibromyalgia With a History of Childhood Sexual Abuse-Randomized Controlled Trial

Background: Fibromyalgia syndrome (FMS), a condition considered to represent a prototype of central sensitization syndrome, can be induced by different triggers including childhood sexual abuse (CSA). Recent studies have demonstrated hyperbaric oxygen therapy (HBOT) can induce neuroplasticity and improve clinical outcome of FMS. The aim of the current study was to evaluate the effect of HBOT on patients suffering from FMS with a history of CSA.

Materials and methods: A prospective randomized clinical trial conducted between July 2015 and November 2017 included women with a history of CSA who fulfilled fibromyalgia diagnosis criteria for at least 5 years prior to inclusion. Included participants (N = 30) were randomly assigned to treatment group, treated with 60 HBOT sessions and a control/crossover group received psychotherapy. After the control period, the control/crossover group was crossed to HBOT. Clinical outcomes were assessed using FMS questioners, post-traumatic stress disorder (PTSD) questioners and quality of life questioners. Objective outcome were assessed using brain function and structure imaging.

Findings: Following HBOT, there was a significant improvement in all FMS questionnaires (widespread pain index, Fibromyalgia symptoms severity scale, Fibromyalgia functional impairment), most domains of quality of life, PTSD symptoms and psychological distress. The same significant improvements were demonstrated in the control following crossover to HBOT. Following HBOT, brain SPECT imaging demonstrated significant increase in brain activity in the prefrontal cortex, orbital frontal cortex, and subgenual area (p < 0.05). Brain microstructure improvement was seen by MRI-DTI in the anterior thalamic radiation (p = 0.0001), left Insula (p = 0.001), and the right Thalamus (p = 0.001).

Conclusion: HBOT induced significant clinical improvement that correlates with improved brain functionality and brain microstructure in CSA related FMS patients.

Trial Registration:www.Clinicaltrials.gov, identifier: NCT03376269. url: https://clinicaltrials.gov/show/NCT03376269

Recovery of Repressed Memories in Fibromyalgia Patients Treated With Hyperbaric Oxygen - Case Series Presentation and Suggested Bio-Psycho-Social Mechanism

Fibromyalgia Syndrome (FMS) is a condition considered to represent a prototype of central sensitization syndrome, characterized by chronic widespread pain and along with symptoms of fatigue, non-restorative sleep and cognitive difficulties. FMS can be induced by trauma, infection or emotional stress with cumulative evidence that dissociation is relatively frequent in FMS patients. Two randomized controlled trials have shown that hyperbaric oxygen therapy (HBOT) can induce neuroplasticity and be effective in patients suffering from FMS. In this paper we present, for the first time, case series of female fibromyalgia patients who, in the course of HBOT, suddenly recalled repressed traumatic memories of childhood sexual abuse (CSA). The surfacing of the repressed (dissociative) memories decades after the sexual abuse events was sudden and utterly surprising. No psychological intervention was involved. As the memories surfaced, the physical pain related to FMS subsided. In one patient who had brain single photon emission CT (SPECT) before and after HBOT, the prefrontal cortex appeared suppressed before and reactivated after. The 3 cases reported in this article are representative of a total of nine fibromyalgia patients who experienced a retrieval of repressed memory during HBOT. These cases provide insights on dissociative amnesia and suggested mechanism hypothesis that is further discussed in the article. Obviously, prospective studies cannot be planned since patients are not aware of their repressed memories. However, it is very important to keep in mind the possibility of surfacing memories when treating fibromyalgia patients with HBOT or other interventions capable of awakening dormant brain regions.

WITHDRAWN: Anticonvulsants for fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a clinically well-defined chronic condition of unknown aetiology characterised by chronic widespread pain that often co-exists with sleep problems and fatigue. People often report high disability levels and poor health-related quality of life (HRQoL). Drug therapy focuses on reducing key symptoms and disability, and improving HRQoL. Anticonvulsants (antiepileptic drugs) are drugs frequently used for the treatment of chronic pain syndromes.

OBJECTIVES

To assess the benefits and harms of anticonvulsants for treating FM symptoms.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 8, 2013), MEDLINE (1966 to August 2013), PsycINFO (1966 to August 2013), SCOPUS (1980 to August 2013) and the reference lists of reviewed articles for published studies and www.clinicaltrials.gov (to August 2013) for unpublished trials.

SELECTION CRITERIA

We selected randomised controlled trials of any formulation of anticonvulsants used for the treatment of people with FM of any age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data of all included studies and assessed the risks of bias of the studies. We resolved discrepancies by discussion.

MAIN RESULTS

We included eight studies: five with pregabalin and one study each with gabapentin, lacosamide and levetiracetam. A total of 2480 people were included into anticonvulsants groups and 1099 people in placebo groups. The median therapy phase of the studies was 13 weeks. The amount and quality of evidence were insufficient to draw definite conclusions on the efficacy and safety of gabapentin, lacosamide and levetiracetam in FM. The amount and quality of evidence was sufficient to draw definite conclusions on the efficacy and safety of pregabalin in FM. Therefore, we focused on our interpretation of the evidence for pregabalin due to our greater certainty about its effects and its greater relevance to clinical practice. All pregabalin studies had a low risk of bias. Reporting a 50% or greater reduction in pain was more frequent with pregabalin use than with a placebo (risk ratio (RR) 1.59; 95% confidence interval (CI) 1.33 to 1.90; number needed to treat for an additional beneficial outcome (NNTB) 12; 95% CI 9 to 21). The number of people who reported being 'much' or 'very much' improved was higher with pregabalin than with placebo (RR 1.38; 95% CI 1.23 to 1.55; NNTB 9; 95% CI 7 to 15). Pregabalin did not substantially reduce fatigue (SMD -0.17; 95% CI -0.25 to -0.09; 2.7% absolute improvement on a 1 to 50 scale) compared with placebo. Pregabalin had a small benefit over placebo in reducing sleep problems by 6.2% fewer points on a scale of 0 to 100 (standardised mean difference (SMD) -0.35; 95% CI -0.43 to -0.27). The dropout rate due to adverse events was higher with pregabalin use than with placebo use (RR 1.68; 95% CI 1.36 to 2.07; number needed to treat for an additional harmful outcome (NNTH) 13; 95% CI 9 to 23). There was no significant difference in serious adverse events between pregabalin and placebo use (RR 1.03; 95% CI 0.71 to 1.49). Dizziness was reported as an adverse event more frequently with pregabalin use than with placebo use (RR 3.77; 95% CI 3.06 to 4.63; NNTH 4; 95% CI 3 to 5).

AUTHORS' CONCLUSIONS

The anticonvulsant, pregabalin, demonstrated a small benefit over placebo in reducing pain and sleep problems. Pregabalin use was shown not to substantially reduce fatigue compared with placebo. Study dropout rates due to adverse events were higher with pregabalin use compared with placebo. Dizziness was a particularly frequent adverse event seen with pregabalin use. At the time of writing this review, pregabalin is the only anticonvulsant drug approved for treating FM in the US and in 25 other non-European countries. However, pregabalin has not been approved for treating FM in Europe. The amount and quality of evidence were insufficient to draw definite conclusions on the efficacy and safety of gabapentin, lacosamide and levetiracetam in FM.

Fibromyalgia syndrome pathology and environmental influences on afflictions with medically unexplained symptoms

Fibromyalgia syndrome (FMS) is a clinical disorder predominant in females with unknown etiology and medically unexplained symptoms (MUS), similar to other afflictions, including irritable bowel syndrome (IBS), chronic fatigue syndrome (CFS), post-traumatic stress disorder (PTSD), Gulf War illness (GFI), and others. External environmental stimuli drive behavior and impact physiologic homeostasis (internal environment) via autonomic functioning. These environments directly impact the individual affective state (mind), which feeds back to regulate physiology (body). FMS has emerged as a complex disorder with pathologies identified among neurotransmitter and enzyme levels, immune/cytokine functionality, cortical volumes, cutaneous innervation, as well as an increased frequency among people with a history of traumatic and/or emotionally negative events, and specific personality trait profiles. Yet, quantitative physical evidence of pathology or disease etiology among FMS has been limited (as with other afflictions with MUS). Previously, our group published findings of increased peptidergic sensory innervation associated with the arterio-venous shunts (AVS) in the glabrous hand skin of FMS patients, which provides a plausible mechanism for the wide-spread FMS symptomology. This review focuses on FMS as a model affliction with MUS to discuss the implications of the recently discovered peripheral innervation alterations, explore the role of peripheral innervation to central sensitization syndromes (CSS), and examine possible estrogen-related mechanisms through which external and internal environmental factors may contribute to FMS etiology and possibly other afflictions with MUS.

Fibrofascitis - An Enigma for the Dentist: A Case Report

Fibromyalgia is a chronic syndrome that causes widespread musculoskeletal pain and stiffness throughout the connective tissues that support and move the bones and joints. Pain and localized tender points occur in the muscles, particularly those that support the neck, spine, shoulders, and hips. Moreover the disorder includes fatigue, depression, sleep disturbances and constipation. A combination of treatments including medications, patient education, physical therapy and counseling are usually recommended. Here, we present a case report of fibromyalgia and the treatment given to the patient, a combination of dental and orthopedic treatment.

Heart Rate Variability for Quantification of Autonomic Dysfunction in Fibromyalgia

Objective

To quantify autonomic dysfunction in fibromyalgia patients compared to healthy controls using heart rate variability (HRV).

Methods

Sixteen patients with fibromyalgia and 16 healthy controls were recruited in this case control study. HRV was measured using the time-domain method incorporating the following parameters: total heartbeats, the mean of intervals between consecutive heartbeats (R-R intervals), the standard deviation of normal to normal R-R intervals (SDNN), the square root of the mean squared differences of successive R-R intervals (RMSSD), ratio of SDNN to RMSSD (SDNN/RMSSD), and difference between the longest and shortest R-R interval under different three conditions including normal quiet breathing, rate controlled breathing, and Valsalva maneuver. The severity of autonomic symptoms in the group of patients with fibromyalgia was measured by Composite Autonomic Symptom Scale 31 (COMPASS 31). Then we analyzed the difference between the fibromyalgia and control groups and the correlation between the COMPASS 31 and aforementioned HRV parameters in the study groups.

Results

Patients with fibromyalgia had significantly higher SDNN/RMSSD values under both normal quiet breathing and rate controlled breathing compared to controls. Differences between the longest and shortest R-R interval under Valsalva maneuver were also significantly lower in patients with fibromyalgia than in controls. COMPASS 31 score was negatively correlated with SDNN/RMSSD values under rate controlled breathing.

Conclusion

SDNN/RMSSD is a valuable parameter for autonomic nervous system function and can be used to quantify subjective autonomic symptoms in patients with fibromyalgia.

Physical Trauma and Infection as Precipitating Factors in Patients with Fibromyalgia

OBJECTIVE

The objective of this study was to evaluate both precipitating factors in patients with fibromyalgia and any differences in clinical presentation, symptom severity, and quality-of-life between those with and without precipitating physical trauma or infection.

DESIGN

In a retrospective cross-sectional study, the authors compared patient characteristics and fibromyalgia symptom severity and quality-of-life with the Fibromyalgia Impact Questionnaire and the Short Form-36 Health Survey in patients seen in a fibromyalgia treatment program.

RESULTS

Of 939 patients, 27% reported precipitating factors (trauma, n = 203; infection, n = 53), with the rest having idiopathic fibromyalgia (n = 683). Patients with precipitating trauma were more likely to have worse Fibromyalgia Impact Questionnaire physical function than patients with idiopathic onset (P = 0.03). Compared with patients with idiopathic onset and precipitating trauma, patients with precipitating infection were more likely to have worse Short Form-36 Health Survey physical component summary (P = 0.01 and P = 0.003) but better role emotional (P = 0.04 and P = 0.005), mental health index (P = 0.02 and P = 0.007), and mental component summary (P = 0.03 and P = 0.004), respectively.

CONCLUSIONS

One-fourth of this study's patients with fibromyalgia had precipitating physical trauma or infection. Patients with precipitating infection had different sociodemographic characteristics, clinical presentation, and quality-of-life from the idiopathic and trauma groups. Further studies are needed to look into the relationships between precipitating events and fibromyalgia.

Depressive-like symptoms in a reserpine-induced model of fibromyalgia in rats

Since the pathogenesis of fibromyalgia is unknown, treatment options are limited, ineffective and in fact based on symptom relief. A recently proposed rat model of fibromyalgia is based on central depletion of monamines caused by reserpine administration. This model showed widespread musculoskeletal pain and depressive-like symptoms, but the methodology used to measure such symptoms has been criticized. Evidence relates the high prevalence of pain and depression in fibromyalgia to common pathogenic pathways, most probably focused on the monoaminergic system. The present study aims at a validation of the reserpine model of fibromyalgia. For this purpose, rats undergoing this model have been tested for depressive-like symptoms with a Novelty-Suppressed Feeding Test adaptation. Animals administered with reserpine and subjected to forced food deprivation performed a smaller number of incursions to the center of the open field, evidenced by a decrease in the per-minute rate of the rats' approaching, smelling or touching the food. They also took more time to eat from the central food than control rats. These NSFT findings suggest the presence of depressive-like disorders in this animal model of fibromyalgia.

Effect of transcutaneous electrical nerve stimulation on pain, function, and quality of life in fibromyalgia: a double-blind randomized clinical trial

BACKGROUND

Fibromyalgia is a common chronic pain condition that has a significant impact on quality of life and often leads to disability. To date, there have been few well-controlled trials assessing the utility of nonpharmacological treatment modalities such as transcutaneous electrical nerve stimulation (TENS) in the management of pain and improvement in function in individuals with fibromyalgia.

OBJECTIVES

The purpose of this study will be to complete a long-term, multicenter study to assess the effects of TENS in women with fibromyalgia.

DESIGN

This will be a phase II randomized, double-blind, placebo-controlled, multicenter clinical trial.

PARTICIPANTS

Three hundred forty-three participants with fibromyalgia will be recruited for this study.

INTERVENTION

Participants will be randomly assigned to 1 of 3 groups: the intervention (TENS), placebo, or no treatment. After completing the randomized period, all participants will receive the intervention for 1 month. The participants will be asked to use TENS at the highest tolerable level for at least 2 hours daily during physical activity.

MEASUREMENTS

The primary outcome will be pain with movement, with secondary outcomes assessing functional abilities, patient-reported outcomes, and quantitative sensory testing.

LIMITATIONS

Because having participants refrain from their typical medications is not practical, their usage and any change in medication use will be recorded.

CONCLUSIONS

The results of this study will provide some of the first evidence from a large-scale, double-blind, placebo-controlled trial on the effectiveness of TENS on pain control and quality-of-life changes in patients with fibromyalgia.

Healthcare Costs Associated With Chronic Opioid Use and Fibromayalgia Syndrome

BACKGROUND

Fibromyalgia (FM) is an idiopathic, functional syndrome characterized by chronic, widespread pain and diffuse tenderness. This disorder affects more than 6 million patients in the United States and is associated with significant clinical and economic burdens.

OBJECTIVES

The objectives of this study were to: 1) estimate the costs associated with a FM diagnosis; and 2) estimate the impact of chronic opioid use on the costs of FM patients.

RESEARCH DESIGN

Case-control study.

METHODS

Subjects were identified in a large nationally representative database of commercially insured patients. Propensity score-matched analyses included 445,912 FM-control pairs in the first analysis, while the second analysis included 48,333 chronic opioid users with the FM-control pairs. Primary outcomes of interest were the medical and prescription costs compared between matched pairs, based on propensity for being a case as evidenced by coefficients obtained from a first-stage logistic regression. Patient characteristics considered include: state of residence, diagnosing provider type, comorbid conditions, and concurrent medication use.

RESULTS

When controlling for propensity to receive a FM diagnosis, the actual diagnosis has a small effect on medical (-$83.54 [95% CI, -152.55 to -16.53]) and prescription ($120.31 [95% CI, 109.98-130.62]) costs. However, the effect of chronic opioid use in FM patients on medical ($9094.05 [95% CI, 8924.79-9263.31]) and prescription ($3391.81 [95% CI, 3368.84-3414.79]) costs is much more substantial.

CONCLUSIONS

While the differences seen in FM patients and controls are marginal, those attributed to chronic opioid use in these patients are significantly higher. Chronic opioid therapy to treat FM is a practice based not on evidence available to practitioners, but on other variables.

Association between fibromyalgia and adverse perioperative outcomes

BACKGROUND

Fibromyalgia, the classic non-inflammatory pain syndrome, has been associated with chronic inflammatory makers which are linked with increased morbidity and mortality. We tested the primary hypothesis that patients with fibromyalgia undergoing hospital procedures have a high risk of cardiovascular complications. Our secondary goals were to evaluate the association of fibromyalgia with: (i) in-hospital thromboembolic events, (ii) in-hospital mortality, and (iii) in-hospital microvascular complications.

METHODS

We obtained 21.78 million discharge records from 2009 to 2010 from the US Agency for Healthcare Research and Quality censuses across the seven states. We matched fibromyalgia records and compared records with controls based on age, gender, state of discharge, principal procedure, and a propensity score developed from the set of diagnosis-related predictors. A multivariable logistic regression was used to compare matched fibromyalgia patients and controls on the primary and secondary outcomes.

RESULTS

We matched 89 589 pairs for a total sample size of 179 178 discharge records. The adjusted odds ratio for in-hospital cardiovascular complications was 1.04 [99% confidence interval (CI): 0.90-1.19, P=0.51], for thromboembolic events was 1.03 (99% CI: 0.93-1.15, P=0.46), for in-hospital mortality was 0.81 (99% CI: 0.73-0.89, P<0.001), and for microvascular complications was 0.96 (99% CI: 0.88, 1.04, P=0.18). Two separate sensitivity analyses produced results similar to that of the primary analysis for all three complication outcomes.

CONCLUSIONS

We found no evidence that the diagnosis of fibromyalgia increased the risk of in-hospital complications. Fibromyalgia seems to be associated with a reduction in in-hospital mortality, but this requires confirmation with a large prospective controlled study.

Personality profiles and coping styles in migraine patients with fibromyalgia comorbidity

Fibromyalgia syndrome (FM) is frequently associated with migraine. In this study we aimed to compare personality profiles and coping styles across 23 migraine without aura patients sharing FM comorbidity (MWA-FM), 28 migraine without aura patients without FM symptoms (MWA) and 51 age- and sex-matched controls, by means of Big Five Questionnaire (BFQ) and Coping Orientation to Problem Experienced (COPE), and to correlate main results with clinical features. The "Energy" personality factor was significantly reduced in patients presenting with FM symptoms, compared to both migraine without aura patients and controls. A low score in "Dynamism" sub-item with a high score in denial coping style was able to distinguish MWA from MW-FM groups with an accuracy of 82.35% (Wilks lambda=0.98; chi-square=8.99, DF=1, p=0.005). In particular, lower "Dynamism" scores corresponded to a major expression of allodynia, fatigue, anxiety, depression, headache frequency and poor quality of sleep and life. Avoidance from active coping with stressful events may facilitate worsening of migraine and fibromyalgia comorbidity.

Anticonvulsants for fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a clinically well-defined chronic condition of unknown aetiology characterised by chronic widespread pain that often co-exists with sleep problems and fatigue. People often report high disability levels and poor health-related quality of life (HRQoL). Drug therapy focuses on reducing key symptoms and disability, and improving HRQoL. Anticonvulsants (antiepileptic drugs) are drugs frequently used for the treatment of chronic pain syndromes.

OBJECTIVES

To assess the benefits and harms of anticonvulsants for treating FM symptoms.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 8, 2013), MEDLINE (1966 to August 2013), PsycINFO (1966 to August 2013), SCOPUS (1980 to August 2013) and the reference lists of reviewed articles for published studies and www.clinicaltrials.gov (to August 2013) for unpublished trials.

SELECTION CRITERIA

We selected randomised controlled trials of any formulation of anticonvulsants used for the treatment of people with FM of any age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data of all included studies and assessed the risks of bias of the studies. We resolved discrepancies by discussion.

MAIN RESULTS

We included eight studies: five with pregabalin and one study each with gabapentin, lacosamide and levetiracetam. A total of 2480 people were included into anticonvulsants groups and 1099 people in placebo groups. The median therapy phase of the studies was 13 weeks. The amount and quality of evidence were insufficient to draw definite conclusions on the efficacy and safety of gabapentin, lacosamide and levetiracetam in FM. The amount and quality of evidence was sufficient to draw definite conclusions on the efficacy and safety of pregabalin in FM. Therefore, we focused on our interpretation of the evidence for pregabalin due to our greater certainty about its effects and its greater relevance to clinical practice. All pregabalin studies had a low risk of bias. Reporting a 50% or greater reduction in pain was more frequent with pregabalin use than with a placebo (risk ratio (RR) 1.59; 95% confidence interval (CI) 1.33 to 1.90; number needed to treat for an additional beneficial outcome (NNTB) 12; 95% CI 9 to 21). The number of people who reported being 'much' or 'very much' improved was higher with pregabalin than with placebo (RR 1.38; 95% CI 1.23 to 1.55; NNTB 9; 95% CI 7 to 15). Pregabalin did not substantially reduce fatigue (SMD -0.17; 95% CI -0.25 to -0.09; 2.7% absolute improvement on a 1 to 50 scale) compared with placebo. Pregabalin had a small benefit over placebo in reducing sleep problems by 6.2% fewer points on a scale of 0 to 100 (standardised mean difference (SMD) -0.35; 95% CI -0.43 to -0.27). The dropout rate due to adverse events was higher with pregabalin use than with placebo use (RR 1.68; 95% CI 1.36 to 2.07; number needed to treat for an additional harmful outcome (NNTH) 13; 95% CI 9 to 23). There was no significant difference in serious adverse events between pregabalin and placebo use (RR 1.03; 95% CI 0.71 to 1.49). Dizziness was reported as an adverse event more frequently with pregabalin use than with placebo use (RR 3.77; 95% CI 3.06 to 4.63; NNTH 4; 95% CI 3 to 5).

AUTHORS' CONCLUSIONS

The anticonvulsant, pregabalin, demonstrated a small benefit over placebo in reducing pain and sleep problems. Pregabalin use was shown not to substantially reduce fatigue compared with placebo. Study dropout rates due to adverse events were higher with pregabalin use compared with placebo. Dizziness was a particularly frequent adverse event seen with pregabalin use. At the time of writing this review, pregabalin is the only anticonvulsant drug approved for treating FM in the US and in 25 other non-European countries. However, pregabalin has not been approved for treating FM in Europe. The amount and quality of evidence were insufficient to draw definite conclusions on the efficacy and safety of gabapentin, lacosamide and levetiracetam in FM.

Chronic opioid use in fibromyalgia syndrome: a clinical review

Chronic opioid therapy in the treatment of chronic nonmalignant pain has increased drastically over the past decade. This is a worrisome trend in general, but specifically, given pathophysiologic characteristics seen in fibromyalgia (FM) syndrome patients, the use of this class of medication deserves special scrutiny. We first describe the current understanding of the etiology and pathophysiology of FM, including the role of genetic and environmental factors in the development of this syndrome. We then discuss the biologic effects of opioid use. Next, we review the pharmaceutical treatment options for FM, including 3 Food and Drug Administration-approved medications, and the evolution of treatment guidelines since 2004. We then highlight the various consequences associated with the mechanism of action of opioids and the specific concerns for FM patients.Finally, summarizing the existing literature, we make the case that chronic opioid use is inappropriate in the treatment of FM because of the interaction of unique pathophysiologic characteristics of the patients and effects associated with chronic opioid use.

Efficacy and safety of medicinal plants or related natural products for fibromyalgia: a systematic review

To assess the effects of medicinal plants (MPs) or related natural products (RNPs) on fibromyalgia (FM) patients, we evaluate the possible benefits and advantages of MP or RNP for the treatment of FM based on eight randomized placebo-controlled trials (RCTs) involving 475 patients. The methodological quality of all studies included was determined according to JADAD and “Risk of Bias” with the criteria in the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0. Evidence suggests significant benefits of MP or RNP in sleep disruption, pain, depression, joint stiffness, anxiety, physical function, and quality of life. Our results demonstrated that MP or RNP had significant effects on improving the symptoms of FM compared to conventional drug or placebo; longer tests are required to determine the duration of the treatment and characterize the long-term safety of using MP, thus suggesting effective alternative therapies in the treatment of pain with minimized side effects.

Geographic variation of chronic opioid use in fibromyalgia

BACKGROUND

Opioid use for the treatment of chronic nonmalignant pain has increased drastically over the past decade. Although no evidence of efficacy exists supporting the treatment of fibromyalgia (FM) with chronic opioid therapy, a large number of patients are receiving this therapy. Geographic variation in the use of opioids has been demonstrated in the past, but there are no studies examining variation of chronic opioid use.

OBJECTIVE

This study examines both the extent of geographic variation and the factors associated with variation across states of chronic opioid use among patients with FM.

METHODS

Using a large, nationally representative dataset of commercially insured individuals, the following characteristics were examined: sex, disease prevalence, physician prevalence, illicit drug use, and the prescence of a prescription monitoring program. Other contextual and structural characteristics were also assessed.

RESULTS

The analysis included 245,758 patients with FM; 11.3% received chronic opioid therapy during the study period. There was a 5-fold difference between the states with the lowest rate of use (~4%) and those with the highest (~20%). The weighted %CV was 36.2%. Percent female and previous illicit opioid use rates were associated with higher rates of chronic opioid use, and FM prevalence and physician prevalence were associated with lower rates. The presence of a prescription monitoring program was not significantly correlated.

CONCLUSIONS

Geographic variation in chronic opioid use among patients with FM exists at rates similar to those seen in other studies examining opioid use. This large level of geographic variation suggests that the prescribing decision is not based solely on physician-patient interaction but also on contextual and structural factors at the state level. The level of physician and condition prevalence suggest that information dissemination and peer-to-peer interaction may play a key role in adopting evidence-based medicine for the treatment of patients suffering from FM and related conditions. Level of diagnosis prevalence as a predictor of evidence-based practice has not been reported in the literature and is an important contribution to research on geographic variation.

Screening for the presence of FMR1 premutation alleles in women with fibromyalgia

Fibromyalgia is a chronic condition characterized by widespread pain, fatigue, non-restorative sleep and cognitive difficulties that affects 2-4% of the general population. Recently a possible relationship between the FMR1 premutation and fibromyalgia has been pointed out. In attempt to gather more data we screened for the FMR1 CGG expansion 700 DNA samples from unrelated fibromyalgia patients. This data might be useful for evaluating the incorporation of this test in rheumatologic procedures for women with fibromyalgia. The observed frequency of FMR1 premutation carriers (3 of 700, 0.4%) is not significantly different from the estimated rate in the general female population (1/250-1/400) (P=0.539, P=0.716). Clinical examination of the FMR1 premutation carriers identified revealed that all of them had important neurological symptoms with regard to muscular symptoms, neurocognitive alterations and neurovegetative impairments. With regard to other clinical aspects of the disease the cases apparently did not differ from the average fibromyalgia patients. On the basis of our results an FMR1 screening among fibromyalgia female patients would not be recommended. However it would be worthwhile to further evaluate the different clinical presentations that fibromyalgia patients might present based on their FMR1 premutation carrier status.

Are there gender differences in quality of life and symptomatology between fibromyalgia patients?

The purpose of this study is to examine gender differences in quality of life (QoL) and symptomatology in fibromyalgia (FM) patients. A total of 20 men (48.0 ± 8.0 years) and 78 women (49.8 ± 7.2 years) with FM participated in the study (age range 31-63 years). Health-related QoL and FM impact were assessed by means of the Spanish versions of the Short-Form-36 Health Survey (SF36) and the Fibromyalgia Impact Questionnaire (FIQ), respectively. Comparisons in QoL were performed using one-way analysis of covariance adjusted by age and body mass index (BMI), and comparisons in FIQ dimensions were performed using Mann-Whitney test. Overall FM impact, as measured by FIQ-total score (p = .01) and FIQ-physical impairment (p = .02) was higher in men, whereas women presented higher values of FIQ-fatigue and FIQ-morning tiredness (p = .04) and less SF36-vitality (p = .02). Therefore, women appear to feel more fatigue, whereas men present higher FM overall impact. Due to the small number of men included in this study and the consequent small statistical power, these results should be taken as preliminary. Higher powered studies are warranted to further address gender differences in FM in order to design more successful treatments.

Trauma and work-related pain syndromes: risk factors, clinical picture, insurance and law interventions

In the past decade, major progress has been made in our understanding of fibromyalgia syndrome (FMS). Various triggers have been implicated as contributing to symptom development in FMS when genetically susceptible individuals are challenged. A substantial amount of data points towards the association between trauma and chronic widespread pain/fibromyalgia syndrome (CWP/FMS). There is abundant data suggesting that the pathogenesis of CWP/FMS might be related to cervical spine injury. Furthermore, several persistent local pain conditions may progress to CWP/FMS. These conditions may share a common pathogenic mechanism namely, central sensitisation. Physical trauma and emotional trauma co-exist in many traumatic events and may interact in the pathogenesis of CWP/FMS.

Fibromyalgia syndrome and spa therapy: myth or reality?

Fibromyalgia syndrome (FS) is a common musculoskeletal disorder characterized by otherwise unexplained chronic widespread pain, a lowered pain threshold, high tender point counts, sleep disturbances, fatigue, headache, irritable bowel syndrome, morning stiffness, paraesthesias in the extremities, often psychological distress and depressed mood. Consequently, FS has a negative impact on working capacity, family life, social functioning and quality of life. Because of unknown etiology and not clearly understood pathogenesis, there is no standard therapy regime for FS. A variety of medical treatments, including antidepressants, opioids, analgesic or non-steroidal anti-inflammatory drugs, sedatives, muscle relaxants and antiepileptics, have been used to treat FS. Currently, no pharmacological treatment for FS is consistently successful. According to recent guidelines, the optimal treatment of FS requires a multidisciplinary approach with a combination of non-pharmacological and pharmacological treatment modalities. Spa therapy is a popular treatment for FS in many European countries, as well as in Japan and Israel. However, despite their long history and popularity spa treatments are still the subject of debate and their role in modern medicine is still not clear. The objective of this review is to summarize the currently available information on clinical effects and mechanism of action of spa therapy in FS. We also provide some suggestions for further development in this area.

Central amplification and fibromyalgia: disorder of pain processing

Fibromyalgia (FM), a complex chronic pain disorder affecting a heterogeneous patient population, is an area of active basic and clinical research. Although diagnostic criteria for FM have been available for 2 decades, there remains no definitive diagnostic and no consensus regarding its etiology. Accumulating evidence suggests the underlying cause of FM pain results from abnormal pain processing particularly in the central nervous system rather than from dysfunction in peripheral tissues where pain is perceived. In this review, we examine recent studies investigating abnormalities in central pain processing as a component of FM in both preclinical models of generalized muscle hypersensitivity and clinical research in patients with FM. We focus our discussion on two areas where strong evidence exists for abnormalities in sensory signaling: the reduction of descending control, including suppression of descending inhibitory pathways and/or enhancement of descending facilitatory pathways, and changes in key neurotransmitters associated with central sensitization. Finally, we discuss currently available pharmacological treatments indicated for the management of pain in FM patients, based on their proposed mechanism of action and efficacy.

Fibromyalgia: When Distress Becomes (Un)sympathetic Pain

Fibromyalgia is a painful stress-related disorder. A key issue in fibromyalgia research is to investigate how distress could be converted into pain. The sympathetic nervous system is the main element of the stress response system. In animal models, physical trauma, infection, or distressing noise can induce abnormal connections between the sympathetic nervous system and the nociceptive system. Dorsal root ganglia sodium channels facilitate this type of sympathetic pain. Similar mechanisms may operate in fibromyalgia. Signs of sympathetic hyperactivity have been described in this condition. Genetic factors and/or distressful lifestyle may lead to this state of sympathetic hyperactivity. Trauma and infection are recognized fibromyalgia triggers. Women who suffer from fibromyalgia have catecholamine-evoked pain. Sympathetic dysfunction may also explain nonpain-related fibromyalgia symptoms. In conclusion, in fibromyalgia, distress could be converted into pain through forced hyperactivity of the sympathetic component of the stress response system.

Fibromyalgia in fragile X mental retardation 1 gene premutation carriers

OBJECTIVE

FM is a disorder of altered pain regulation and is characterized by pain, fatigue, poor sleep and psychological impairments; thus, it is classified as a central sensitivity syndrome. Female carriers of a premutation in the fragile X mental retardation 1 (FMR1) gene frequently have widespread musculoskeletal pain and sometimes have been diagnosed with FM, especially if they have the motor signs of fragile X-associated tremor ataxia syndrome (FXTAS). Studies suggest that FM occurs in persons with a genetic predisposition. We describe the clinical features of female FMR1 premutation carriers with symptoms of FM.

METHODS

A sample of patients was selected that participated in studies at two tertiary referral academic centres on the phenotype and therapy of FXTAS.

RESULTS

This selected sample of patients, five female premutation carriers, has FM symptoms or diagnoses and other central sensitivity syndromes.

CONCLUSION

Since FM affects 2-4% of the world's population and about 1 in 250 females are FMR1 carriers, a study screening females with FM for the presence of the FMR1 premutation is worthwhile. A finding of increased prevalence of FMR1 carriers among females with FM would impact the standard evaluation of FM. Presently, guidelines for FMR1 genetic testing includes early menopause, congenital intellectual disability, autism spectrum disorder, tremor or ataxia, and a family history of FXTAS or fragile X syndrome. The latter is a common cause of autism and developmental delay. Such testing is important because female carriers are at risk of having a child with fragile X syndrome.

The role of the central nervous system in the generation and maintenance of chronic pain in rheumatoid arthritis, osteoarthritis and fibromyalgia

Pain is a key component of most rheumatologic diseases. In fibromyalgia, the importance of central nervous system pain mechanisms (for example, loss of descending analgesic activity and central sensitization) is well documented. A few studies have also noted alterations in central pain processing in osteoarthritis, and some data, including the observation of widespread pain sensitivity, suggest that central pain-processing defects may alter the pain response in rheumatoid arthritis patients. When central pain is identified, different classes of analgesics (for example, serotonin-norepinephrine reuptake inhibitors, α2δ ligands) may be more effective than drugs that treat peripheral or nociceptive pain (for example, nonsteroidal anti-inflammatory drugs and opioids).

Cannabis use in patients with fibromyalgia: effect on symptoms relief and health-related quality of life

Background

The aim of this study was to describe the patterns of cannabis use and the associated benefits reported by patients with fibromyalgia (FM) who were consumers of this drug. In addition, the quality of life of FM patients who consumed cannabis was compared with FM subjects who were not cannabis users.

Methods

Information on medicinal cannabis use was recorded on a specific questionnaire as well as perceived benefits of cannabis on a range of symptoms using standard 100-mm visual analogue scales (VAS). Cannabis users and non-users completed the Fibromyalgia Impact Questionnaire (FIQ), the Pittsburgh Sleep Quality Index (PSQI) and the Short Form 36 Health Survey (SF-36).

Results

Twenty-eight FM patients who were cannabis users and 28 non-users were included in the study. Demographics and clinical variables were similar in both groups. Cannabis users referred different duration of drug consumption; the route of administration was smoking (54%), oral (46%) and combined (43%). The amount and frequency of cannabis use were also different among patients. After 2 hours of cannabis use, VAS scores showed a statistically significant (p<0.001) reduction of pain and stiffness, enhancement of relaxation, and an increase in somnolence and feeling of well being. The mental health component summary score of the SF-36 was significantly higher (p<0.05) in cannabis users than in non-users. No significant differences were found in the other SF-36 domains, in the FIQ and the PSQI.

Conclusions

The use of cannabis was associated with beneficial effects on some FM symptoms. Further studies on the usefulness of cannabinoids in FM patients as well as cannabinoid system involvement in the pathophysiology of this condition are warranted.

Pregnancy outcome in patients with fibromyalgia syndrome

OBJECTIVE

To investigate pregnancy outcome of patients with fibromyalgia syndrome (FMS).

METHODS

A retrospective cohort study comparing pregnancies of women with and without FMS was conducted. Multivariable logistic regression models was performed to control for confounders

RESULTS

Deliveries of 112 women with FMS were compared with a control group of 487 deliveries of women without FMS. Parturients with FMS had higher rates of intrauterine growth restriction (IUGR; 7.1% vs. 1.0%, p = 0.001), recurrent abortions (9.8% vs. 1.8%, p < 0.001), gestational diabetes mellitus (14.3% vs. 7%, p = 0.012), and polyhydramnios (12.5% vs. 1.6%, p < 0.001). These patients had lower rates of preterm deliveries (PTD; 6.3% vs. 16.7%, p = 0.018). No significant differences were noted between the groups regarding the rates of cesarean deliveries (CD) (15.2% vs. 21.2%, p = 0.149) and perinatal outcomes such as low Apgar scores (<7) at 1 and 5 min (4.5% vs. 6.7%, p = 0.292 and 1.2% vs. 0.6%, p = 0.372; respectively). Using two multiple logistic regression models, the positive association between FMS and IUGR (adjusted OR = 4.1, 95% CI 1.2-13.2; p = 0.02) and the negative association with PTD (OR = 0.3, 95% CI 0.2-0.6; p = 0.001) remained significant.

CONCLUSION

FMS is an independent risk factor for intrauterine growth restriction. Nevertheless, it is associated with lower rates of preterm deliveries.

The FIBRO System: A Rapid Strategy for Assessment and Management of Fibromyalgia Syndrome

Fibromyalgia syndrome (FMS) is a complex disorder of widespread pain and tenderness associated with numerous other symptoms including fatigue, cognitive dysfunction, nonrestorative sleep, depression, anxiety, and stiffness. While new diagnostic criteria and previous management guidelines require quantitation of the severity of associated FMS symptoms experienced by individual patients, no system for rapid patient assessment has been made available to provide a basis for diagnosis, treatment selection and follow-up for clinicians in busy practices who have limited time. This review presents the FIBRO System, an easily remembered system for FMS symptom quantitation using the FIBRO mnemonic along with verbal questions on simple 0-10 scales to assess symptom severity (the FIBRO Problem Scale) and response to treatment (the FIBRO Change Scale) along with recommendations for pharmacologic and nonpharmacologic therapies to address individual FIBRO symptoms. This symptom-based approach can improve the care of FMS patients by providing a comprehensive, focused assessment in limited time.

[Questionable documentation of the effect of pregabalin in fibromyalgia]

BACKGROUND

Use of Pregabalin has increased considerably in Norway during the last years. One explanation is prescription to patients with diffuse musculo-skeletal pain. The aim of the article is to clarify the effect of pregabalin in fibromyalgia.

MATERIAL AND METHODS

This article is based on literature identified through searches in Medline and public trial registries.

RESULTS

Six randomized, double-blind clinical trials were identified (three of them in peer-reviewed journals) and Pfizer had initiated and sponsored them all. The three trials published in peer-reviewed journals used a numerical rating scale for pain as the primary endpoint, and all trials reported statistically significant improvements on mean pain scores in relation to placebo. The mean pain reduction was between 9 % and 15 %. Effects on secondary endpoints varied considerably, both within and between the studies. Negative results were seldom mentioned in the abstracts, and secondary endpoints were reported incompletely. All 19 reviews referred to one or more of the clinical trials, and were generally limited to describing main results.

INTERPRETATION

Recommendations for pregabalin in treatment of patients with fibromyalgia are based on rather weak evidence. Until trials independent of industry-funding are published, the role of pregabalin in treatment of fibromyalgia remains unclear.