Fibromyalgia: A Critical and Comprehensive Review

Trends in the incidence of chronic fatigue syndrome and fibromyalgia in the UK, 2001-2013: a Clinical Practice Research Datalink study

Objective

Trends in recorded diagnoses of chronic fatigue syndrome (CFS, also known as ‘myalgic encephalomyelitis’ (ME)) and fibromyalgia (FM) in the UK were last reported more than ten years ago, for the period 1990–2001. Our aim was to analyse trends in incident diagnoses of CFS/ME and FM for the period 2001–2013, and to investigate whether incidence might vary by index of multiple deprivation (IMD) score.

Design

Electronic health records cohort study.

Setting

NHS primary care practices in the UK.

Participants

Participants: Patients registered with general practices linked to the Clinical Practice Research Datalink (CPRD) primary care database from January 2001 to December 2013.

Main outcome measure

Incidence of CFS/ME, FM, post-viral fatigue syndrome (PVFS), and asthenia/debility.

Results

The overall annual incidence of recorded cases of CFS/ME was 14.8 (95% CI 14.5, 15.1) per 100,000 people. Overall annual incidence per 100,000 people for FM was 33.3 (32.8–33.8), for PVFS 12.2 (11.9, 12.5), and for asthenia/debility 7.0 (6.8, 7.2). Annual incidence rates for CFS/ME diagnoses decreased from 17.5 (16.1, 18.9) in 2001 to 12.6 (11.5, 13.8) in 2013 (annual percent change −2.8% (−3.6%, −2.0%)). Annual incidence rates for FM diagnoses decreased from 32.3 (30.4, 34.3) to 27.1 (25.5, 28.6) in 2007, then increased to 38.2 (36.3, 40.1) per 100,000 people in 2013. Overall annual incidence of recorded fatigue symptoms was 2246 (2242, 2250) per 100,000 people. Compared with the least deprived IMD quintile, incidence of CFS/ME in the most deprived quintile was 39% lower (incidence rate ratio (IRR) 0.61 (0.50, 0.75)), whereas rates of FM were 40% higher (IRR 1.40 (0.95, 2.06)).

Conclusion

These analyses suggest a gradual decline in recorded diagnoses of CFS/ME since 2001, and an increase in diagnoses of fibromyalgia, with opposing socioeconomic patterns of lower rates of CFS/ME diagnoses in the poorest areas compared with higher rates of FM diagnoses.

Emerging pharmacological strategies for the treatment of fibromyalgia

Fibromyalgia (FM) has been described as a chronic clinical condition related to multisensory hypersensitivity presenting with a complex of symptoms dominated by chronic widespread pain associated with the existence of a range of co-morbidities, such as fatigue, sleep disturbance, cognitive impairment, anxiety and depression. Current treatments include drugs that target serotonin and noradrenaline levels within the central nervous system, e.g., tricyclic antidepressants, serotonin noradrenaline reuptake inhibitors, and voltage-gated calcium channel subunit ligands, e.g., gabapentin and pregabalin. Investigation of a range of novel targets, such as melatoninergic, cannabinoid, dopamine, NMDA, angiotensin, orexin and opioid receptors, and ion channels, in addition revisiting bioamine modulation and subunits has provided efficacy outcomes that improve the health status of patients with FM. Nevertheless, modest and limited efficacy is often observed reflecting the heterogeneity of FM with existence of subpopulations of patients, the contribution of peripheral and central components to the pathophysiology, and the extensive range of accompanying co-morbidities. The complexity and multidimensional nature of FM is emphasized by the diversity of pharmacological targets gaining interest. Clues to underlying mechanisms which offer themselves as novel and potential targets for new medications are being provided by advances in the understanding of the pathophysiology of FM.

Symptoms and the body: Taking the inferential leap

The relationship between the conscious experience of physical symptoms and indicators of objective physiological dysfunction is highly variable and depends on characteristics of the person, the context and their interaction. This relationship often breaks down entirely in the case of "medically unexplained" or functional somatic symptoms, violating the basic assumption in medicine that physical symptoms have physiological causes. In this paper, we describe the prevailing theoretical approach to this problem and review the evidence pertaining to it. We then use the framework of predictive coding to propose a new and more comprehensive model of the body-symptom relationship that integrates existing concepts within a unifying framework that addresses many of the shortcomings of current theory. We describe the conditions under which a close correspondence between the experience of symptoms and objective physiology might be expected, and when they are likely to diverge. We conclude by exploring some theoretical and clinical implications of this new account.

Does volume of physical exercise have an effect on depression in patients with fibromyalgia?

BACKGROUND

Fibromyalgia Syndrome (FMS) is a musculoskeletal disorder frequently associated with depression. We aimed to investigate the association between physical exercise (PE) and depression in patients with FMS, and to evaluate the effect of the weekly volume of PE on depression.

METHODS

A total of 215 FMS patients with depression were evaluated with the Beck Depression Inventory, and were also classified as inactive, insufficiently active, or active. We performed binary logistic regression, with PE as the dependent variable and the level of depression as an independent variable. We also used the Mann-Whitney U test. An alpha value of 0.05 was determined to have significance (p<0.05).

RESULTS

Inactive patients with FMS have a higher rate of moderate to severe depression (29.1%) and major depression (25%) when compared with active patients. In comparing the depression index between inactive, insufficiently active, and active FMS patients according to the reported weekly volume of PE, we observed differences between inactive and active patients (p=0.035). The level of depression was positively associated with physical inactivity in FMS, and FMS patients with severe depression had 3.45 1.23-9.64) times the likelihood of being inactive than patients without depression or with minimal depression.

LIMITATIONS

The classification of PE does not distinguish between types of PE, or whether differences in activity can have different results in depression.

CONCLUSION

There was an association between PE and lower values of depression in patients with FMS, and the level of depression was positively and significantly associated with physical inactivity.

Functional MRI of the Reserpine-Induced Putative Rat Model of Fibromyalgia Reveals Discriminatory Patterns of Functional Augmentation to Acute Nociceptive Stimuli

Functional neuroimaging, applied to pre-clinical models of chronic pain, offers unique advantages in the drive to discover new treatments for this prevalent and oppressive condition. The high spatial and temporal resolution of fMRI affords detailed mapping of regional pharmacodynamics that underlie mechanisms of pain suppression by new analgesics. Despite evidence supporting the translational relevance of this approach, relatively few studies have investigated fMRI abnormalities in rodent models of chronic pain. In this study, we used fMRI to map the BOLD response in a recently developed putative rat model of fibromyalgia to innocuous and acute nociceptive stimuli by applying a step-wise graded electrical forepaw stimulation paradigm, with comparison to healthy controls. We observed discriminatory functional signatures (p < 0.001) to 2 mA electrical forepaw stimulation, found to be innocuous in the control group. As such, this translational approach provides sensitive and quantitative neural correlates of the underlying chronic disease. The regional patterns of functional augmentation were found to be concordant with previous studies of nociception in the anaesthetised rat brain, supporting the specificity of this approach in the study of altered central pain processing in reserpine induced myalgia. The methodology introduced in this work represents a novel platform for emerging treatment evaluation in highly experimentally controlled conditions.

A low fermentable oligo-di-mono saccharides and polyols(FODMAP) diet reduced pain and improve ddaily life in fibromyalgia patients

Background and aims

Fibromyalgia (FM) is a chronic, rheumatic disease characterized by widespread myofascial pain, of unknown aetiology, having a major impact on quality of life (QOL). Available pharmacotherapy for FM is marginally effective. FM is associated with co-morbidities of gastrointestinal (GI) disorders and Irritable Bowel Syndrome (IBS). There is growing evidence that diets low in FODMAPs, “fermentable oligo-, di- or mono-saccharides and polyols” [Low FODMAP Diet (LFD)], are effective in treating IBS. The aim of this pilot study was to examine the effects of LFDs on symptoms of FM, especially with regard to pain, QOL and GI disorders.

Methods

A longitudinal study using LFD intervention was performed on 38, 51±10 year-old, female patients diagnosed with FM for an average of 10 years, based on ACR (American College of Rheumatology) 2010 criteria. The study was conducted from January through May, 2015, using a four-week, repeated-assessment model, as follows: Moment 0 – introduction of the protocol to participants; Moment 1 – first assessment and delivery of individual LFD dietary plans; Moment 2 – second assessment and reintroduction of FODMAPs; Moment 3 – last assessment and final nutritional counselling. Assessment tools used were the following: RFIQ (Revised Fibromyalgia Impact Questionnaire), FSQ (Fibromyalgia Survey Questionnaire), IBS-SSS (Severity Score System), EQ-5D (Euro-QOL quality of life instrument), and VAS (Visual Analogue Scale). Daily consumption of FODMAPs was quantified based on published food content analyses. Statistical analyses included ANOVA, non-parametric Friedman, t-student and Chi-square tests, using SPSS 22 software.

Results

The mean scores of the 38 participants at the beginning of the study were: FSQ (severity of FM, 0–31) – 22±4.4; RFIQ (0–100) – 65±17; IBS-SSS (0–500) – 275± 101; and EQ-5D (0–100) – 48± 19. Mean adherence to dietary regimens was 86%, confirmed by significant difference in FODMAP intakes (25 g/day vs. 2.5 g/day; p < 0.01). Comparisons between the three moments of assessment showed significant (p < 0.01) declines in scores in VAS, FSQ, and RFIQ scores, in all domains measured. An important improvement was observed with a reduction in the severity of GI symptoms, with 50% reduction in IBS scores to 138±117, following LFD therapy. A significant correlation (r = 0.36; p < 0.05) was found between improvements in FM impact (declined scores) and gastrointestinal scores. There was also a significant correlation (r = 0.65; p < 0.01) between “satisfaction with improvement” after introduction of LFDs and “diet adherence”, with satisfaction of the diet achieving 77% among participants. A significant difference was observed between patients who improved as compared to those that did not improve (Chi-square χ2 = 6.16; p < .05), showing that the probability of improvement, depends on the severity of the RFIQ score.

Conclusions

Implementation of diet therapy involving FODMAP restrictions, in this cohort of FM patients, resulted in a significant reduction in GI disorders and FM symptoms, including pain scores. These results need to be extended in future larger studies on dietary therapy for treatment of FM.

Implications

According to current scientific knowledge, these are the first relevant results found in an intervention with LFD therapy in FM and must be reproduced looking for a future dietetic approach in FM.

Potential drug therapies for the treatment of fibromyalgia

INTRODUCTION

Fibromyalgia (FM) is a common, complex chronic widespread pain condition is characterized by fatigue, sleep disturbance and cognitive dysfunction. Treatment of FM is difficult, requiring both pharmacological and non-pharmacological approaches, with an empiric approach to drug therapy focused toward individual symptoms, particularly pain. The effectiveness of current medications is limited with many patients discontinuing use.

AREAS COVERED

A systemic database search has identified 26 molecular entities as potential emerging drug therapies. Advances in the understanding of the pathophysiology of FM provides clues to targets for new medications. Investigation of bioamine modulation and α2δ ligands and novel targets such as dopamine receptors, NMDA receptors, cannabinoid receptors, melatonin receptors and potassium channels has identified potential drug therapies.

EXPERT OPINION

Modest improvement of health status in patients with FM has been observed with drugs targeting a diverse range of molecular mechanisms. No single drug, however, offered substantial efficacy against all the symptoms characteristic of FM. Identification of new and improved therapies for FM needs to address the heterogeneity of the condition, which suggests existence of patient subgroups, the relationship of central and peripheral aspects of the pathophysiology and a requirement of combination therapy with drugs targeting multiple molecular mechanisms.