Category: Case Definition

Idiopathic chronic fatigue and chronic fatigue syndrome: a comparison of two case-definitions

Abstract:

The aim of the study was to compare the signs and symptoms of individuals meeting two different definitions of chronic fatigue syndrome (CFS). Ninety-four patients fitting the eligibility criteria for idiopathic fatigue were enrolled into the study. Of the 94 patients, 48 met the 1988 definition of CFS, 20 the 1994 (but not the 1988) definition of CFS, and 26 met neither definition.

The 1994 defined cases were more likely than 1988 defined cases, and non-syndromal individuals to be male, married, and high school educated. The 1994 cases were less likely than 1988 cases to present acute onset, self reported sore throat, mild fever lymphadenopathy, pharyngitis.

In conclusion, the 1994 criteria increased the number of patients classified as CFS; however, those who fit only the 1994 criteria were less likely to have an acute symptomatic onset and signs and symptoms suggestive of an infectious process.

 

Source: Arpino C, Carrieri MP, Valesini G, Pizzigallo E, Rovere P, Tirelli U, Conti F, Dialmi P, Barberio A, Rusconi N, Bosco O, Lazzarin A, Saracco A, Moro ML,Vlahov D. Idiopathic chronic fatigue and chronic fatigue syndrome: a comparison of two case-definitions. Ann Ist Super Sanita. 1999;35(3):435-41. http://www.ncbi.nlm.nih.gov/pubmed/10721210

 

Developing case definitions for symptom-based conditions: the problem of specificity

Symptom-based conditions are postulated organic diseases that are characterized primarily by chronic physical (somatic) symptoms (1, 2). Contemporary conditions associated with multisystem complaints are generally referred to as chronic fatigue syndrome, fibromyalgia, multiple chemical sensitivities, silicone associated atypical rheumatic disease, sick building syndrome, and most recently, Gulf War syndrome (table 1). Possibly related disorders that will not be considered in the following analysis include epidemic neuromyasthenia, hyperventilation syndrome, reactive hypoglycemia, post-lyme disease syndrome, and irritable bowel syndrome (3).

Although the need to consistently define symptombased conditions has been repeatedly emphasized, there has been limited progress in establishing widely accepted diagnostic criteria (1,4). Based on reports in English-language publications, symptom-based conditions were analyzed to determine why it has been difficult to develop case definitions of unique diseases.

You can read the rest of this article here: http://epirev.oxfordjournals.org/content/20/2/148.long

 

Source: Hyams KC. Developing case definitions for symptom-based conditions: the problem of specificity. Epidemiol Rev. 1998;20(2):148-56. http://epirev.oxfordjournals.org/content/20/2/148.long (Full article)

Chronic fatigue and chronic fatigue syndrome: shifting boundaries and attributions

Abstract:

The subjective symptom of “fatigue” is one of the most widespread in the general population and is a major source of healthcare utilization. Prolonged fatigue is often associated with neuropsychological and musculoskeletal symptoms that form the basis of several syndromal diagnoses including chronic fatigue syndrome, fibromyalgia, and neurasthenia, and is clearly not simply the result of a lack of force generation from the muscle.

Current epidemiologic research in this area relies predominantly on self-report data to document the prevalence and associations of chronic fatigue. Of necessity, this subjective data source gives rise to uncertain diagnostic boundaries and consequent divergent epidemiologic, clinical, and pathophysiologic research findings.

This review will highlight the impact of the case definition and ascertainment methods on the varying prevalence estimates of chronic fatigue syndrome and patterns of reported psychological comorbidty. It will also evaluate the evidence for a true postinfective fatigue syndrome.

 

Source: Lloyd AR. Chronic fatigue and chronic fatigue syndrome: shifting boundaries and attributions. Am J Med. 1998 Sep 28;105(3A):7S-10S. http://www.ncbi.nlm.nih.gov/pubmed/9790475

 

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