Renee R. Taylor

Chronic Fatigue Syndrome: The Need for Subtypes

Chronic fatigue syndrome (CFS) is an important condition confronting patients, clinicians, and researchers. This article provides information concerning the need for appropriate diagnosis of CFS subtypes. We first review findings suggesting that CFS is best conceptualized as a separate diagnostic entity rather than as part of a unitary model of functional somatic distress. Next, research involving the case definitions of CFS is reviewed. Findings suggest that whether a broad or more conservative case definition is employed, and whether clinic or community samples are recruited, these decisions will have a major influence in the types of patients selected. Review of further findings suggests that subtyping individuals with CFS on sociodemographic, functional disability, viral, immune, neuroendocrine, neurology, autonomic, and genetic biomarkers can provide clarification for researchers and clinicians who encounter CFS’ characteristically confusing heterogeneous symptom profiles. Treatment studies that incorporate subtypes might be particularly helpful in better understanding the pathophysiology of CFS. This review suggests that there is a need for greater diagnostic clarity, and this might be accomplished by subgroups that integrate multiple variables including those in cognitive, emotional, and biological domains.

Fatigue rating scales: an empirical comparison

BACKGROUND There has been limited research comparing the efficacy of different fatigue rating scales for use with individuals with chronic fatigue syndrome (CFS). This investigation explored relationships between two commonly-used fatigue rating scales in CFS research, the Fatigue Scale and the Fatigue Severity Scale. Theoretically, these scales have been described as measuring different aspects of the fatigue construct. The Fatigue Scale was developed as a measure of the severity of specific fatigue-related symptoms, while the Fatigue Severity Scale was designed to assess functional outcomes related to fatigue. METHODS Associations of these scales with the eight definitional symptoms of CFS and with eight domains of functional disability were examined separately in: (1) an overall sample of individuals with a wide range of fatigue severity and symptomatology; (2) a subsample of individuals with CFS-like symptomatology, and, (3) a subsample of healthy controls. RESULTS Findings revealed that both scales are appropriate and useful measures of fatigue-related symptomatology and disability within a general population of individuals with varying levels of fatigue. However, the Fatigue Severity Scale appears to represent a more accurate and comprehensive measure of fatigue-related severity, symptomatology, and functional disability for individuals with CFS-like symptomatology.

Chronic fatigue syndrome, fibromyalgia, and multiple chemical sensitivities in a community-based sample of persons with chronic fatigue syndrome-like symptoms

Objective The aim of this study was to determine illness comorbidity rates for individuals with chronic fatigue syndrome (CFS), fibromyalgia (FM), and multiple chemical sensitivities (MCS). An additional objective was to identify characteristics related to the severity of fatigue, disability, and psychiatric comorbidity in each of these illness groups. Methods A random sample of 18,675 residents in Chicago, Illinois, was first interviewed by telephone. A control group and a group of individuals with chronic fatigue accompanied by at least four minor symptoms associated with CFS received medical and psychiatric examinations. Results Of the 32 individuals with CFS, 40.6% met criteria for MCS and 15.6% met criteria for FM. Individuals with MCS or more than one diagnosis reported more physical fatigue than those with no diagnosis. Individuals with more than one diagnosis also reported greater mental fatigue and were less likely to be working than those with no diagnosis. Individuals with CFS, MCS, FM, or more than one diagnosis reported greater disability than those with no diagnosis. Conclusions Rates of coexisting disorders were lower than those reported in prior studies. Discrepancies may be in part attributable to differences in sampling procedures. People with CFS, MCS, or FM endure significant disability in terms of physical, occupational, and social functioning, and those with more than one of these diagnoses also report greater severity of physical and mental fatigue. The findings illustrate differences among the illness groups in the range of functional impairment experienced.

Estimating rates of chronic fatigue syndrome from a community-based sample: a pilot study.

Most of the Chronic Fatigue Syndrome (CFS) epidemiological studies have relied on physicians who refer patients having at least 6 months of chronic fatigue and other symptoms. However, there are a number of potential problems when using this method to derive prevalence statistics. For example, some individuals with CFS might not have the economic resources to access medical care. Other individuals with CFS might be reluctant to use medical personnel, particularly if they have encountered physicians skeptical of the authenticity of their illness. In addition, physicians that are skeptical of the existence of CFS might not identify cases. In the present pilot study, a random community sample (N=1,031) was interviewed by telephone in order to identify and comprehensively evaluate individuals with symptoms of CFS and those who self-report having CFS. Different definitions of CFS were employed, and higher rates (0.2%) of CFS were found than in previous studies. Methodological benefits in using more rigorous epidemiological methods when estimating CFS prevalence rates are discussed.

Chronic Fatigue Syndrome After Infectious Mononucleosis in Adolescents

OBJECTIVE: The goal was to characterize prospectively the course and outcome of chronic fatigue syndrome in adolescents during a 2-year period after infectious mononucleosis. METHODS: A total of 301 adolescents (12–18 years of age) with infectious mononucleosis were identified and screened for nonrecovery 6 months after infectious mononucleosis by using a telephone screening interview. Nonrecovered adolescents underwent a medical evaluation, with follow-up screening 12 and 24 months after infectious mononucleosis. After blind review, final diagnoses of chronic fatigue syndrome at 6, 12, and 24 months were made by using established pediatric criteria. RESULTS: Six, 12, and 24 months after infectious mononucleosis, 13%, 7%, and 4% of adolescents, respectively, met the criteria for chronic fatigue syndrome. Most individuals recovered with time; only 2 adolescents with chronic fatigue syndrome at 24 months seemed to have recovered or had an explanation for chronic fatigue at 12 months but then were reclassified as having chronic fatigue syndrome at 24 months. All 13 adolescents with chronic fatigue syndrome 24 months after infectious mononucleosis were female and, on average, they reported greater fatigue severity at 12 months. Reported use of steroid therapy during the acute phase of infectious mononucleosis did not increase the risk of developing chronic fatigue syndrome. CONCLUSIONS: Infectious mononucleosis may be a risk factor for chronic fatigue syndrome in adolescents. Female gender and greater fatigue severity, but not reported steroid use during the acute illness, were associated with the development of chronic fatigue syndrome in adolescents. Additional research is needed to determine other predictors of persistent fatigue after infectious mononucleosis.

Comparing the DIS with the SCID: Chronic fatigue syndrome and psychiatric comorbidity

Abstract This study investigated whether psychiatric comorbidity rates in individuals with Chronic Fatigue Syndrome (CFS) change as a function of the type and scoring of psychiatric interview instruments used. The number of DSM-III-R, Axis I psychiatric diagnoses were assessed two times for each of the 18 participants with CFS, once using the Diagnostic Interview Schedule (DIS) and once using the Structured Clinical Interview for the DSM-III-R (SCID). Participants received a significantly greater number of current and total lifetime psychiatric diagnoses resulting from the DIS interview, as opposed to the SCID interview. Fifty percent of participants received at least one current psychiatric diagnosis on the DIS, whereas only 22% received a current psychiatric diagnosis on the SCID. Findings suggested that psychiatric comorbidity rates in individuals with CFS are influenced by the type of psychiatric instrument used. These results help explain the large discrepancies in findings for psychiatric illness in...

Identifying illness parameters in fatiguing syndromes using classical projection methods

OBJECTIVES To examine the potential of multivariate projection methods in identifying common patterns of change in clinical and gene expression data that capture the illness state of subjects with unexplained fatigue and nonfatigued control participants. METHODS Data for 111 female subjects was examined. A total of 59 indicators, including multidimensional fatigue inventory (MFI), medical outcome Short Form 36 (SF-36), Centers for Disease Control and Prevention (CDC) symptom inventory and cognitive response described illness. Partial least squares (PLS) was used to construct two feature spaces: one describing the symptom space from gene expression in peripheral blood mononuclear cells (PBMC) and one based on 117 clinical variables. Multiplicative scatter correction followed by quantile normalization was applied for trend removal and range adjustment of microarray data. Microarray quality was assessed using mean Pearson correlation between samples. Benjamini-Hochberg multiple testing criteria served to identify significantly expressed probes. RESULTS A single common trend in 59 symptom constructs isolates of nonfatigued subjects from the overall group. This segregation is supported by two co-regulation patterns representing 10% of the overall microarray variation. Of the 39 principal contributors, the 17 probes annotated related to basic cellular processes involved in cell signaling, ion transport and immune system function. The single most influential gene was sestrin 1 (SESN1), supporting recent evidence of oxidative stress involvement in chronic fatigue syndrome (CFS). Dominant variables in the clinical feature space described heart rate variability (HRV) during sleep. Potassium and free thyroxine (T4) also figure prominently. CONCLUSION Combining multiple symptom, gene or clinical variables into composite features provides better discrimination of the illness state than even the most influential variable used alone. Although the exact mechanism is unclear, results suggest a common link between oxidative stress, immune system dysfunction and potassium imbalance in CFS patients leading to impaired sympatho-vagal balance strongly reflected in abnormal HRV.

Variability in diagnostic criteria for chronic fatigue syndrome may result in substantial differences in patterns of symptoms and disability.

Chronic fatigue syndrome (CFS) is an illness that involves severe, prolonged exhaustion as well as neurologic, immunologic, and endocrine system pathology. Because the pathogenesis of CFS has yet to be determined, case definitions have relied on clinical observation in classifying signs and symptoms for diagnosis. The current investigation examined differences between CFS as defined by Fukuda and colleagues and a set of criteria that has been stipulated for myalgic encephalomyelitis (ME). Dependent measures included psychiatric comorbidity, symptom frequency, symptom severity, and functional impairment. The ME and Fukuda et al. (1994) CFS criteria were compared with a group having chronic fatigue due to psychiatric reasons. Significant differences occurred primarily with neurologic, neuropsychiatric, fatigue/weakness, and rheumatological symptoms. These findings suggest that it might be inappropriate to synthesize results from studies of this illness that use different definitions to select study populations.

Sexual abuse, physical abuse, chronic fatigue, and chronic fatigue syndrome: a community-based study

Using a randomly selected community-based sample, this investigation examined whether histories of childhood sexual, physical, and death threat abuse predicted adulthood outcomes of specific medical and psychiatric conditions involving chronic fatigue. This study also tested prior suggestions that most individuals with chronic fatigue syndrome report a past history of interpersonal abuse. Multinomial logistic regression was used to examine the relationship between abuse history and chronic fatigue group outcomes while controlling for the effects of sociodemographics. Compared with healthy controls, childhood sexual abuse was significantly more likely to be associated with outcomes of idiopathic chronic fatigue, chronic fatigue explained by a psychiatric condition, and chronic fatigue explained by a medical condition. None of the abuse history types were significant predictors of chronic fatigue syndrome. A closer examination of individuals in the chronic fatigue syndrome group revealed that significantly fewer individuals with CFS reported abuse as compared with those who did not. The implications of these findings are discussed.

Chronic fatigue and sociodemographic characteristics as predictors of psychiatric disorders in a community-based sample.

Objectives To explore the roles of chronic fatigue and sociodemographic characteristics (eg, parental status, work status, socioeconomic status, sex, age, marital status, and ethnicity) as predictors of psychiatric disorders. Methods A stratified random sample of 18,675 adults residing in diverse neighborhoods in Chicago completed a telephone-screening questionnaire. A control group without chronic fatigue (N = 74) and a group of individuals with chronic fatigue (N = 227) were identified and administered a semi-structured psychiatric interview. Stepwise logistic regression analyses predicting occurrence of current and lifetime psychiatric disorders according to chronic fatigue status and sociodemographics were conducted on this overall sample of 301 participants. Results Chronic fatigue, low socioeconomic status, and unemployment were among significant predictors of overall Axis I psychiatric disorders. Chronic fatigue functioned as a predictor for mood and anxiety disorders (including posttraumatic stress disorder), but did not function as a predictor for somatoform disorders, substance abuse/dependence, and eating disorders. Low socioeconomic status and unemployment were significantly associated with current psychiatric disorder, and low socioeconomic status was also significantly associated with mood and anxiety disorders. Women were significantly more likely to experience mood disorder, and minorities (eg, African Americans, Latinos, and individuals of other ethnicity) were significantly more likely to report posttraumatic stress disorder. Conclusions Results support prior findings for increased rates of psychiatric disorder among individuals with chronic fatigue and highlight the roles of low socioeconomic status, unemployment, being a woman, and being classified as a minority in their association with certain psychiatric disorders.