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Systematic review of the current literature related to disability and chronic fatigue syndrome |
Ganz N, Frame D, Estok R, Stone L, Ludensky V |
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Authors' objectives The overall review objective was to assess how best to measure, monitor and treat disability in patients with chronic fatigue syndrome (CFS). This structured abstract focuses on the sub-question in the review: What is the evidence that in individuals with CFS, treatments are effective in restoring the ability to work?
Searching MEDLINE, Current Contents, the Cochrane Library and PsycINFO were searched (January 1988 to November 2001) for relevant studies; the search terms were reported. The studies were restricted to those published in English and conducted in the USA, Canada, Australia or Western Europe.
Study selection Study designs of evaluations included in the reviewRandomised controlled trials (RCTs), non-randomised controlled trials, observational studies (prospective, retrospective and cross-sectional) and uncontrolled case series studies were eligible for inclusion. Reviews, meta-analyses, abstracts, letters, case reports, editorials, commentaries, and studies containing less than 2 patients as the total sample, were excluded.
Specific interventions included in the reviewNo inclusion criteria were specified in relation to the type of interventions. The included studies were of behavioural, psychiatric and physical therapy.
Participants included in the reviewAdults with a diagnosis of CFS and disability according to one of four accepted diagnostic definitions were eligible for inclusion. Studies that included a paediatric population, or studies of mixed populations in which it was not possible to separate the patients with CFS, were excluded.
Outcomes assessed in the reviewStudies that included a medically determinable physical or mental impairment and also reported at least one measure related to disability were eligible for inclusion. The outcomes assessed in the included studies encompassed work-related, cognitive, disease severity, exercise, functional, general health, mental health and physical activity.
How were decisions on the relevance of primary studies made?The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.
Assessment of study quality Study quality was assessed according to three different checklists, depending on the study design. The first checklist, which assessed internal validity, was used to rate all studies. This assessed whether CFS was defined according to acceptable diagnostic criteria; tests for medically determinable physical and/or mental impairment were specified and reported; the control group (if present) were similar in baseline factors; all participants enrolled were accounted for in follow-up; confidence intervals (CIs) or P-values were reported for numerical results; and work activity or disability status were reported. The second checklist evaluated study design (prospective longitudinal versus cross-sectional), sufficient participant numbers, well-matched groups, and well-validated measurement instruments. The third checklist was used to assess RCTs. This examined methods of randomisation, blinding and withdrawals. One reviewer undertook the quality assessment and a second reviewer checked for accuracy. Any disagreements were resolved by discussion.
Data extraction One reviewer extracted the data and a second reviewer checked for accuracy. Any discrepancies were resolved prior to data entry. Impairment scale results were recorded for baseline and follow-up observations. These were categorised according to the impairment domain categories of cognitive, symptoms, exercise, functional, general health, mental or physical health. For each study a maximum of three scales in each of the domains were reported. The scales chosen for extraction were those with the highest number of patients evaluated, those with group means and measures of dispersion, and those with named scales that had been published or validated. When the total and component scales were reported within a single domain, the total was extracted preferentially.
Methods of synthesis How were the studies combined?The studies were grouped according to the type of intervention assessed and combined in a narrative discussion.
How were differences between studies investigated?Differences between the studies were briefly discussed according to the different interventions, study designs and outcome measures.
Results of the review Fifty-three studies (n=4,558) were included in the whole review. Fourteen studies (1,348 participants) evaluated an intervention. The study designs were not reported.
The interventions assessed in the review were behavioural (4 studies), psychiatric (2 studies), drug therapy (5 studies), occupational or physiotherapy ( 2 studies), or mixed (4 studies). There were too few studies of any single intervention with any specific impairment domains to allow any assessment of association. Only 4 studies reported employment at baseline and follow-up after an intervention (3 to 42 months after baseline), and the following summary of the results are based on these 4 studies. The percentage of patients employed ranged from 0 to 39% at baseline and from 44 to 53% at follow-up. The interventions associated with increased employment were individualised rehabilitation programmes, cognitive-behaviour therapy and exercise therapy. No comparisons between the studies could be drawn, however, owing to differences in study design, duration of follow-up and types of intervention. Two further studies reported employment at baseline and follow-up, but had no intervention. Both of these studies showed worsening of employment outcomes at follow-up.
Authors' conclusions For questions of disability and employment in CFS, the limitations in the current literature are extensive. Methodologically rigorous, longitudinal and interventional studies are needed to determine baseline characteristics that are associated with the inability to work and interventions that are effective in restoring the ability to work in CSF populations.
CRD commentary The overall review question was very broad, but had been defined in terms of the participants, outcome measures and study designs. No a priori inclusion criteria had been determined for the interventions that would be assessed. Several sources were searched for relevant studies, but no efforts were made to minimise either language or publication bias; other relevant studies might, therefore, have been missed. Since it was not reported how the studies were selected for the review, it is not known whether any bias or errors might have been introduced. Appropriate methods were, however, used to assess the quality of the included studies and to extract the data.
Adequate details of the individual included studies were not provided, therefore it is impossible for the reader to assess whether the conclusions reflect the evidence reviewed. The studies were combined in a narrative, and differences between the studies were briefly explored. Overall, due to the lack of clarity in the review methods and inadequate details of the primary studies, it is unclear whether the authors' conclusions are reliable.
Implications of the review for practice and research Practice: The author's stated that a routine functional capacity evaluation should prove useful in defining what a patient can and cannot do, and as an objective measure of change over time, with or without specific interventions.
Research: The authors stated that methodologically rigorous, longitudinal and interventional studies are needed to determine baseline characteristics that are associated with the inability to work and interventions that are effective in restoring the ability to work.
Funding Agency for Healthcare Research and Quality, contract number 290-97-0016.
Bibliographic details Ganz N, Frame D, Estok R, Stone L, Ludensky V. Systematic review of the current literature related to disability and chronic fatigue syndrome. Rockville, MD, USA: Agency for Healthcare Research and Quality. Evidence Report/Technology Assessment; 66. 2002 Other publications of related interest Ross SD, Estok RP, Frame D, Stone LR, Ludensky V, Levine CB. Disability and chronic fatigue syndrome: a focus on function. Arch Intern Med 2004;164:1098-107.
Indexing Status Subject indexing assigned by CRD MeSH Disability Evaluation; Fatigue Syndrome, Chronic /diagnosis /physiopathology /therapy; Treatment Outcome AccessionNumber 12003008339 Date bibliographic record published 31/05/2006 Date abstract record published 31/05/2006 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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