Category: Case Definition

Factor analysis of unexplained severe fatigue and interrelated symptoms: overlap with criteria for chronic fatigue syndrome

Abstract:

The objective of this study was to identify factors explaining the correlations among unexplained severe fatigue of different durations (1-5 months or > or =6 months) and symptoms reported as being significant health problems during a preceding 4-week period.

Between June and December of 1994, a cross-sectional, random digit dialing telephone survey was conducted among residents of San Francisco, California. All subjects who reported having severe fatigue lasting for > or =1 month and a random sample of nonfatigued subjects were asked to participate in a detailed telephone interview. Data from 1,510 individuals aged 18-60 years who did not have medical or psychiatric conditions that could explain their severe fatigue were analyzed.

Common factor analyses identified three correlated factors (defined as “fatigue-mood-cognition” symptoms, “flu-type” symptoms, and “visual impairment”) that explained the correlations among fatigue lasting for > or =6 months and 14 interrelated symptoms. No factor explained the correlations among fatigue lasting for 1-5 months and other symptoms.

The combination of fatigue of > or =6 months’ duration and selected symptoms overlaps with published criteria used to define cases of chronic fatigue syndrome (CFS). Although symptoms described in this study were reported as appearing within the preceding month, and CFS symptoms must have been present for the previous 6 months, these results provide empirical support for the interrelations among unexplained fatigue of > or =6 months’ duration and symptoms included in the CFS case definition.

 

Source: Nisenbaum R, Reyes M, Mawle AC, Reeves WC. Factor analysis of unexplained severe fatigue and interrelated symptoms: overlap with criteria for chronic fatigue syndrome. Am J Epidemiol. 1998 Jul 1;148(1):72-7. http://aje.oxfordjournals.org/content/148/1/72.long (Full article)

 

Politics, science, and the emergence of a new disease. The case of chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) emerged as a diagnostic category during the last decade. Initial research suggested that CFS was a relatively rare disorder with a high level of psychiatric comorbidity. Many physicians minimized the seriousness of this disorder and also interpreted the syndrome as being equivalent to a psychiatric disorder. These attitudes had negative consequences for the treatment of CFS.

By the mid-1990s, findings from more representative epidemiological studies indicated considerably higher CFS prevalence rates. However, the use of the revised CFS case definition might have produced heterogeneous patient groups, possibly including some patients with pure psychiatric disorders.

Social scientists have the expertise to more precisely define this syndrome and to develop appropriate and sensitive research strategies for understanding this disease.

Comment in: The biopsychosocial model and chronic fatigue syndrome. [Am Psychol. 1998]

 

Source: Jason LA, Richman JA, Friedberg F, Wagner L, Taylor R, Jordan KM. Politics, science, and the emergence of a new disease. The case of chronic fatigue syndrome. Am Psychol. 1997 Sep;52(9):973-83. http://www.ncbi.nlm.nih.gov/pubmed/9301342

 

Definition of “chronic fatigue syndrome” (CFS)

Abstract:

The definition of “Chronic Fatigue Syndrome” (CFS) in 1988 was an attempt to establish a uniform basis for the previously heterogeneous approaches to research of this severe and inexplicable state of fatigue. At the same time, researchers wished to narrow down a pathogenetically founded disease entity a priori by specifying precise disease criteria.

The empirical data gathered in accordance with the CFS definition, however, have failed to confirm the assumption that the disease entity is pathogenetically uniform. Furthermore, the originally selected criteria have proven to be impracticable ore theoretically questionable. In the period that followed, modifications that permitted a more comprehensive and yet more differentiated classification of fatigue states of unclear etiology were proposed.

The new research approach avoids postulation of causal entities and puts CFS back in a category with other descriptive states of fatigue.

 

Source: Heyll U, Wachauf P, Senger V, Diewitz M. Definition of “chronic fatigue syndrome” (CFS). Med Klin (Munich). 1997 Apr 15;92(4):221-7. [Article in German] http://www.ncbi.nlm.nih.gov/pubmed/9221305

 

The rise and fall of the chronic fatigue syndrome as defined by Holmes et al.

Abstract:

This paper is a sequel to my monograph on neurocirculatory asthenia and chronic fatigue syndrome. It pays special attention to the nature of chronic fatigue syndrome, to the forms of neurocirculatory asthenia, and above all to the 6th form in which profound fatigue is the dominant symptom. All forms including the 6th are characterized by the presence of concomitant symptoms due to dysfunction of the autonomic nervous system. Chronic fatigue syndrome as defined by Holmes et al is devoid of these symptoms. Up till the present day no case histories of it have been published. It is argued that chronic fatigue syndrome sensu Holmes et al does not exist, the 6th form of neurocirculatory asthenia having to take up its place.

 

Source: van Waveren EK. The rise and fall of the chronic fatigue syndrome as defined by Holmes et al. Med Hypotheses. 1996 Feb;46(2):63-6. http://www.ncbi.nlm.nih.gov/pubmed/8692045

 

A comparison of the characteristics of chronic fatigue syndrome in primary and tertiary care

Abstract:

BACKGROUND: To evaluated the characteristics of Chronic Fatigue Syndrome (CFS) in primary and tertiary care.

METHOD: A comparison of subjects fulfilling criteria for CFS, identified as part of a prospective cohort study in primary care, compared to 79 adults fulfilling the same criteria referred for treatment to a specialist CFS clinic.

RESULTS: Hospital cases were more likely to belong to upper socio-economic groups, and to have physical illness attributions. They had higher levels of fatigue and more somatic symptoms, and were more impaired functionally, but had less overt psychological morbidity. Women were over-represented in both primary care and hospital groups. Nearly half of those referred to a specialist clinic did not fulfil operational criteria for CFS.

CONCLUSION:The high rates of psychiatric morbidity and female excess that characterise CFS in specialist settings are not due to selection bias. On the other hand higher social class and physical illness attributions may be the result of selection bias and not intrinsic to CFS.

 

Source: Euba R, Chalder T, Deale A, Wessely S. A comparison of the characteristics of chronic fatigue syndrome in primary and tertiary care. Br J Psychiatry. 1996 Jan;168(1):121-6. http://www.ncbi.nlm.nih.gov/pubmed/8770441

 

An examination of the working case definition of chronic fatigue syndrome

Abstract:

PURPOSE: Chronic fatigue syndrome (CFS) currently is defined by a working case definition developed under the leadership of the United States Centers for Disease Control and Prevention (CDC) based on a consensus among experienced clinicians. We analyzed the experience from one large center to examine the adequacy of the case definition.

PATIENTS AND METHODS: Predefined clinical and laboratory data were collected prospectively from 369 patients with debilitating fatigue, of whom 281 (76%) met the major criteria of the original CDC case definition for CFS: (1) fatigue of at least 6 months’ duration, seriously interfering with the patient’s life; and (2) without evidence of various organic or psychiatric illnesses that can produce chronic fatigue. The same clinical data were obtained from 311 healthy control subjects and two comparison groups with diseases that can present in a similar fashion; relapsing-remitting multiple sclerosis (n = 25) and major depression (n = 19).

RESULTS: All of the minor criteria symptoms from the original CDC case definition distinguished patients with debilitating chronic fatigue from healthy control subjects, and many distinguished the patients with chronic fatigue from the comparison groups with multiple sclerosis and depression: myalgias, postexertional malaise, headaches, and a group of infectious-type symptoms (ie, chronic fever and chills, sore throat, swollen glands in the neck or underarm areas). In addition, two other symptoms not currently part of the case definition discriminated the chronic fatigue patients from the control/comparison groups: anorexia and nausea. Physical examination criteria only infrequently contributed to the diagnosis. Patients meeting the CDC major criteria for CFS also met the minor criteria in 91% of cases.

CONCLUSION: Patients meeting the major criteria of the current CDC working case definition of CFS reported symptoms that were clearly distinguishable from the experience of healthy control subjects and from disease comparison groups with multiple sclerosis and depression. Eliminating three symptoms (ie, muscle weakness, arthralgias, and sleep disturbance) and adding two others (ie, anorexia and nausea) would appear to strengthen the CDC case definition of CFS.

 

Source: Komaroff AL, Fagioli LR, Geiger AM, Doolittle TH, Lee J, Kornish RJ, Gleit MA, Guerriero RT. An examination of the working case definition of chronic fatigue syndrome. Am J Med. 1996 Jan;100(1):56-64. http://www.ncbi.nlm.nih.gov/pubmed/8579088

 

Can the chronic fatigue syndrome be defined by distinct clinical features?

Abstract:

To determine whether patients diagnosed as having chronic fatigue syndrome (CFS) constitute a clinically homogeneous class, multivariate statistical analyses were used to derive symptom patterns and potential patient subclasses in 565 patients. The notion that patients currently diagnosed as having CFS constitute a single homogeneous class was rejected.

An alternative set of clinical subgroups was derived. The validity of these subgroups was assessed by sociodemographic, psychiatric, immunological and illness behaviour variables. A two-class statistical solution was considered most coherent, with patients from the smaller class (27% of the sample) having clinical characteristics suggestive of somatoform disorders. The larger class (73% of sample) presented a more limited combination of fatigue and neuropsychological symptoms, and only moderate disability but remained heterogeneous clinically. The two patient groups differed with regard to duration of illness, spontaneous recovery, severity of current psychological morbidity, utilization of medical services and CD8 T cell subset counts. The distribution of symptoms among patients was not unimodal, supporting the notion that differences between the proposed subclasses were not due simply to differences in symptom severity.

This study demonstrated clinical heterogeneity among patients currently diagnosed as CFS, suggesting aetiological heterogeneity. In the absence of discriminative clinical features, current consensus criteria do not necessarily reduce the heterogeneity of patients recruited to CFS research studies.

 

Source: Hickie I, Lloyd A, Hadzi-Pavlovic D, Parker G, Bird K, Wakefield D. Can the chronic fatigue syndrome be defined by distinct clinical features? Psychol Med. 1995 Sep;25(5):925-35. http://www.ncbi.nlm.nih.gov/pubmed/8588011

 

Chronic fatigue syndrome: a clinical and laboratory study with a well matched control group

Abstract:

OBJECTIVE: To investigate the relation between severity of complaints, laboratory data and psychological parameters in patients with chronic fatigue syndrome (CFS).

SUBJECTS: Eighty-eight patients with CFS and 77 healthy controls matched for age, sex and geographical area.

METHODS: Patients and controls visited our outpatient clinic for a detailed medical history, physical examination and psychological tests: Checklist Individual Strength (CIS). Beck Depression Inventory (BDI) and Sickness Impact Profile (SIP). Venous blood was drawn for a complete blood cell count, serum chemistry panel, C-reactive protein and serological tests on a panel of infectious agents.

RESULTS: All patients fulfilled the criteria for CFS as described by Sharpe et al. (J R Soc Med 1991; 84: 118-21), only 18 patients (20.5%) fulfilled the CDC criteria. The outcome of serum chemistry tests and haematological tests were within the normal range. No significant differences were found in the outcome of serological tests. Compared to controls, significant differences were found in the results on the CIS, the BDI, and the SIP. These results varied with the number of complaints (CDC criteria). When the number of complaints was included as the covariate in the analysis, there were no significant differences on fatigue severity, depression, and functional impairment between patients who fulfilled the CDC criteria and patients who did not.

CONCLUSION: It is concluded that the psychological parameters of fatigue severity, depression and functional impairment are related to the clinical severity of the illness. Because the extensive panel of laboratory tests applied in this study did not discriminate between patients and controls, it was not possible to investigate a possible relation between the outcomes of psychological and laboratory testing.

Comment in: Chronic fatigue syndrome: a clinical and laboratory study with a well-matched control group. [J Intern Med. 2004]

 

Source: Swanink CM, Vercoulen JH, Bleijenberg G, Fennis JF, Galama JM, van der Meer JW. Chronic fatigue syndrome: a clinical and laboratory study with a well matched control group. J Intern Med. 1995 May;237(5):499-506. http://www.ncbi.nlm.nih.gov/pubmed/7738491

 

Chronic fatigue syndrome and myalgic encephalomyelitis

Comment on:

Chronic fatigue syndrome. Distinguish between syndromes… [BMJ. 1994]

Chronic fatigue syndrome. Role of psychological factors overemphasised. [BMJ. 1994]

 

Editor,-Our recent editorial on the chronic fatigue syndrome and myalgic encephalomyelitis prompted considerable correspondence,’ which raised issues of case definition, clinical management, and attitudes towards people with psychiatric illnesses. Sadly, many of our critics show that the editor of the BMJ is wrong to state in the “editor’s choice” in the issue of 14 May that “only the naivest medical students think that diseases have some independent, objective reality.” Medical students show greater intellectual sophistication in tackling the classification of ill defined illnesses than many patients and doctors-and particularly medical practitioners with self diagnosed myalgic encephalomyelitis.

Case definition-Ellen M Goudsmit’ and Nick Anderson’ assert that research criteria for the chronic fatigue syndrome fail to distinguish myalgic encephalomyelitis and exaggerate psychiatric associations. The best replicated research finding, however, is that patients suffer substantial emotional morbidity, whether the chronic fatigue syndrome is defined by British or, as patient groups prefer, Australian or American criteria. All three sets of criteria can be used to identify cases on a continuum of fatigue, which includes myalgic encephalomyelitis. We did not cite DO Ho-Yen’s prevalence study as it used an idiosyncratic definition of cases of the ‘chronic fatigue syndrome and surveyed doctors’ diagnoses rather than patients.

You can read the full comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540769/pdf/bmj00450-0067b.pdf

 

Source: Lawrie SM, Pelosi AJ. Chronic fatigue syndrome and myalgic encephalomyelitis. BMJ. 1994 Jul 23;309(6949):275. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2540769/

 

Chronic fatigue syndrome: point and counterpoint

Abstract:

Two clinical investigators with divergent views on chronic fatigue syndrome (CFS) were invited to debate their positions at the 1993 annual meeting of The Infectious Disease Society of America. Major points of the discourse focused on the value of the US Centers for Disease Control and Prevention case definition of CFS, the potential roles of infectious and allergic problems in the syndrome, the confounding problem of concurrent psychiatric problems, and the utility of diagnostic tests.

 

Source: Straus SE, Komaroff AL, Wedner HJ. Chronic fatigue syndrome: point and counterpoint. J Infect Dis. 1994 Jul;170(1):1-6. http://www.ncbi.nlm.nih.gov/pubmed/8014482