Issues and problems in the conduct of epidemiologic research on chronic fatigue syndrome

Abstract:

The epidemiologic research approach is perhaps most appropriate for initial studies of chronic fatigue syndrome since the syndrome is vaguely defined, scientific knowledge about it is limited, and an infectious etiology is suspected.

Several priority needs appropriate for epidemiologic research are identified, including a refinement of diagnostic criteria; a greater understanding of the natural history of the syndrome; basic incidence, prevalence, and mortality statistics; information on whether asymptomatic cases exist; etiologic studies of possible heterogeneity of cases; investigations of clusters of cases; and determinations of whether patients with the syndrome have an increased risk of malignancy.

Because of the lack of cogent etiologic hypotheses regarding the syndrome, case-control studies are identified as a high priority for research. The many difficulties encountered in conducting such research are discussed and approaches to dealing with these problems are suggested.

 

Source: Grufferman S. Issues and problems in the conduct of epidemiologic research on chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S60-7. http://www.ncbi.nlm.nih.gov/pubmed/2020803

 

Defining the chronic fatigue syndrome

Abstract:

The recently published working definition of the chronic fatigue syndrome (CFS) is a necessary first step toward a consistent effort to research this controversial illness. Before this definition was developed, cases often were defined vaguely, according to the perceptions and biases of the individual researchers, so that the results of some studies were unclear. However, few specific diagnostic parameters for CFS exist, and the new definition may not delineate a single clinicopathologic entity.

Future efforts at researching this illness should be aimed at identifying parameters that differentiate CFS from psychiatric conditions such as major depression and from other defined chronic diseases. Because CFS may be the result of multiple disease processes, the separate study of well-defined subgroups of patients with CFS is appropriate.

Such subgroups of patients are probably more likely to have common pathogenetic features than are patients with CFS as a whole group.

 

Source: Holmes GP. Defining the chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S53-5. http://www.ncbi.nlm.nih.gov/pubmed/2020802

 

Risk factors associated with chronic fatigue syndrome in a cluster of pediatric cases

Abstract:

After seven pediatric cases of chronic fatigue syndrome (CFS) were diagnosed in a farming community in upstate New York, a questionnaire regarding symptoms and potential risk factors of CFS was distributed to all students enrolled in the same school district.

Twenty-one students with symptoms of CFS were identified. Two controls per case matched for age and sex were randomly selected from questionnaire respondents. Health status was verified for all subjects by telephone, and diagnosis of CFS was confirmed by a physician.

Information was collected on the following factors: symptoms of CFS among other family members; history of allergy/asthma; consumption of raw milk, raw eggs, raw cheese, or raw meat; water supply; exposure to animals; home heating source; proximity to farmland/orchards; tick bite; blood transfusion; camping; and appendicitis.

Logistic-regression analyses indicated that the best model (characterized by symptoms among other family members, recent ingestion of raw milk, and history of allergy/asthma) produced significant estimates of relative risk (P less than .05) of 35.9, 44.3, and 23.3, respectively, for the three factors (corrections were made for the effect of the other covariates).

These data suggest that a combination of host and environmental factors, including an infectious agent or agents, are involved in the etiology of CFS.

 

Source: Bell KM, Cookfair D, Bell DS, Reese P, Cooper L. Risk factors associated with chronic fatigue syndrome in a cluster of pediatric cases. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S32-8. http://www.ncbi.nlm.nih.gov/pubmed/2020801

 

Medical aspects of delayed convalescence

Abstract:

Disease and illness are not synonymous. In most instances, disease is demonstrable by anatomic, physiologic, biochemical, microbiologic, or immunologic abnormalities. Disease is a pathologic process. Not all persons with a disease are sick or ill. Symptoms of illness associated with a disease may be manifest or persist after the disease has disappeared.

The absence of demonstrable disease, however, does not necessarily mean that symptoms of illness are unreal. Recovery from disease and recovery from illness are not always equated. Many factors, including personal characteristics and social circumstances, can be responsible for recovery from disease and illness.

Chronic fatigue syndrome or symptoms of illness can persist in some patients but not in others after many different diseases.

 

Source: Cluff LE. Medical aspects of delayed convalescence. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S138-40.  http://www.ncbi.nlm.nih.gov/pubmed/2020799

 

Nervous system-immune system communication

Abstract:

This essay is based on the premise that certain individuals may have a biologically determined propensity to respond to infection that is manifested by the development of disease such as chronic fatigue syndrome; the sequence of events that leads to this response involves the immune system. Biochemical pathways between the immune and nervous systems are reviewed, and the role of various products in the systemic circulation, including interleukin-1, pituitary hormone, and catecholamines, is highlighted. This premise could be tested by measuring levels of these substances in carefully selected patients and controls.

 

Source: Arnason BG. Nervous system-immune system communication. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S134-7. http://www.ncbi.nlm.nih.gov/pubmed/2020798

 

Assessment of depression in patients with chronic fatigue syndrome

Abstract:

Assessment of the relationship of depression to chronic fatigue syndrome (CFS) is a complicated but important topic. This relationship may range from the misdiagnostic (i.e., depression misidentified as CFS) to the etiologic (i.e., CFS causes an organic affective syndrome). Assessment should focus on the symptoms and syndromes of depressive disorder, utilization of a single rating scale to assess presumed depression is discouraged, and alternate approaches to classification that allow for symptomatic overlap of a major depressive disorder and CFS are suggested. Careful attention needs to be given to the use of external validating criteria in empiric studies, such as natural history, clinical course (including treatment response), and family history.

 

Source:  Thase ME. Assessment of depression in patients with chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S114-8. http://www.ncbi.nlm.nih.gov/pubmed/2020797

 

Testing of vestibular function: an adjunct in the assessment of chronic fatigue syndrome

Abstract:

Patients with chronic fatigue syndrome (CFS) often complain of dysequilibrium that is nonspecific. The basis of this complaint is unknown but may be related to vestibular system abnormalities, in that an association between inner-ear deficits and infectious mononucleosis has been established in the medical literature. An overview of quantitative vestibular function testing is given, including vestibulo-ocular and vestibulospinal tests. The basic principles of caloric and rotational testing are provided, including the interaction between vision and the vestibular system. Moving-platform posturography is described. Preliminary results from quantitative vestibular function testing of a small group of individuals with CFS are provided.

 

Source:  Furman JM. Testing of vestibular function: an adjunct in the assessment of chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S109-11. http://www.ncbi.nlm.nih.gov/pubmed/2020795

 

Mania and recovery from chronic fatigue syndrome

A syndrome of disabling fatigue variously labelled myalgic encephalomyelitis (ME), post-viral fatigue, or chronic fatigue syndrome (CFS)1 has received much recent attention(2,3). Depression occurs in up to half of hospital referrals with CFS4-f and in these cases, may explain the symptoms  (7). However, despite suggestions of muscular dysfunction(8) the cause in the remainder is unknown. The following case is reported with reference to this question.

You can read the rest of this article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293060/pdf/jrsocmed00128-0067.pdf

 

Source: M C Sharpe, B A Johnson, and J McCann. Mania and recovery from chronic fatigue syndrome. J R Soc Med. 1991 Jan; 84(1): 51–52. PMCID: PMC1293060 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293060/

 

Review of laboratory findings for patients with chronic fatigue syndrome

Abstract:

Various abnormalities revealed by laboratory studies have been reported in adults with chronic fatigue syndrome. Those most consistently reported include depressed natural killer cell function and reduced numbers of natural killer cells; low levels of circulating immune complexes; low levels of several autoantibodies, particularly antinuclear antibodies and antithyroid antibodies; altered levels of immunoglobulins; abnormalities in number and function of lymphocytes; and modestly elevated levels of two Epstein-Barr virus-related antibodies, immunoglobulin G to viral capsid antigen and to early antigen.

 

Source: Buchwald D, Komaroff AL. Review of laboratory findings for patients with chronic fatigue syndrome. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S12-8. http://www.ncbi.nlm.nih.gov/pubmed/1902321

 

Chronic fatigue syndrome: thoughts on pathogenesis

Abstract:

Studies have shown that a proportion of patients with severe chronic infection due to Epstein-Barr virus (EBV) lack antibody to a component of EBV nuclear antigen. However, it is not clear whether this circumstance is one of cause or effect in regard to the pathogenesis of chronic fatigue syndrome (CFS); it is clearly not pathognomonic since it also occurs in persons infected with the human immunodeficiency virus and–rarely–in those with other EBV-related conditions. Stress and depression may be other pathogenetic mechanisms that could reactivate EBV and lead to CFS; examples of this phenomenon are given. The syndrome might also follow certain other viral infections as part of a process that has been called postinfectious neurasthenia. Currently, the cause(s) and cure of CFS, a common and distressing syndrome, are enigmatic and require multidisciplinary study.

 

Source: Evans AS. Chronic fatigue syndrome: thoughts on pathogenesis. Rev Infect Dis. 1991 Jan-Feb;13 Suppl 1:S56-9. http://www.ncbi.nlm.nih.gov/pubmed/1850544