Journal of clinical epidemiology
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Our objective was to develop a framework to identify research gaps from systematic reviews. ⋯ Our framework determines from systematic reviews where the current evidence falls short and why or how the evidence falls short. This explicit identification of research gaps will allow systematic reviews to maximally inform the types of questions that need to be addressed and the types of studies needed to address the research gaps.
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In the GRADE approach, randomized trials start as high-quality evidence and observational studies as low-quality evidence, but both can be rated down if a body of evidence is associated with a high risk of publication bias. Even when individual studies included in best-evidence summaries have a low risk of bias, publication bias can result in substantial overestimates of effect. ⋯ The most popular of these is the funnel plot; all, however, have substantial limitations. Publication bias is likely frequent, and caution in the face of early results, particularly with small sample size and number of events, is warranted.
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Direct evidence comes from research that directly compares the interventions in which we are interested when applied to the populations in which we are interested and measures outcomes important to patients. Evidence can be indirect in one of four ways. First, patients may differ from those of interest (the term applicability is often used for this form of indirectness). ⋯ Thirdly, outcomes may differ from those of primary interest-for instance, surrogate outcomes that are not themselves important, but measured in the presumption that changes in the surrogate reflect changes in an outcome important to patients. A fourth type of indirectness, conceptually different from the first three, occurs when clinicians must choose between interventions that have not been tested in head-to-head comparisons. Making comparisons between treatments under these circumstances requires specific statistical methods and will be rated down in quality one or two levels depending on the extent of differences between the patient populations, co-interventions, measurements of the outcome, and the methods of the trials of the candidate interventions.
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Multicenter Study
The International Classification of Functioning, Disability and Health: development of capacity and performance scales.
There has been no attempt to obtain a continuous summary measure of disability from the checklist of the International Classification of Functioning, Disability and Health (ICF). Our objective was to assess whether valid scales of Capacity and Performance could be developed from the "Activities and Participation" domain of the ICF checklist. ⋯ Our findings support the measurement model, reliability, and validity of the Capacity and Performance scales. Summary measures of functioning based on the ICF can be obtained using these scales, which should facilitate their incorporation in clinical and epidemiological studies.