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Cover of Systematic Review of the Current Literature Related to Disability and Chronic Fatigue Syndrome

Systematic Review of the Current Literature Related to Disability and Chronic Fatigue Syndrome

Evidence Reports/Technology Assessments, No. 66

Investigators: , MD, Principal Investigator, , MD, , RN, BSN, , MEM, , RN, MS, CPNP, and , BA. , MD, FRCPC, Program Director.

Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 03-E007

Structured Abstract


The objective of this evidence report was to perform a systematic review of the published literature to provide the Social Security Administration (SSA) with the best available evidence and most current medical knowledge regarding disability in persons with Chronic Fatigue Syndrome (CFS).

Search Strategy:

English language and adult population published literature from 1988 to November 2001 was searched using MEDLINE, Current Contents, Cochrane Library, and PsychINFO databases and supplemented by a manual review of bibliographies of all accepted papers.

Selection Criteria:

Interventional or observational studies of at least two adult patients reporting CFS according to either the CDC 1988, CDC 1994, Oxford 1991, or Australia 1990 criteria were accepted. Studies were required to report disability (evidence of a medically determinable physical or mental impairment) and data regarding employment or work.

Data Collection and Analysis:

Data on patients, interventions, and outcomes were extracted from accepted studies. Studies were scored for quality and level of evidence. Data were summarized for study, patient, and treatment level characteristics as well as outcomes of interest. A panel of diverse technical experts and peer reviewers provided review and commentary on the draft report.

Main Results:

Of 3,840 citations identified, 53 studies describing 4,558 patients with CFS met all eligibility criteria. Twenty-two of these studies described comparator groups of healthy controls totaling 775 patients. The majority of CFS patients represented in the 37 studies reporting employment status were unemployed. The evidence suggests that some individuals with CFS have cognitive or affective impairments on neuropsychological tests, but results are not consistent. Depression of greater severity is associated with unemployment, but no other impairment appeared to be consistently associated with disability or work outcomes. No specific interventions have been proven to be effective in restoring the ability to work. No specific patient characteristics have been identified as best predictors of positive employment outcomes in CFS patients. The patient's level of functioning at the time of diagnosis should be compared to functioning prior to the onset of illness especially as it relates to work, school, social and home activities.

The major limitations of this review are related to the weaknesses inherent in the current medical and scientific published literature regarding CFS. Study designs were not sufficiently homogeneous to allow quantitative synthesis of individual study results, and external validity was low. While some studies reported test and scale results, this was highly variable with relatively sparse and inconsistent reporting of both baseline and outcome data. No studies specifically measured the impact of baseline impairment data or treatment interventions on work function or employment outcomes.


While relationships between various impairment measures and work/disability status might be explored in some cases, the best available evidence from the literature did not allow for determination of causality. The limitations inherent in the current literature review are noted and the research community is urged to conduct methodologically rigorous, longitudinal, interventional studies to determine what baseline characteristics are associated with inability to work, and what interventions are effective in restoring the ability to work in the CFS population.


Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services.1 Contract No. 290-97-0016. Prepared by: MetaWorks Inc. Evidence-based Practice Center, Medford, MA.

Suggested citation:

Levine C, Ganz N, Estok R, et al. Systematic Review of the Current Literature Related to Disability and Chronic Fatigue Syndrome. Evidence Report/Technology Assessment No. 66 (Prepared by MetaWorks Inc. Evidence-based Practice Center under Contract No 290-97-0016). AHRQ Publication No. 03-E007. Rockville, MD: Agency for Healthcare Research and Quality. December 2002.

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

AHRQ is the lead Federal agency charged with supporting research designed to improve the quality of health care, reduce its cost, address patient safety and medical errors, and broaden access to essential services. AHRQ sponsors and conducts research that provides evidence-based information on health care outcomes; quality; and cost, use, and access. The information helps health care decisionmakers--patients and clinicians, health system leaders, and policymakers--make more informed decisions and improve the quality of health care services.

The authors of this report are responsible for its content. Statements in the report should not be construed as endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services of a particular drug, device, test, treatment, or other clinical service.


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Bookshelf ID: NBK36735


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