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AHRQ Evidence reports and summaries AHRQ Evidence Reports, Numbers 61 - 119 66. Systematic Review of the Current Literature Related to Disability and Chronic Fatigue Syndrome Evidence Report/Technology Assessment Number 66 Prepared for: Contract No. 290-97-0016 Prepared by: AHRQ Publication No. 03-E007 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. This document is in the public domain and may be used and reprinted without permission except those copyrighted materials noted for which further reproduction is prohibited without the specific permission of copyright holders. 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. PrefaceThe Agency for Healthcare Research and Quality (AHRQ), through its Evidence-Based Practice Centers (EPCs), sponsors the development of evidence reports and technology assessments to assist public- and private-sector organizations in their efforts to improve the quality of health care in the United States. The reports and assessments provide organizations with comprehensive, science-based information on common, costly medical conditions and new health care technologies. The EPCs systematically review the relevant scientific literature on topics assigned to them by AHRQ and conduct additional analyses when appropriate prior to developing their reports and assessments. To bring the broadest range of experts into the development of evidence reports and health technology assessments, AHRQ encourages the EPCs to form partnerships and enter into collaborations with other medical and research organizations. The EPCs work with these partner organizations to ensure that the evidence reports and technology assessments they produce will become building blocks for health care quality improvement projects throughout the Nation. The reports undergo peer review prior to their release. AHRQ expects that the EPC evidence reports and technology assessments will inform individual health plans, providers, and purchasers as well as the health care system as a whole by providing important information to help improve health care quality. We welcome written comments on this evidence report. They may be sent to: Director, Center for Practice and Technology Assessment, Agency for Healthcare Research and Quality, 6010 Executive Blvd., Suite 300, Rockville, MD 20852.
The authors are grateful to the following individuals for their diverse contributions throughout the course of this project: Catherine Cella, Janet Connelly, Kyle Fahrbach, Kimberly James, Michael Rozinsky, members of the Technical Expert Panel, peer reviewers, representatives from the Social Security Administration, and representatives from the Agency for Healthcare Research and Quality. Structured AbstractObjective. 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. Conclusions.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. SummaryOverview This purpose of this project, nominated by the Social Security Administration (SSA), and contracted through the Agency for Healthcare Research and Quality (AHRQ) was to develop an evidence base that would provide SSA with the most current medical and scientific knowledge for evaluating disability as defined by the SSA in persons with Chronic Fatigue Syndrome (CFS). This review will also serve to highlight gaps in the current literature and areas ripe for future research. This database of best available evidence was established through a systematic review of the CFS literature pertinent to diagnosis, measurement, and treatment of disability resulting from any medically determinable physical or mental impairment. Reporting the EvidenceSeveral key questions guided this review. Questions were originally posed by SSA and refined in collaboration with expert panel members and representatives from SSA and AHRQ to focus on the issues of disability and impairment in CFS. The revised key questions are as follows:
A multidisciplinary panel of professionals with a broad range of clinical expertise in CFS was assembled early on to provide guidance and direction regarding:
Members of the panel served throughout the course of the project as the Technical Expert Panel (TEP), responding to questions during the review and commenting on the draft evidence report. The systematic review followed a prospective protocol that was developed a priori and shared with the nominating partner (SSA), the TEP, and the Task Order Officer at AHRQ. The protocol outlined the literature search methods, study eligibility criteria, data elements for extraction, and methodological strategies to minimize bias and maximize precision during the process of data collection, extraction, and synthesis. The published literature was searched from January 1, 1988 to November 15, 2001, using Medline, Current Contents, Cochrane Library, and PsychINFO databases. In addition, the bibliographies of all accepted studies and review articles from the past two years were searched for potentially relevant citations. The retrieval cut-off date was March 15, 2002. English language published literature from 1988 to 2001 was sought, utilizing the following search strategy: fatigue syndrome, chronic [MeSH] or chronic fatigue[syndrome].Limits: English language, human subjects. All citations and abstracts were printed and screened at MetaWorks. Full papers were obtained for all abstracts that mentioned CFS and disability. The electronic searches noted above were supplemented by a manual search of the reference lists of all accepted studies and relevant review articles. To be included in the review, studies were required to report CFS as diagnosed according to one of the four accepted CFS definitions, evidence of a medically determinable physical or mental impairment, and data regarding employment or work in at least two adult patients. Data from each accepted study was extracted by one investigator and reviewed by a second. Key data elements sought for extraction from each study included study, patient, and intervention characteristics, as well as outcomes of interest. All eligible papers were evaluated and scored for both internal and external validity, with possible scores ranging from 2 to 8. No quantitative analyses were performed beyond descriptive statistics to summarize findings. Eleven peer reviewers, drawn from clinicians with expertise in CFS and professional organizations, along with eight TEP members reviewed and provided comments on the draft evidence report. Feedback was incorporated into the final report as appropriate. FindingsOf all 3,840 citations identified, 53 studies met all eligibility criteria. The majority of studies were conducted in the United States or Western Europe. There were 17 interventional and 36 observational studies, covering 4,558 primarily female adult patients with CFS. Twenty-two of these studies described comparator groups of healthy controls totaling 775 patients. No quantitative syntheses were possible because of insufficient and/or inconsistent reporting or results. The evidence supports the following conclusions:
It is clear from this review of the literature addressing work status in patients with CFS that more studies are needed to enable researchers to better assess and evaluate disability in this population. Following are priorities for future research:
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