Clinical overlap between fibromyalgia and myalgic encephalomyelitis. A systematic review and meta-analysis

Recent research in myalgic encephalomyelitis/chronic fatigue syndrome: an evidence map

Background

Myalgic encephalomyelitis/chronic fatigue syndrome is a chronic condition, classified by the World Health Organization as a nervous system disease, impacting around 17 million people worldwide. Presentation involves persistent fatigue and postexertional malaise (a worsening of symptoms after minimal exertion) and a wide range of other symptoms. Case definitions have historically varied; postexertional malaise is a core diagnostic criterion in current definitions. In 2022, a James Lind Alliance Priority Setting Partnership established research priorities relating to myalgic encephalomyelitis/chronic fatigue syndrome.

Objective(s)

We created a map of myalgic encephalomyelitis/chronic fatigue syndrome evidence (2018-23), showing the volume and key characteristics of recent research in this field. We considered diagnostic criteria and how current research maps against the James Lind Alliance Priority Setting Partnership research priorities.

Methods

Using a predefined protocol, we conducted a comprehensive search of Cochrane, MEDLINE, EMBASE and Cumulative Index to Nursing and Allied Health Literature. We included all English-language research studies published between January 2018 and May 2023. Two reviewers independently applied inclusion criteria with consensus involving additional reviewers. Studies including people diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome using any criteria (including self-report), of any age and in any setting were eligible. Studies with < 10 myalgic encephalomyelitis/chronic fatigue syndrome participants were excluded. Data extraction, coding of topics (involving stakeholder consultation) and methodological quality assessment of systematic reviews (using A MeaSurement Tool to Assess systematic Reviews 2) was conducted independently by two reviewers, with disagreements resolved by a third reviewer. Studies were presented in an evidence map.

Results

Of the 11,278 identified studies, 742 met the selection criteria, but only 639 provided sufficient data for inclusion in the evidence map. These reported data from approximately 610,000 people with myalgic encephalomyelitis/chronic fatigue syndrome. There were 81 systematic reviews, 72 experimental studies, 423 observational studies and 63 studies with other designs. Most studies (94%) were from high-income countries. Reporting of participant details was poor; 16% did not report gender, 74% did not report ethnicity and 81% did not report the severity of myalgic encephalomyelitis/chronic fatigue syndrome. Forty-four per cent of studies used multiple diagnostic criteria, 16% did not specify criteria, 24% used a single criterion not requiring postexertional malaise and 10% used a single criterion requiring postexertional malaise. Most (89%) systematic reviews had a low methodological quality. Five main topics (37 subtopics) were included in the evidence map. Of the 639 studies; 53% addressed the topic 'what is the cause?'; 38% 'what is the problem?'; 26% 'what can we do about it?'; 15% 'diagnosis and assessment'; and 13% other topics, including 'living with myalgic encephalomyelitis/chronic fatigue syndrome'.

Discussion

Studies have been presented in an interactive evidence map according to topic, study design, diagnostic criteria and age. This evidence map should inform decisions about future myalgic encephalomyelitis/chronic fatigue syndrome research.

Limitations

An evidence map does not summarise what the evidence says. Our evidence map only includes studies published in 2018 or later and in English language. Inconsistent reporting and use of diagnostic criteria limit the interpretation of evidence. We assessed the methodological quality of systematic reviews, but not of primary studies.

Conclusions

We have produced an interactive evidence map, summarising myalgic encephalomyelitis/chronic fatigue syndrome research from 2018 to 2023. This evidence map can inform strategic plans for future research. We found some, often limited, evidence addressing every James Lind Alliance Priority Setting Partnership priority; high-quality systematic reviews should inform future studies.

Funding

This article presents independent research funded by the National Institute for Health and Care Research (NIHR) Evidence Synthesis programme as award number NIHR159926.

Long COVID for the Rheumatologist: Current Understanding and Approach to Management

There are estimated tens of millions of individuals throughout the world suffering from a variety of postinfectious sequela following infection with severe acute respiratory syndrome coronavirus 2 also commonly referred to as long coronavirus disease (COVID). Long COVID is providing an opportunity for the field of rheumatology to explore the relationship between similar syndromes including fibromyalgia seen in patients with underlying inflammatory and noninflammatory rheumatic diseases, as well as other postacute infectious sequela and bring our field's traditional skill sets to bear on improving our understanding of these disorders and the care of such patients.

Comparing autonomic nervous system function in patients with functional somatic syndromes, stress-related syndromes and healthy controls

BACKGROUND

The goal of this study was to examine autonomic nervous system function by measuring heart rate (HR), heart rate variability (HRV), skin conductance levels (SCL), and peripheral skin temperature (ST) in response to and during recovery from psychosocial stressors in patients with functional somatic syndromes (FSS; fibromyalgia and/or chronic fatigue syndrome), stress-related syndromes (SRS; overstrain or burn-out), and healthy controls (HC).

METHODS

Patients with FSS (n = 26), patients with SRS (n = 59), and HC (n = 30) went through a standardized psychosocial stress test consisting of a resting phase (120 s), the STROOP color word task (120 s), a mental arithmetic task (120 s) and a stress talk (120 s), each followed by a 120 s recovery period. HR, HRV, SCL, and ST were monitored continuously.

RESULTS

Average HR and SCL were higher, and HRV was lower, in both patient groups compared to HC during rest (0.50 < Cohen's d < 0.97). A larger SC response to psychosocial stress was found in FSS compared to HC (d = 0.71). However, HR increased less during psychosocial stress and showed a smaller reduction during recovery in both patient groups compared to HC (0.68 < d < 0.98). HRV was lower in both patient groups compared to HC during recovery (0.91 < d < 0.98). There were no differences in ST levels or responses between groups.

CONCLUSIONS

Our results indicate a dominance of the sympathetic nervous system in both patient groups compared to controls, suggesting that autonomic nervous system dysfunction is a transdiagnostic feature for stress-related and functional somatic syndromes.

Adrenergic dysfunction in patients with myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia: A systematic review and meta-analysis

BACKGROUND

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia (FM) are comorbid disorders with overlapping symptoms. Research highlights autonomic dysfunction compared to healthy individuals, particularly involving the sympathetic branch. While past reviews focused on neurophysiological assessments, this systematic review summarises biological adrenergic markers, offering deeper insights into the observed sympathetic dysfunction in ME/CFS and FM aiming to identify targetable pathophysiological mechanisms.

METHODS

A systematic search was performed on PubMed, Web of Science, Embase and Scopus. Studies investigating peripheral biological markers of adrenergic function in patients with ME/CFS or FM compared to healthy controls at baseline were included. Meta-analyses were performed using R statistical software.

RESULTS

This meta-analysis of 37 studies, encompassing 543 ME/CFS patients and 651 FM patients, compared with 747 and 447 healthy controls, respectively, revealed elevated adrenaline (SMD = .49 [.31-.67]; Z = 5.29, p < .01) and β1 adrenergic receptor expression (SMD = .79 [.06-1.52]; Z = 2.13; p = .03) in blood of ME/CFS patients at rest. Additionally, patients with ME/CFS had a greater increase in the expression of α2A adrenergic receptor (AR, SMD = .57 [.18-.97]; Z = 2.85, p < .01), β2 AR (SMD = .41 [.02-.81]; Z = 2.04; p = .04) and COMT (SMD = .42 [.03-.81]; Z = 2.11; p = .03) after exercise and an increased response of noradrenaline to an orthostatic test (SMD = .11 [-.47 to -.70]; Z = 2.10; p = .04), both found in blood. FM patients showed no significant differences at baseline but exhibited a diminished adrenaline response to exercise (SMD = -.79 [-1.27 to -.30]; Z = -3.14; p < .01).

CONCLUSION

This systematic review and meta-analysis revealed adrenergic dysfunction mainly in patients with ME/CFS. Higher baseline adrenaline levels and atypical responses to exercise in ME/CFS indicate that sympathetic dysfunction, underscored by adrenergic abnormalities, is more involved in the pathophysiology of ME/CFS rather than FM.

Effectiveness of the SYNCHRONIZE + Brief Intervention in Improving Mediterranean Diet Adherence, Nutritional Quality and Intake Pattern in Persons with Fibromyalgia and Chronic Fatigue Syndrome

BACKGROUND

Multidisciplinary lifestyle interventions are being researched to treat fibromyalgia. However, the impact of nutrition as a key treatment component is little studied. This study aimed to evaluate the effectiveness of the SYNCHRONIZE + lifestyle multidisciplinary intervention in improving adherence to the Mediterranean diet, nutrition quality and dietary intake pattern in persons with fibromyalgia and chronic fatigue syndrome.

METHODS

A pragmatic randomized clinical trial was conducted in primary care. Data were collected using the 17-item energy-restricted Mediterranean Adherence Screener (er-MEDAS), the food frequency questionnaire (sFFQ) and the 24 h recall questionnaire (24 HR), in addition to chrono-nutritional, anthropometric, and body composition data, at baseline and 3-, 6-, and 12- month follow-up visits, and statistically analyzed.

RESULTS

A total of 158 participants were evaluated. Results showed the effectiveness of the intervention in improving adherence to the Mediterranean diet. The adherence depended on the group-time interaction being positive and significant at 3 and 6 months post-intervention in the INT group and on the participant age and educational level. Specifically, the intake of legumes, fruits, vegetables, nuts and blue fish was increased, while the intake of sweets and pastries, butter and cream and red and processed meat was reduced. Furthermore, the intake of chips and candies was also reduced, and the consumption of fermented food (yogurts, cheese, kefir) increased. Thus, general diet quality improved. Interestingly, the intake of key nutrients such as protein and iron increased. Furthermore, the number of night eaters was decreased significantly. Muscle mass index was also improved in the intervention group. These results were maintained in the medium to long term.

CONCLUSION

SYNCHRONIZE + is a brief, low-cost, multidisciplinary intervention effective in improving adherence to the Mediterranean diet and improving nutritional and dietary intake patterns in persons with fibromyalgia and chronic fatigue syndrome. Further evaluation of the effect on quality of life and symptoms is needed.

Overlapping conditions in Long COVID at a multisite academic center

Background

Many patients experience persistent symptoms after COVID-19, a syndrome referred to as Long COVID (LC). The goal of this study was to identify novel new or worsening comorbidities self-reported in patients with LC.

Methods

Patients diagnosed with LC (n = 732) at the Mayo Long COVID Care Clinic in Rochester, Minnesota and Jacksonville, Florida were sent questionnaires to assess the development of new or worsening comorbidities following COVID-19 compared to patients with SARS-CoV-2 that did not develop LC (controls). Both groups were also asked questions screening for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), generalized joint hypermobility (GJH) and orthostatic intolerance. 247 people with LC (33.7%) and 40 controls (50%) responded to the surveys.

Results

In this study LC patients averaged 53 years of age and were predominantly White (95%) women (75%). The greatest prevalence of new or worsening comorbidities following SARS-CoV-2 infection in patients with LC vs. controls reported in this study were pain (94.4% vs. 0%, p < 0.001), neurological (92.4% vs. 15.4%, p < 0.001), sleep (82.8% vs. 5.3%, p < 0.001), skin (69.8% vs. 0%, p < 0.001), and genitourinary (60.6% vs. 25.0%, p = 0.029) issues. 58% of LC patients screened positive for ME/CFS vs. 0% of controls (p < 0.001), 27% positive for GJH compared to 10% of controls (p = 0.026), and a positive average score of 4.0 on orthostatic intolerance vs. 0 (p < 0.001). The majority of LC patients with ME/CFS were women (77%).

Conclusion

We found that comorbidities across 12 surveyed categories were increased in patients following SARS-CoV-2 infection. Our data also support the overlap of LC with ME/CFS, GJH, and orthostatic intolerance. We discuss the pathophysiologic, research, and clinical implications of identifying these conditions with LC.

Systematic review of fatigue severity in ME/CFS patients: insights from randomized controlled trials

BACKGROUND

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating illness medically unexplained, affecting approximately 1% of the global population. Due to the subjective complaint, assessing the exact severity of fatigue is a clinical challenge, thus, this study aimed to produce comprehensive features of fatigue severity in ME/CFS patients.

METHODS

We systematically extracted the data for fatigue levels of participants in randomized controlled trials (RCTs) targeting ME/CFS from PubMed, Cochrane Library, Web of Science, and CINAHL throughout January 31, 2024. We normalized each different measurement to a maximum 100-point scale and performed a meta-analysis to assess fatigue severity by subgroups of age, fatigue domain, intervention, case definition, and assessment tool, respectively.

RESULTS

Among the total of 497 relevant studies, 60 RCTs finally met our eligibility criteria, which included a total of 7088 ME/CFS patients (males 1815, females 4532, and no information 741). The fatigue severity of the whole 7,088 patients was 77.9 (95% CI 74.7-81.0), showing 77.7 (95% CI 74.3-81.0) from 54 RCTs in 6,706 adults and 79.6 (95% CI 69.8-89.3) from 6 RCTs in 382 adolescents. Regarding the domain of fatigue, 'cognitive' (74.2, 95% CI 65.4-83.0) and 'physical' fatigue (74.3, 95% CI 68.3-80.3) were a little higher than 'mental' fatigue (70.1, 95% CI 64.4-75.8). The ME/CFS participants for non-pharmacological intervention (79.1, 95% CI 75.2-83.0) showed a higher fatigue level than those for pharmacological intervention (75.5, 95% CI 70.0-81.0). The fatigue levels of ME/CFS patients varied according to diagnostic criteria and assessment tools adapted in RCTs, likely from 54.2 by ICC (International Consensus Criteria) to 83.6 by Canadian criteria and 54.2 by MFS (Mental Fatigue Scale) to 88.6 by CIS (Checklist Individual Strength), respectively.

CONCLUSIONS

This systematic review firstly produced comprehensive features of fatigue severity in patients with ME/CFS. Our data will provide insights for clinicians in diagnosis, therapeutic assessment, and patient management, as well as for researchers in fatigue-related investigations.

Severe fibromyalgia alleviated by the unique muscle relaxation method of applying low force: A case report

RATIONALE

Fibromyalgia (FM) is characterized by idiopathic persistent chronic pain in the ligaments or musculoskeletal system, and more than half of the patients with FM might have migraine headaches. Direct musculoskeletal intervention could be a non-pharmacological management to relieve symptoms. However, patients with severe FM often have intense pain from only a soft touch, thereby rendering musculoskeletal intervention challenging.

PATIENT CONCERNS

A 47-year-old man had progressing intense pain, and this affected his everyday life. There were no abnormal physical findings on laboratory examination such as levels of complement, antinuclear antibodies, and C-reactive protein, which were within normal limits. Magnetic resonance imaging did not indicate abnormalities.

DIAGNOSES, INTERVENTIONS, AND OUTCOMES

The patient satisfied the American College of Rheumatology criteria. Finally, we made a final diagnosis of fibromyalgia. The therapeutic intervention of Kanshoho, the unique muscle relaxation technique with low force, relieved his pain.

LESSONS

If Kanshoho is carefully applied in a state of hospitalization under surveillance by an experienced physician, it could be a promising muscle relaxation method. Relaxing the trapezius muscle and reducing its intramuscular pressure might be key in treating patients with severe FM. However, it needs elucidation of its mechanism.

Increased Risk of Optic Neuritis in Patients With Fibromyalgia: Nationwide Population-Based Cohort Study in South Korea

PURPOSE

To estimate the risk of incidence of optic neuritis and identify the high-risk group among patients with fibromyalgia (FM).

DESIGN

Population-based cohort study.

METHODS

A nationwide, population-based study was conducted using data from the Korean National Health Claims database from 2012 to 2021. This study included all the patients with FM from the entire South Korean population aged 20-79 years (FM group). Moreover, those with pain but not diagnosed with FM were considered as the non-FM group. A cohort was established by classifying it into the FM and non-FM groups during the recruitment period. A log-rank analysis was used to compare the risk of optic neuritis incidence between the FM group and non-FM group. Cox proportional hazards regression analysis was performed to calculate the adjusted hazard ratio (HR). The cohort was analyzed by stratifying according to age and sex.

RESULTS

The FM and non-FM groups included 479,892 and 479,892 participants, respectively. The incidence rate of optic neuritis was 35.65/100,000 person-years in the FM group; the HR was significantly higher in the FM group than in the non-FM group (HR 2.11, 95% CI 1.84-2.41; P < .001). The mean interval between the onset of FM and incident optic neuritis was 2.4 ± 1.8 years. The risk increased significantly in men aged 60-79 years (HR 3.37, 95% CI 2.54-4.48) and in women aged 20-39 years (HR 2.07, 95% CI 1.38-3.22).

CONCLUSION

We quantified the risk of optic neuritis through a long-term follow-up, which could contribute to understanding the pathophysiology and estimating the general health care burden associated with FM in a practical setting. Great attention should be paid to its risk in older men and younger women.

Exercise Training for Chronic Pain: Available Evidence, Current Recommendations, and Potential Mechanisms

Chronic pain conditions pose a significant global burden of disability, with epidemiological data indicating a rising incidence. Exercise training is commonly recommended as a standalone or complementary approach for managing various chronic pain conditions like low back pain, osteoarthritis, rheumatoid arthritis, fibromyalgia syndrome, and neuropathic pain. Regardless of the specific condition or underlying cause (e.g., autoimmune disease, chronic inflammation), exercise training consistently leads to moderate to large reductions in pain. Moreover, exercise yields numerous benefits beyond pain alleviation, including small-to-moderate improvements in disability, quality of life, and physical function. Despite its efficacy, there is a lack of comprehensive research delineating the optimal intensity, duration, and type of exercise for maximal benefits; however, evidence suggests that sustained engagement in regular exercise or physical activity is necessary to achieve and maintain reductions in both clinical pain intensity ratings and the level that pain interferes with activities of daily living. Additionally, the precise mechanisms through which exercise mitigates pain remain poorly understood and likely vary based on the pathophysiological mechanisms underlying each condition.

Hypothetical framework for post-COVID 19 condition based on a fibromyalgia pathogenetic model

There is a clear clinical overlap between fibromyalgia, myalgic encephalomyelitis, and post-COVID 19 condition. Chronic fatigue, cognitive impairment, and widespread pain characterize these 3 syndromes. A steady line of investigation posits fibromyalgia as stress-evoked sympathetically maintained neuropathic pain syndrome and places dorsal root ganglia dysregulation with the ensuing small fiber neuropathy at the epicenter of fibromyalgia pathogenesis. This article discusses emerging evidence suggesting that similar mechanism may operate in post-COVID 19 condition.

Long COVID as a functional somatic symptom disorder caused by abnormally precise prior expectations during Bayesian perceptual processing: A new hypothesis and implications for pandemic response

This review proposes a model of Long-COVID where the constellation of symptoms are in fact genuinely experienced persistent physical symptoms that are usually functional in nature and therefore potentially reversible, that is, Long-COVID is a somatic symptom disorder. First, we describe what is currently known about Long-COVID in children and adults. Second, we examine reported "Long-Pandemic" effects that create a risk for similar somatic symptoms to develop in non-COVID-19 patients. Third, we describe what was known about somatization and somatic symptom disorder before the COVID-19 pandemic, and suggest that by analogy, Long-COVID may best be conceptualized as one of these disorders, with similar symptoms and predisposing, precipitating, and perpetuating factors. Fourth, we review the phenomenon of mass sociogenic (functional) illness, and the concept of nocebo effects, and suggest that by analogy, Long-COVID is compatible with these descriptions. Fifth, we describe the current theoretical model of the mechanism underlying functional disorders, the Bayesian predictive coding model for perception. This model accounts for moderators that can make symptom inferences functionally inaccurate and therefore can explain how to understand common predisposing, precipitating, and perpetuating factors. Finally, we discuss the implications of this framework for improved public health messaging during a pandemic, with recommendations for the management of Long-COVID symptoms in healthcare systems. We argue that the current public health approach has induced fear of Long-COVID in the population, including from constant messaging about disabling symptoms of Long-COVID and theorizing irreversible tissue damage as the cause of Long-COVID. This has created a self-fulfilling prophecy by inducing the very predisposing, precipitating, and perpetuating factors for the syndrome. Finally, we introduce the term "Pandemic-Response Syndrome" to describe what previously was labeled Long-COVID. This alternative perspective aims to stimulate research and serve as a lesson learned to avoid a repeat performance in the future.

Fibromyalgia - etiology, diagnosis and treatment including perioperative management in patients with fibromyalgia

Fibromyalgia (FM) is considered a multifactorial disorder/syndrome with not fully understood etiology. Chronic generalized pain is the main symptom. A broad spectrum of factors is proposed to explain the etiology. Its multifactorial nature is inherently associated with challenges in diagnosis and therapy. Various evidence of etiology has been evaluated with the aim of establishing a novel therapeutic approach. The main issue in the diagnosis and management is to focus on the evaluation of strict diagnostic criteria to minimize under- and overdiagnosis. Fibromyalgia is a challenge for perioperative management because of the increased risk of possible complications and poorer outcomes, including postoperative pain chronification. The authors have proposed an up-to-date evaluation of perioperative management considering the current guidelines. Multimodal analgesia combined with tailored perioperative care is the most appropriate assessment. Interdisciplinary research with special interest in pain management, including perioperative medicine, seems to be the main theme for the future.

Effectiveness and health benefits of a nutritional, chronobiological and physical exercise primary care intervention in fibromyalgia and chronic fatigue syndrome: SYNCHRONIZE + mixed-methods study protocol

INTRODUCTION

Chronic pain, fatigue and insomnia are classic symptoms of fibromyalgia (FM) and chronic fatigue syndrome (CFS) and seriously affect quality of life. Nutrition and chronobiology are often overlooked in multicomponent approach despite their potential. This study aims to evaluate the effectiveness of a multidisciplinary group intervention based on nutrition, chronobiology, and physical exercise in the improvement of lifestyle and quality of life in FM and CFS.

METHODS

Mixed-methods study based on a randomized clinical trial and qualitative analysis with a descriptive phenomenological approach. The study will be conducted in primary care in Catalonia. The control group will follow the usual clinical practice and the intervention group the usual practice plus the studied intervention (12 hours over 4 days). The intervention based on nutrition, chronobiology and physical exercise will be designed considering participants' opinions as collected in 4 focus groups. To evaluate effectiveness, EuroQol-5D, multidimensional fatigue inventory, VAS pain, Pittsburgh Sleep Quality Index, erMEDAS-17, biological rhythms interview of assessment in neuropsychiatry, REGICOR-Short, FIQR and Hospital Anxiety and Depression Scale questionnaires will be collected at baseline, and at 1, 3, 6, and 12 months post-intervention. Food intake, body composition, resistance and, strength will also be evaluated. The effect size will be calculated using Cohen d and logistic regression models will be used to quantify the impact of the intervention by adjusting for different variables.

DISCUSSION

It expected that the intervention will improve the patients' quality of life, fatigue, pain and insomnia, as well as food and physical exercise habits, providing effectiveness evidence of a new therapy in addressing these syndromes in Primary Heath Care. Improvements in the quality of life will have a positive socioeconomic impact by reducing health expenditure on recurrent medical consultation, medication, complementary medical tests, etc and favor the maintenance of an active working life and productivity.

Autoantibody Correlation Signatures in Fibromyalgia and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Association with Symptom Severity

Recent studies provide some evidence for the contribution of antibody-mediated autoimmune mechanisms to the nature of fibromyalgia (FM) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Much attention was paid to the autoantibodies (AAb) targeting G protein-coupled receptors as natural components of the immune system. However, the natural AAb network is much more extensive, and has not been previously investigated in these disorders. The enzyme immunoassays ELI-Viscero-Test and ELI-Neuro-Test were used to determine changes in serum content of 33 natural AAb to neural, organ-specific and non-tissue-specific autoantigens (a) in 11 ME/CFS patients with comorbid FM; (b) in 11 ME/CFS patients without FM; (c) in 11 healthy controls. Individual AAb profiles and their correlation with some clinical symptoms were analyzed. Both patients with ME/CFS(-)FM and ME/CFS(+)FM were characterized by more frequent and pronounced deviations in the immunoreactivity to GABA-receptors than healthy controls. Although the level of other natural AAb did not differ between study groups, AAb correlation signatures were altered in patients compared to healthy controls. Both in patients and healthy controls the level of natural AAb to various neural and tissue-specific antigens correlated with the severity of fatigue, bodily pain, depression, anxiety, physical and mental health-related quality of life. Notably, widely different correlation patterns were observed between study groups. Findings from this pilot study provide some evidence that the homeostasis of autoimmune relationships, which are possibly a physiological part of our immune system, may be altered in FM and ME/CFS. The correlation of disease-induced perturbations in individual AAb profiles with some clinical symptoms may arise from the immune system's ability to reflect qualitative and quantitative changes in antigenic composition of the body.