Identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution

Abstract:

BACKGROUND: A recent article by Reeves et al. on the identification and resolution of ambiguities in the 1994 chronic fatigue syndrome (CFS) research case definition recommended the Checklist Individual Strength, the Chalder Fatigue Scale, and the Krupp Fatigue Severity Scale for evaluating fatigue in CFS studies. To be able to discriminate between various levels of severe fatigue, extreme scoring on the individual items of these questionnaires must not occur too often.

METHODS: We derived an expression that allows us to compute a lower bound for the number of items with the maximum item score for a given study from the reported mean scale score, the number of reported subjects, and the properties of the fatigue rating scale. Several CFS studies that used the recommended fatigue rating scales were selected from literature and analyzed to verify whether abundant extreme scoring had occurred.

RESULTS: Extreme scoring occurred on a large number of the items for all three recommended fatigue rating scales across several studies. The percentage of items with the maximum score exceeded 40% in several cases. The amount of extreme scoring for a certain scale varied from one study to another, which suggests heterogeneity in the selected subjects across studies.

CONCLUSION: Because all three instruments easily reach the extreme ends of their scales on a large number of the individual items, they do not accurately represent the severe fatigue that is characteristic for CFS. This should lead to serious questions about the validity and suitability of the Checklist Individual Strength, the Chalder Fatigue Scale, and the Krupp Fatigue Severity Scale for evaluating fatigue in CFS research.

Comment on: Identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution. [BMC Health Serv Res. 2003]

 

Source: Stouten B. Identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution. BMC Health Serv Res. 2005 May 13;5:37. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1175848/ (Full article)

 

Fatigue in disease-free cancer patients compared with fatigue in patients with chronic fatigue syndrome

Abstract:

The goal of our work was to assess fatigue in disease-free cancer patients with help of a validated fatigue questionnaire. Furthermore, we wished to analyse the relationship between severe fatigue and former treatment modalities, problems of concentration and motivation, physical activity, functional impairment, depression and anxiety and finally, to compare severely fatigued disease-free cancer patients and patients with Chronic Fatigue Syndrome (CFS).

The participants were 85 adult cancer patients and 16 patients with CFS. The cancer patients were all disease-free and had been off treatment for a minimum of 6 months. They were asked to participate in this study by their physician when they came to the hospital for control visits. Patients who were willing to participate completed four questionnaires. The Checklist Individual Strength was used to measure fatigue. In addition, the Beck Depression Inventory, the Spielberger Trait Anxiety Inventory and the Nottingham Health Profile were used.

Results indicate that 19% of the disease-free cancer patients were severely fatigued. Their fatigue experience is comparable to that of patients with CFS. Severe fatigue is associated with problems of concentration and motivation, reduced physical activity, emotional health problems and pain.

Furthermore, a relation was found between fatigue and depression and anxiety. No relation was found between fatigue and type of cancer, former treatment modalities, duration of treatment and time since treatment ended. In conclusion, for one fifth of a group of disease-free cancer patients fatigue is a severe problem long after treatment. In addition to fatigue, these patients experience several psychological and physical problems.

 

Source: Servaes P, van der Werf S, Prins J, Verhagen S, Bleijenberg G. Fatigue in disease-free cancer patients compared with fatigue in patients with chronic fatigue syndrome. Support Care Cancer. 2001 Jan;9(1):11-7. http://www.ncbi.nlm.nih.gov/pubmed/11147137

 

Lymphocyte subsets, apoptosis, and cytokines in patients with chronic fatigue syndrome

Abstract:

Whether immunologic abnormalities correlate with fatigue severity and functional impairment in chronic fatigue syndrome (CFS) was investigated. Blood mononuclear cells were immunophenotyped and circulating ex vivo-produced cytokines were measured in 76 CFS patients and 69 healthy matched controls. Expression of CD11b on CD8 cells was significantly decreased in CFS patients. However, the previously reported increased expression of CD38 and HLA-DR was not confirmed. There was no obvious difference in apoptosis in leukocyte cultures, circulating cytokines, and ex vivo production of interleukin (IL)-1 alpha and IL-1 receptor antagonist. Endotoxin-stimulated ex vivo production of tumor necrosis factor-alpha and IL-beta was significantly lower in CFS. The immunologic test results did not correlate with fatigue severity or psychologic well-being was measured by Checklist Individual Strength, Beck Depression Inventory, and Sickness Impact Profile. Thus, these immunologic tests cannot be used as diagnostic tools in individual CFS patients.

 

Source: Swanink CM, Vercoulen JH, Galama JM, Roos MT, Meyaard L, van der Ven-Jongekrijg J, de Nijs R, Bleijenberg G, Fennis JF, Miedema F, van der Meer JW. Lymphocyte subsets, apoptosis, and cytokines in patients with chronic fatigue syndrome. J Infect Dis. 1996 Feb;173(2):460-3. http://jid.oxfordjournals.org/content/173/2/460.long (Full article)

 

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