Search

This is an open access article under the CC BY license. The etiology of myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is unknown, but involvement of the immune system is one of the proposed underlying mechanisms. Human leukocyte antigen (HLA) associations are hallmarks of immune-mediated and autoimmune diseases. We have previously performed high resolution HLA genotyping and detected associations between ME/CFS and certain HLA class I and class II alleles. However, the HLA complex harbors numerous genes of immunological importance, and there is extensive and complex linkage disequilibrium across the region. In the current study, we aimed to fine map the association signals in the HLA complex by genotyping five additional classical HLA loci and 5,342 SNPs in 427 Norwegian ME/CFS patients, diagnosed according to the Canadian Consensus Criteria, and 480 healthy Norwegian controls. SNP association analysis revealed two distinct and independent association signals (p ≤ 0.001) tagged by rs4711249 in the HLA class I region and rs9275582 in the HLA class II region. Furthermore, the primary association signal in the HLA class II region was located within the HLA-DQ gene region, most likely due to HLA-DQB1, particularly the amino acid position 57 (aspartic acid/alanine) in the peptide binding groove, or an intergenic SNP upstream of HLA-DQB1. In the HLA class I region, the putative causal locus might map outside the classical HLA genes as the association signal spans several genes (DDR1, GTF2H4, VARS2, SFTA2 and DPCR1) with expression levels influenced by the ME/CFS associated SNP genotype. Taken together, our results implicate the involvement of the MHC, and in particular the HLA-DQB1 gene, in ME/CFS. These findings should be replicated in larger cohorts, particularly to verify the putative involvement of HLA-DQB1, a gene important for antigen-presentation to T cells and known to harbor alleles providing the largest risk for well–established autoimmune diseases.

Creatina quinasa; Encefalomielitis miàlgica/síndrome de fatiga crònica; Anàlisis de sang de rutina Creatina quinasa; Encefalomielitis miálgica/síndrome de fatiga crónica; Análisis de sangre de rutina Creatine kinase; Myalgic encephalomyelitis/chronic fatigue syndrome; Routine blood tests There is a lack of research regarding blood tests within individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and between patients and healthy controls. We aimed to compare results of routine blood tests between patients and healthy controls. Data from 149 patients diagnosed with ME/CFS based on clinical and psychiatric evaluation as well as on the DePaul Symptom Questionnaire, and data from 264 healthy controls recruited from blood donors were compared. One-way ANCOVA was conducted to examine differences between ME/CFS patients and healthy controls, adjusting for age and gender. Patients had higher sedimentation rate (mean difference: 1.38, 95% CI: 0.045 to 2.714), leukocytes (mean difference: 0.59, 95% CI: 0.248 to 0.932), lymphocytes (mean difference: 0.27, 95% CI: 0.145 to 0.395), neutrophils (mean difference: 0.34, 95% CI: 0.0 89 to 0.591), monocytes (mean difference: 0.34, 95% CI: 0.309 to 0.371), ferritin (mean difference: 28.13, 95% CI: −1.41 to 57.672), vitamin B12 (mean difference: 83.43, 95% CI: 62.89 to 124.211), calcium (mean difference: 0.02, 95% CI: −0.02 to 0.06), alanine transaminase (mean difference: 3.30, 95% CI: −1.37 to -7.971), low-density lipoproteins (mean difference: 0.45, 95% CI: 0.104 to 0.796), and total proteins (mean difference: 1.53, 95% CI: −0.945 to 4.005) than control subjects. The patients had lower potassium levels (mean difference: 0.11, 95% CI: 0.056 to 0.164), creatinine (mean difference: 2.60, 95% CI: 0.126 to 5.074) and creatine kinase (CK) (mean difference: 37.57, 95% CI: −0.282 to 75.422) compared to the healthy controls. Lower CK and creatinine levels may suggest muscle damage and metabolic abnormalities in ME/CFS patients. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Background and aims Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is challenging to live with, often accompanied by pervasive fatigue and pain, accompanied by decreased quality of life (QoL) as well as anxiety and/or depression. Associations between higher pain, lower QoL and higher anxiety and depression have been shown in patients with various chronic pain disorders. Few studies have however examined such associations in a sample of patients with ME/CFS. The aims of the current study were to examine the impact of pain levels and compare levels of pain, health related QoL, anxiety and depression between patients with ME/CFS and healthy controls. In addition, the study aimed and to examine these relationships within the patient group only. Methods This is a cross-sectional questionnaire based study comparing 87 well-diagnosed patients with ME/CFS with 94 healthy controls. The De Paul Symptom Questionnaire (DSQ), the Medical Outcomes Study Short-Form Surveys (SF-36) and the Hospital Anxiety and Depression Scale (HADS) were used to examine and compare pain, physical function, QoL, anxiety and depression in patients and healthy controls. Further the pain variables were divided into pain total, pain intensity and a pain frequency score for analyses of the above mentioned variables within the patient group only. Results Significantly higher levels of pain, anxiety and depression, and lower levels of QoL were found in the patient group compared with healthy controls. For the patient group alone, pain was significantly associated with lower QoL in terms of physical functioning, bodily pain, general health functioning, vitality and social functioning capacity. In this patient sample, only frequency of joint pain showed significant difference in psychological variables such as depression and anxiety – depression combined. Conclusions ME/CFS patients differ significantly from healthy controls in pain, health related QoL, anxiety and depression. Pain is significantly associated with reduced QoL and overall a lower level of functioning. The relation between pain and anxiety and depression appears less clear. Implications Pain is for many ME/CFS patients associated with reduced physical functioning and reduced QoL. A thorough pain assessment can therefore be essential for clinicians, and subsequent medical pain treatment combined with good pain coping skills may increase functioning level and QoL for these patients. The link between joint pain and psychological factors should also be focused in clinical practice in terms of mapping and counseling. Pain should be further examined to understand the importance it may have for functioning level as reduced function is a main criteria when diagnosing the patients.

The Institute of Medicine (IOM) recently developed clinical criteria for what had been known as chronic fatigue syndrome (CFS). Given the broad nature of the clinical IOM criteria, there is a need for a research definition that would select a more homogenous and impaired group of patients than the IOM clinical criteria. At the present time, it is unclear what will serve as the research definition.The current study focused on a research definition which selected homebound individuals who met the four IOM criteria, excluding medical and psychiatric co-morbidities.Our research criteria were compared to those participants meeting the IOM criteria. Those not meeting either of these criteria sets were placed in a separate group defined by 6 or more months of fatigue. Data analyzed were from the DePaul Symptom Questionnaire and the SF-36. Due to unequal sample sizes and variances, Welch'sUsing a large database of over 1,000 patients from several countries, we found that those meeting a more restrictive research definition were even more impaired and more symptomatic than those meeting criteria for the other two groups.Deciding on a particular research case definition would allow researchers to select more comparable patient samples across settings, and this would represent one of the most significant methodologic advances for this field of study.

This review aimed at determining the prevalence and incidence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in Europe. We conducted a primary search in Scopus, PubMed and Web of Science for publications between 1994 and 15 June 2019 (PROSPERO: CRD42017078688). Additionally, we performed a backward-(reference lists) and forward-(citations) search of the works included in this review. Grey literature was addressed by contacting all members of the European Network on ME/CFS (EUROMENE). Independent reviewers searched, screened and selected studies, extracted data and evaluated the methodological and reporting quality. For prevalence, two studies in adults and one study in adolescents were included. Prevalence ranged from 0.1% to 2.2%. Two studies also included incidence estimates. In conclusion, studies on the prevalence and incidence of ME/CFS in Europe were scarce. Our findings point to the pressing need for well-designed and statistically powered epidemiological studies. To overcome the shortcomings of the current state-of-the-art, EUROMENE recommends that future research is better conducted in the community, reviewing the clinical history of potential cases, obtaining additional objective information (when needed) and using adequate ME/CFS case definitions; namely, the Centers for Disease Control & Prevention−1994, Canadian Consensus Criteria, or Institute of Medicine criteria.

The etiology and pathogenesis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) are unknown, and autoimmunity is one of many proposed underlying mechanisms. Human Leukocyte Antigen (HLA) associations are hallmarks of autoimmune disease, and have not been thoroughly investigated in a large ME/CFS patient cohort. We performed high resolution HLA -A, -B, -C, -DRB1, -DQB1 and -DPB1 genotyping by next generation sequencing in 426 adult, Norwegian ME/CFS patients, diagnosed according to the Canadian Consensus Criteria. HLA associations were assessed by comparing to 4511 healthy and ethnically matched controls. Clinical information was collected through questionnaires completed by patients or relatives. We discovered two independent HLA associations, tagged by the alleles HLA-C*07:04 (OR 2.1 [95% CI 1.4–3.1]) and HLA-DQB1*03:03 (OR 1.5 [95% CI 1.1–2.0]). These alleles were carried by 7.7% and 12.7% of ME/CFS patients, respectively. The proportion of individuals carrying one or both of these alleles was 19.2% in the patient group and 12.2% in the control group (OR 1.7 [95% CI 1.3–2.2], pnc = 0.00003). ME/CFS is a complex disease, potentially with a substantial heterogeneity. We report novel HLA associations pointing toward the involvement of the immune system in ME/CFS pathogenesis.

Objectives: Lasting, unexplained and high levels of pain may cause anxiety in patients with chronic fatigue syndrome. The objectives of the current study were to test assumptions of the association between pain and anxiety in patients diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and to clarify the role of depression in this relationship. Methods: Data were collected from 664 participants (age 18-65 years) with 133 ME/CFS patients and 201 healthy controls from Norway and 330 CFS patients from Spain. Binary logistic regression model was applied to test relationships between the included variables in the samples. Results: Both pain and depression made significant direct contributions to the level of anxiety. The strongest risk for higher levels of anxiety was the combination of high levels of depression and high levels of pain in the overall sample (OR = 49.70; P Conclusions: It was the combination of high pain levels and high levels of depression that to the greatest extent increased the risk of anxiety in patients with CFS/ME. Whatever diagnostic criterion that is applied, anxiety and depression should be mandatory to assess in the clinical assessments performed for diagnosing the ME/CFS. Approaches addressing anxiety-related pain and treatment of depression should be warranted.

Objective: To evaluate the effectiveness of a group-based self-management program for people with chronic fatigue syndrome. Design: A randomized controlled trial. Setting: Four mid-sized towns in southern Norway and two suburbs of Oslo. Subjects: A total of 137 adults with chronic fatigue syndrome. Intervention: A self-management program including eight biweekly meetings of 2.5 hours duration. The control group received usual care. Main measures: Primary outcome measure: Medical Outcomes Study-Short Form-36 physical functioning subscale. Secondary outcome measures: Fatigue severity scale, self-efficacy scale, physical and mental component summary of the Short Form-36, and the illness cognition questionnaire (acceptance subscale). Assessments were performed at baseline, and at six-month and one-year follow-ups. Results: At the six-month follow-up, a significant difference between the two groups was found concerning fatigue severity ( p = 0.039) in favor of the control group, and concerning self-efficacy in favor of the intervention group ( p = 0.039). These significant differences were not sustained at the one-year follow-up. No significant differences were found between the groups concerning physical functioning, acceptance, and health status at any of the measure points. The drop-out rate was 13.9% and the median number of sessions attended was seven (out of eight). Conclusions: The evaluated self-management program did not have any sustained effect, as compared with receiving usual care.

Myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) have case definitions with varying criteria, but almost all criteria require an individual to have a substantial reduction in activity level. Unfortunately, a consensus has not been reached regarding what constitutes substantial reductions. One measure that has been used to measure substantial reduction is the Medical Outcomes Study Short Form-36 Health Survey (SF-36).[1].The current study examined the relationship between the SF-36, a measure of current functioning, and a self-report measure of the percent reduction in hours spent on activities.Findings indicated that select subscales of the SF-36 accurately measure significant reductions in functioning. Further, this measure significantly differentiates patients from controls.Determining what constitutes a significant reduction in activity is difficult because it is subjective to the individual. However, certain subscales of the SF-36 could provide a uniform way to accurately measure and define substantial reductions in functioning.

Objectives The objective of this study was to examine individuals with myalgic encephalomyelitis and chronic fatigue syndrome who are confined to their homes due to severe symptomatology. The existing literature fails to address differences between this group, and less severe, nonhousebound patient populations. Methods Participants completed the DePaul Symptom Questionnaire, a measure of myalgic encephalomyelitis and chronic fatigue syndrome symptomology, and the SF-36, a measure of health impact on physical/mental functioning. ANOVAs and, where appropriate, MANCOVAS were used to compare housebound and nonhousebound patients with myalgic encephalomyelitis and chronic fatigue syndrome across areas of functioning, symptomatology, and illness onset characteristics. Results Findings indicated that the housebound group represented one quarter of the sample, and were significantly more impaired with regards to physical functioning, bodily pain, vitality, social functioning, fatigue, postexertional malaise, sleep, pain, neurocognitive, autonomic, neuroendocrine, and immune functioning compared to individuals who were not housebound. Discussion Findings indicated that housebound patients have more impairment on functional and symptom outcomes compared to those who were not housebound. Understanding the differences between housebound and not housebound groups holds implications for physicians and researchers as they develop interventions intended for patients who are most severely affected by this chronic illness.

Background: Diagnostic assessment of chronic fatigue syndrome (CFS) and myalgic encephalomyelitis (ME) is largely based on a two part process; screening patients who might meet criteria and following up this assessment with physicians’ clinical evaluation of a range of inclusionary symptoms and exclusionary illnesses. Purpose: The aim was to assess how well the DePaul Symptom Questionnaire (DSQ) screened for patients who were ultimately diagnosed by physicians using the Canadian Consensus Criteria (CCC). Methods: Sixty-four patients referred for evaluation of possible CFS or ME were screened initially using the DSQ, and then evaluated and subsequently diagnosed by physicians. To assess the consistency between the self-report DSQ and the physicians’ diagnosis, sensitivity and specificity as well as predictive values were calculated. Results: The DSQ identified 60 and the physicians identified 56 as having a CCC diagnosis. The overall agreement between the two ratings on the diagnostic assessment part was m...

There has been considerable controversy regarding how to name and define the illnesses known as myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS). The IOM report has proposed a new clinical criteria and name for this illness, but aspects of these recommendations have been scrutinized by patients and scientists.It is possible that both empiric and consensus approaches could be used to help settle some of these diagnostic challenges. Using patient samples collected in the United States, Great Britain, and Norway (N=556), the current study attempted to categorize patients using more general as well as more restricted case definitions.Overall, the outcomes suggest that there might be four groupings of patients, with the broadest category involving those with chronic fatigue (N=62), defined by 6 or more months of fatigue which can be cannot be explained by medical or psychiatric conditions. A second category involves those patients that have chronic fatigue that can be explained by a medical or psychiatric condition (N=47). A third category involves more specific criteria that have been posited both by the IOM report, a Canadian Clinical Case criteria, a ME-ICC criteria and a more empiric approach. These efforts have specified domains of substantial reductions of activity, post-exertional malaise, neurocognitive impairment, and sleep dysfunction (N=346). Patients with these characteristics were more functionally impaired than those meeting just chronic fatigue criteria,The advantages of using such empirical and consensus approaches to develop reliable classification and diagnostic efforts are discussed.

The Institute of Medicine has recommended a change in the name and criteria for Chronic Fatigue Syndrome (CFS), renaming the illness Systemic Exertion Intolerance Disease (SEID). The new SEID case definition requires substantial reductions or impairments in the ability to engage in pre-illness activities, unrefreshing sleep, post-exertional malaise, and either cognitive impairment or orthostatic intolerance.In the current study, samples were generated through several different methods and were used to compare this new case definition to previous case definitions for CFS, Myalgic Encephalomyelitis (ME-ICC), Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), as well as a case definition developed through empirical methods.We used a cross-sectional design with samples from tertiary care settings, a biobank sample, and other forums. 796 patients from the US, Great Britain, and Norway completed the DePaul Symptom Questionnaire.Findings indicated that the SEID criteria identified 88% of participants in the samples analyzed, which is comparable to the 92% that met the Fukuda criteria. The SEID case definition was compared to a four item empiric criteria, and findings indicated that the four item empiric criteria identified a smaller, more functionally limited and symptomatic group of patients.The recently developed SEID criteria appears to identify a group comparable in size to the Fukuda et al. criteria, but a larger group of patients than the Canadian ME/CFS and ME criteria, and selects more patients who have less impairment and fewer symptoms than a four item empiric criteria.

Background: Interventions that potentially improve coping with chronic fatigue syndrome (CFS) are important for patients, clinicians, and researchers. Purpose: To identify factors experienced by patients to promote coping with CFS and to provide recommendations for adequate interventions in this patient group. Methods: A systematic review of qualitative studies was performed. Structured searches were conducted in major scientific databases. Two reviewers independently performed the study selection and assessment. Meta-ethnography was applied to review and synthesise the studies. The analysis provided key concepts that could be aggregated using second-order interpretations. Results: Fifteen studies were included. Findings suggested that coping strategies, including activity management and the use of cognitive and emotional strategies, and psychological processes, such as acceptance and the rebuilding of identities and lives, may promote coping with CFS. The use of adequate coping strategies appeared to be ...

Background: Since the publication of the CFS case definition, there have been a number of other criteria proposed including the Canadian Consensus Criteria and the Myalgic Encephalomyelitis: International Consensus Criteria. Purpose: The current study compared these domains that were developed through consensus methods to one obtained through more empirical approaches using factor analysis. Methods: Using data mining, we compared and contrasted fundamental features of consensus-based criteria versus empirical latent factors. In general, these approaches found the domain of fatigue/post-exertional malaise as best differentiating patients from controls. Results: Findings indicated that the Fukuda et al. criteria had the worst sensitivity and specificity. Conclusions: These outcomes might help both theorists and researchers better determine which fundamental domains to be used for the case definition.

The Institute of Medicine (IOM) recently developed clinical criteria for chronic fatigue syndrome (CFS). There might be additional criteria that could select a more homogenous and impaired group of patients, particularly those with pain. The current study focused on criteria which involved meeting the four IOM criteria, excluding medical and psychiatric co-morbidities, along with having fibromyalgia (FM). Findings indicated that those meeting the IOM clinical criteria plus FM were more impaired on a wide variety of symptoms and functional areas than those meeting on the IOM criteria or those with just 6 months of fatigue. The implications of using such research criteria are discussed.

The aim of this study was to elicit participants' experiences with a multidisciplinary patient education programme and their views regarding the usefulness of the programme. Focus group interviews were conducted with 10 participants immediately and nine months following participation in the programme and analysed using thematic analysis. Initially, the participants experienced confusion and insecurity regarding coping with the illness. Participation in the programme appeared to promote understanding, acceptance and coping through gaining greater knowledge, learning coping strategies and exchanging experiences, as well as receiving understanding and acceptance. Thus, the programme was experienced to be a beneficial intervention. However, the participants expressed a need for more guidance or follow-up to maintain the practice of coping strategies for better coping with their illness.

Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is a common and severe disease with a considerable social and economic impact. So far, the etiology is not known, and neither a diagnostic marker nor licensed treatments are available yet. The EUROMENE network of European researchers and clinicians aims to promote cooperation and advance research on ME/CFS. To improve diagnosis and facilitate the analysis of clinical trials surrogate markers are urgently needed. As a first step for developing such biomarkers for clinical use a database of active biomarker research in Europe was established called the ME/CFS EUROMENE Biomarker Landscape project and the results are presented in this review. Further we suggest strategies to improve biomarker development and encourage researchers to take these into consideration for designing and reporting biomarker studies.

Chronic fatigue syndrome (CFS) is a debilitating illness, but it is unclear if patient age and illness duration might affect symptoms and functioning of patients. In the current study, participants were categorized into four groups based upon age (under or over age 55) and illness duration (more or less than 10 years). The groups were compared on functioning and symptoms. Findings indicated that those who were older with a longer illness duration had significantly higher levels of mental health functioning than those who were younger with a shorter or longer illness duration and the older group with a shorter illness duration. The results suggest that older patients with an illness duration of over 10 years have significantly higher levels of mental health functioning than the three other groups. For symptoms, the younger/longer illness duration group had significantly worse immune and autonomic domains than the older/longer illness group. In addition, the younger patients with a longer illness duration displayed greater autonomic and immune symptoms in comparison to the older group with a longer illness duration. These findings suggest that both age and illness duration need to be considered when trying to understand the influence of these factors on patients.

IntroductionMyalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic disease involving central nervous system and immune system disorders, as well as cardiovascular abnormalities. ME/CFS is characterised by severe chronic fatigue lasting for at least 6 months, including clinical symptoms such as tender cervical or axillary lymph nodes, muscle pain, joint pain without swelling or redness, post-exertional malaise for more than 24 hours and unrefreshing sleep. Studies on the epidemiology of ME/CFS in Europe only include single countries and, therefore, the prevalence and incidence of ME/CFS in Europe (as a whole) is unknown. One of the purposes of the European Network on ME/CFS (EUROMENE; European Union-funded COST Action; Reference number: 15111) is to address this gap in knowledge. We will systematically review the literature reporting figures from European countries to provide a robust summary and identify new challenges.Methods and analysisWe will systematically search the literature databases Scopus, PubMed and Web of Science for studies published in the last 10 years (ie, after 2007). No language restriction will be applied. Two independent reviewers will search, screen and select studies as well as extract data about their main characteristics and evaluate their methodological and reporting quality. When disagreements emerge, the reviewers will discuss to reach a consensus. We plan to produce a narrative summary of our findings as we anticipate that studies are scarce and heterogeneous. The possibility of performing meta-analyses will be discussed in a EUROMENE meeting.Ethics and disseminationEthical approval is not required as only publicly available data will be included. Findings will be described in EUROMENE reports, published in peer-reviewed journal(s) and presented at conferences. The findings will be also communicated to policy-makers, healthcare providers, people with ME/CFS and other sections of society through regular channels including the mass-media.PROSPERO registration numberCRD42017078688

The objective of the study was to analyze the relationships between Pain Readiness to Change, weekly measures of positive and negative affect and pain over eight subsequent weeks in patients with rheumatoid arthritis (RA). Factor analysis based on data from three different samples of patients with rheumatic diseases and other chronic pain conditions suggested a three factor solution for the Norwegian version of the Pain Stages of Change questionnaire (PSOCQ) representing Precontemplation, Contemplation, and Action/Maintenance (ACT) stages from the original Transtheoretical Model. Multilevel analyses on the weekly assessed data from a sub sample of 40 patients with RA revealed that higher levels of Pain Readiness to Change represented by high ACT scores were associated with more positive affect from week to week while no association was found between Readiness to Change and weekly pain. However, there was an interaction effect between Pain Readiness to Change and weekly positive affect on weekly pain, indicating that those persons having a higher level of Readiness to Change reported less pain in weeks when they also experienced increased positive affect. This may imply that a combination of cognitive factors and positive affect is most effective in relation to pain reduction. Results encourage continued investigation of apparent interactions between chronic pain, affect, and pain self-management.

This study is evaluated what patients with rheumatic disease perceive as important in their medical encounters. We interviewed two groups of patients: one with a well-defined inflammatory condition (rheumatoid arthritis (RA) or ankylosing spondylitis) (n = 12) and one with non-inflammatory widespread chronic pain such as fibromyalgia (n = 14). Both groups focused on their relationship to their doctor. Two central themes emerged as of importance: 'to be seen' and 'to be believed'. However, these themes had different connotations for the two groups. For the patients with inflammatory conditions, 'to be seen' implied being seen as an individual and not as a mere diagnosis, and 'to be believed' as far as pain and suffering were concerned. For patients with non-inflammatory chronic pain 'to be seen' and 'to be believed' primarily implied being able to obtain a useful somatic diagnosis. Practical implications of these findings are discussed.

The present study attempted to identify critical symptom domains of individuals with Myalgic Encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Using patient and control samples collected in the United States, Great Britain, and Norway, exploratory factor analysis (EFA) was used to establish the underlying factor structure of ME and CFS symptoms. The EFA suggested a four-factor solution: post-exertional malaise, cognitive dysfunction, sleep difficulties, and a combined factor consisting of neuroendocrine, autonomic, and immune dysfunction symptoms. The use of empirical methods could help better understand the fundamental symptom domains of this illness.

We need to know more of what kind of mechanisms is involved when stress or pain is prevented or reduced and also why some people maintain mental health and well-being in spite of aversive conditions. The impact of positive affect was investigated in patients with a chronic painful disease such as rheumatoid arthritis. Main findings from analyses reported in two different papers are presented in this chapter. The dataset applied in both papers consisted of 43 participants that were interviewed by telephone for eight subsequent weeks. Multilevel modeling was applied to analyze the data. Results revealed that positive affect was a source of resilience in the stress-negative affect relationship, and also that for those patients with higher level of readiness to change, positive affect was related to less pain. Results indicated that positive emotions may be contributing factors in the process of recovery for patients with rheumatoid arthritis.

The purpose of this study is to examine positive affect (PA) as a factor of resilience in the relationships between pain and negative affect (NA) in a sample of patients with rheumatoid arthritis.Forty-three patients (30 women; mean age, 57 years) were interviewed weekly by telephone for 8 weeks. Multilevel modeling was applied to study the within-week relationships among the variables.There was a Pain x PA interaction effect on NA (beta=-0.05, P.01) indicating a weaker relationship between pain and NA in weeks with more PA. Pain (beta=0.37, P.002), interpersonal stress (beta=2.42, P.001), depression (beta=0.26, P.01), average perceived stress (beta=10.80, P.001), and also weekly PA (beta=-0.1, P.01) had a main effect upon NA.Positive affect is most influential in reducing NA during weeks of higher pain and may be a factor of resilience, helping patients experiencing pain fluctuations as less distressful than at lower levels of PA.