A systematic review of chronic fatigue, its syndromes and ethnicity: prevalence, severity, co-morbidity and coping

Abstract:

BACKGROUND: Chronic Fatigue Syndrome (CFS) is characterized by unexplained fatigue that lasts for at least 6 months alongside a constellation of other symptoms. CFS was historically thought to be most common among White women of higher socio-economic status. However, some recent studies in the USA suggest that the prevalence is actually higher in some minority ethnic groups. If there are convincing differences in prevalence and risk factors across all or some ethnic groups, investigating the causes of these can help unravel the pathophysiology of CFS.

METHODS: A systematic review was conducted to explore the relationship between fatigue, chronic fatigue (CF–fatigue lasting for 6 months), CFS and ethnicity. Studies were population-based and health service-based. Meta-analysis was also conducted to examine the population prevalence of CF and CFS across ethnic groups.

RESULTS: Meta-analysis showed that compared with the White American majority, African Americans and Native Americans have a higher risk of CFS [Odds Ratio (OR) 2.95, 95% confidence interval (CI): 0.69-10.4; OR = 11.5, CI: 1.1-56.4, respectively] and CF (OR = 1.56, CI: 1.03-2.24; OR = 3.28, CI: 1.63-5.88, respectively). Minority ethnic groups with CF and CFS experience more severe symptoms and may be more likely to use religion, denial and behavioural disengagement to cope with their condition compared with the White majority.

CONCLUSIONS: Although available studies and data are limited, it does appear that some ethnic minority groups are more likely to suffer from CF and CFS compared with White people. Ethnic minority status alone is insufficient to explain ethnic variation of prevalence. Psychosocial risk factors found in high-risk groups and ethnicity warrant further investigation to improve our understanding of aetiology and the management of this complex condition.

 

Source: Dinos S, Khoshaba B, Ashby D, White PD, Nazroo J, Wessely S, Bhui KS. A systematic review of chronic fatigue, its syndromes and ethnicity: prevalence, severity, co-morbidity and coping. Int J Epidemiol. 2009 Dec;38(6):1554-70. doi: 10.1093/ije/dyp147. Epub 2009 Apr 6. http://ije.oxfordjournals.org/content/38/6/1554.long (Full article)

 

Chronic fatigue syndrome

Comment in: Graded exercise for chronic fatigue syndrome: too soon to dismiss reports of adverse reactions. [J Rehabil Med. 2010]

Comment on: Chronic fatigue syndrome: an approach combining self-management with graded exercise to avoid exacerbations. [J Rehabil Med. 2008]

 

Sir, We read with interest the special report by Nijs et al. (1), entitled “Chronic fatigue syndrome: an approach combining self-management with graded exercise to avoid exacerbations”. The paper proposes to provide an integrated model for graded exercise therapy (GET) in patients with chronic fatigue syndrome (CFS).
The authors state that current GET programmes for people with CFS exacerbate symptoms. This is a familiar and mistaken criticism of GET, often quoted from the 2001 Action for myaligic encephalomyelitis (ME) (AfME) survey, which reported that 50% of patients with CFS/ME who received graded exercise felt worse (2). A follow-up survey reported that, in many cases, exercise was being undertaken independently, without the supervision of a therapist trained to deliver GET to patients with CFS (3). In other words, it was not GET.

You can read the rest of this comment here: https://www.medicaljournals.se/jrm/content/abstract/10.2340/16501977-0261

 

Source: Clark LV, White PD. Chronic fatigue syndrome. J Rehabil Med. 2008 Nov;40(10):882-3; author reply 883-5. doi: 10.2340/16501977-0261. https://www.medicaljournals.se/jrm/content/abstract/10.2340/16501977-0261

 

Chronic fatigue syndrome or myalgic encephalomyelitis

Comment on: Diagnosis and management of chronic fatigue syndrome or myalgic encephalomyelitis (or encephalopathy): summary of NICE guidance. [BMJ. 2007]

The uncertainty inherent in making a diagnosis of chronic fatigue syndrome (CFS) is reflected by the variety of names (such as myalgic encephalomyelitis; ME) it has been given. The names reflect the hope that such labels can impose some certainty where little exists. Many doctors are reluctant to make a diagnosis of CFS, with half not even believing it exists.1 The consequences of this uncertainty and reluctance have been that patients hear mixed messages and often receive poor, if any, care.2 It is therefore a welcome relief that the National Institute for Health and Clinical Excellence (NICE) has just published clinical guidelines on the diagnosis and management of this disease.3 In this week’s BMJ, Baker and Shaw summarise the guidelines.4

You can read the rest of this comment here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1962896/

 

Source: White P, Murphy M, Moss J, Armstrong G, Spencer P. Chronic fatigue syndrome or myalgic encephalomyelitis. BMJ. 2007 Sep 1;335(7617):411-2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1962896/ (Full article)

 

How common is chronic fatigue syndrome; how long is a piece of string?

Comment on: Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia. [Popul Health Metr. 2007]

One of the most difficult tasks in medicine is to accurately measure how common illnesses are. Why do we do it? Justifications include being able to plan health care and public health priorities, as well as highlighting specific diseases for extra funding for both health care and research. Yet the jobbing physician at the sharp edge of clinical practice cares little about the exact prevalence of a disease or illness, since this is all too obvious from the frequency of the problems presented by patients who come through the door.

You can read the rest of this comment here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1904177/

 

Source: White PD. How common is chronic fatigue syndrome; how long is a piece of string? Popul Health Metr. 2007 Jun 8;5:6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1904177/ (Full article)

 

Is a full recovery possible after cognitive behavioural therapy for chronic fatigue syndrome?

Abstract:

BACKGROUND: Cognitive behavioural therapy (CBT) for chronic fatigue syndrome (CFS) leads to a decrease in symptoms and disabilities. There is controversy about the nature of the change following treatment; some suggest that patients improve by learning to adapt to a chronic condition, others think that recovery is possible. The objective of this study was to find out whether recovery from CFS is possible after CBT.

METHODS: The outcome of a cohort of 96 patients treated for CFS with CBT was studied. The definition of recovery was based on the absence of the criteria for CFS set up by the Center for Disease Control (CDC), but also took into account the perception of the patients’ fatigue and their own health. Data from healthy population norms were used in calculating conservative thresholds for recovery.

RESULTS: After treatment, 69% of the patients no longer met the CDC criteria for CFS. The percentage of recovered patients depended on the criteria used for recovery. Using the most comprehensive definition of recovery, 23% of the patients fully recovered. Fewer patients with a co-morbid medical condition recovered.

CONCLUSION: Significant improvement following CBT is probable and a full recovery is possible. Sharing this information with patients can raise the expectations of the treatment, which may enhance outcomes without raising false hopes.

Copyright 2007 S. Karger AG, Basel.

 

Source: Knoop H, Bleijenberg G, Gielissen MF, van der Meer JW, White PD. Is a full recovery possible after cognitive behavioural therapy for chronic fatigue syndrome? Psychother Psychosom. 2007;76(3):171-6. https://www.ncbi.nlm.nih.gov/pubmed/17426416

 

Protocol for the PACE trial: a randomised controlled trial of adaptive pacing, cognitive behaviour therapy, and graded exercise, as supplements to standardised specialist medical care versus standardised specialist medical care alone for patients with the chronic fatigue syndrome/myalgic encephalomyelitis or encephalopathy

Abstract:

BACKGROUND: Chronic fatigue syndrome (CFS, also called myalgic encephalomyelitis /encephalopathy or ME) is a debilitating condition with no known cause or cure. Improvement may occur with medical care and additional therapies of pacing, cognitive behavioural therapy and graded exercise therapy. The latter two therapies have been found to be efficacious in small trials, but patient organisations surveys have reported adverse effects. Although pacing has been advocated by patient organisations, it lacks empirical support. Specialist medical care is commonly provided but its efficacy when given alone is not established. This trial compares the efficacy of the additional therapies when added to specialist medical care against specialist medical care alone.

METHODS: 600 patients, who meet operationalised diagnostic criteria for CFS, will be recruited from secondary care into a randomised trial of four treatments, stratified by current co morbid depressive episode and different CFS/ME criteria. The four treatments are standardised specialist medical care either given alone, or with adaptive pacing therapy or cognitive behaviour therapy or graded exercise therapy. Supplementary therapies will involve fourteen sessions over 23 weeks and a booster session at 36 weeks. Outcome will be assessed at 12, 24, and 52 weeks after randomisation. Two primary outcomes of self-rated fatigue and physical function will assess differential effects of each treatment on these measures. Secondary outcomes include adverse events and reactions, subjective measures of symptoms, mood, sleep and function and objective measures of physical activity, fitness, cost-effectiveness and cost-utility. The primary analysis will be based on intention to treat and will use logistic regression models to compare treatments. Secondary outcomes will be analysed by repeated measures analysis of variance with a linear mixed model. All analyses will allow for stratification factors. Mediators and moderators will be explored using multiple linear and logistic regression techniques with interactive terms, with the sample split into two to allow validation of the initial models. Economic analyses will incorporate sensitivity measures.

DISCUSSION: The results of the trial will provide information about the benefits and adverse effects of these treatments, their cost-effectiveness and cost-utility, the process of clinical improvement and the predictors of efficacy.

 

Source: White PD, Sharpe MC, Chalder T, DeCesare JC, Walwyn R; PACE trial group. Protocol for the PACE trial: a randomised controlled trial of adaptive pacing, cognitive behaviour therapy, and graded exercise, as supplements to standardised specialist medical care versus standardised specialist medical care alone for patients with the chronic fatigue syndrome/myalgic encephalomyelitis or encephalopathy. BMC Neurol. 2007 Mar 8;7:6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2147058/

 

A case control study of premorbid and currently reported physical activity levels in chronic fatigue syndrome

Abstract:

BACKGROUND: Patients with chronic fatigue syndrome typically report high levels of physical activity before becoming ill. Few studies have examined premorbid and current activity levels in chronically fatigued patients.

METHODS: In a case-control study, 33 patients with chronic, unexplained, disabling fatigue attending a university-based clinic specializing in fatigue were compared to 33 healthy, age- and sex-matched controls. Patients rated their activity levels before their illness and currently, using scales designed for this purpose. Controls reported their level of activity of 2 years previously and currently. Chi-square analyses, Student’s t tests, and Wilcoxon signed rank tests were used in pair matched analyses.

RESULTS: Compared to healthy controls, patients with chronic, unexplained fatigue rated themselves as more active before their illness (p < or = 0.001) and less active currently (p < or = 0.001). The patients also reported they currently stood or walked less than the controls (median [inter-quartile range] = 4 2345 versus 9 [7.5-12] hours, p < or = 0.001), and spent more time reclining (median [inter-quartile range] = 12 10111213141516 versus 8 [8-9.5] hours, p < or = 0.001). These differences remained significant for the subset of patients who met strict criteria for chronic fatigue syndrome or fibromyalgia.

CONCLUSION: Patients with chronic, unexplained, disabling fatigue reported being more active before becoming ill than healthy controls. This finding could be explained by greater premorbid activity levels that could predispose to illness, or by an overestimation of previous activity. Either possibility could influence patients’ perceptions of their current activity levels and their judgments of recovery. Perceived activity should be addressed as part of management of the illness.

 

Source: Smith WR, White PD, Buchwald D. A case control study of premorbid and currently reported physical activity levels in chronic fatigue syndrome. BMC Psychiatry. 2006 Nov 13;6:53. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1647270/ (Full article)

 

Polymorphisms in genes regulating the HPA axis associated with empirically delineated classes of unexplained chronic fatigue

Abstract:

Chronic fatigue syndrome (CFS) is characterized by persistent or relapsing fatigue that is not alleviated by rest, causes substantial reduction in activities and is accompanied by a variety of symptoms. Its unknown etiology may reflect that CFS is heterogeneous. Latent class analyses of symptoms and physiological systems were used to delineate subgroups within a population-based sample of fatigued and nonfatigued subjects [1] . This study examined whether genetic differences underlie the individual subgroups of the latent class solution.

Polymorphisms in 11 candidate genes related to both hypothalamic-pituitary-adrenal (HPA) axis function and mood-related neurotransmitter systems were evaluated by comparing each of the five ill classes (Class 1, n = 33; Class 3, n = 22; Class 4, n = 22; Class 5, n = 17; Class 6, n = 11) of fatigued subjects with subjects defined as well (Class 2, n = 35). Of the five classes of subjects with unexplained fatigue, three classes were distinguished by gene polymorphsims involved in either HPA axis function or neurotransmitter systems, including proopiomelanocortin (POMC), nuclear receptor subfamily 3, group C, member 1 (NR3C1), monoamine oxidase A (MAOA), monoamine oxidase B (MAOB), and tryptophan hydroxylase 2 (TPH2). These data support the hypothesis that medically unexplained chronic fatigue is heterogeneous and presents preliminary evidence of the genetic mechanisms underlying some of the putative conditions.

 

Source: Smith AK, White PD, Aslakson E, Vollmer-Conna U, Rajeevan MS. Polymorphisms in genes regulating the HPA axis associated with empirically delineated classes of unexplained chronic fatigue. Pharmacogenomics. 2006 Apr;7(3):387-94. https://www.ncbi.nlm.nih.gov/pubmed/16610949

 

Gene expression profile of empirically delineated classes of unexplained chronic fatigue

Abstract:

OBJECTIVES: To identify the underlying gene expression profiles of unexplained chronic fatigue subjects classified into five or six class solutions by principal component (PCA) and latent class analyses (LCA).

METHODS: Microarray expression data were available for 15,315 genes and 111 female subjects enrolled from a population-based study on chronic fatigue syndrome. Algorithms were developed to assign gene scores and threshold values that signified the contribution of each gene to discriminate the multiclasses in each LCA solution. Unsupervised dimensionality reduction was first used to remove noise or otherwise uninformative gene combinations, followed by supervised dimensionality reduction to isolate gene combinations that best separate the classes.

RESULTS: The authors’ gene score and threshold algorithms identified 32 and 26 genes capable of discriminating the five and six multiclass solutions, respectively. Pair-wise comparisons suggested that some genes (zinc finger protein 350 [ZNF350], solute carrier family 1, member 6 [SLC1A6], F-box protein 7 [FBX07] and vacuole 14 protein homolog [VAC14]) distinguished most classes of fatigued subjects from healthy subjects, whereas others (patched homolog 2 [PTCH2] and T-cell leukemia/lymphoma [TCL1A]) differentiated specific fatigue classes.

CONCLUSION: A computational approach was developed for general use to identify discriminatory genes in any multiclass problem. Using this approach, differences in gene expression were found to discriminate some classes of unexplained chronic fatigue, particularly one termed interoception.

 

Source: Carmel L, Efroni S, White PD, Aslakson E, Vollmer-Conna U, Rajeevan MS. Gene expression profile of empirically delineated classes of unexplained chronic fatigue. Pharmacogenomics. 2006 Apr;7(3):375-86. https://www.ncbi.nlm.nih.gov/pubmed/16610948

 

The validity of an empirical delineation of heterogeneity in chronic unexplained fatigue

Abstract:

OBJECTIVES: To validate a latent class structure derived empirically from a clinical data set obtained from persons with chronic medically unexplained fatigue.

METHODS: The strategies utilized in this validation study included: recalculating latent class analysis (LCA) results varying random seeds and the number of initial random starting sets; recalculating LCA results by substituting alternate variables to demonstrate a robust solution; determining the statistical significance of between-class differences on disability, fatigue and demographic measures omitted from the data set used for LCA; cross-classifying class membership using established Centers for Disease Control and Prevention (CDC) research criteria for chronic fatigue syndrome (CFS) to compare the relative proportions of subjects designated CFS, chronic fatigue (not CFS) or healthy controls captured by the latent classes.

RESULTS: Recalculation of results and substitution of variables for low-loading variables demonstrated a robust LCA result. Highly significant between-class differences were confirmed between Class 2 (well) and those interpreted as ill/fatigued. Analysis of between-class differences for the fatigue groups revealed significant differences for all disability and fatigue variables, but with equivalent levels of reported activity and reduction in motivation. Cross-classification against established CDC criteria demonstrated that 89% of subjects constituting Class 2 (well) were indeed nonfatigued controls. A general tendency for grouping CFS cases in the multiple symptomatic classes was noted.

CONCLUSION: This study established reasonably good validity for an empirically-derived latent class solution reflecting considerable heterogeneity among subjects with medically unexplained chronic fatigue. This work strengthens the growing understanding of CFS as a heterogeneous entity comprised of several conditions with different underlying pathophysiological mechanisms.

 

Source: Aslakson E, Vollmer-Conna U, White PD. The validity of an empirical delineation of heterogeneity in chronic unexplained fatigue. Pharmacogenomics. 2006 Apr;7(3):365-73. https://www.ncbi.nlm.nih.gov/pubmed/16610947