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      Judging the quality of evidence in reviews of prognostic factor research: adapting the GRADE framework


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          Prognosis research aims to identify factors associated with the course of health conditions. It is often challenging to judge the overall quality of research evidence in systematic reviews about prognosis due to the nature of the primary studies. Standards aimed at improving the quality of primary studies on the prognosis of health conditions have been created, but these standards are often not adequately followed causing confusion about how to judge the evidence.


          This article presents a proposed adaptation of Grading of Recommendations Assessment, Development and Evaluation (GRADE), which was developed to rate the quality of evidence in intervention research, to judge the quality of prognostic evidence.


          We propose modifications to the GRADE framework for use in prognosis research along with illustrative examples from an ongoing systematic review in the pediatric pain literature. We propose six factors that can decrease the quality of evidence (phase of investigation, study limitations, inconsistency, indirectness, imprecision, publication bias) and two factors that can increase it (moderate or large effect size, exposure-response gradient).


          We describe criteria for evaluating the potential impact of each of these factors on the quality of evidence when conducting a review including a narrative synthesis or a meta-analysis. These recommendations require further investigation and testing.

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          Most cited references25

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          The global burden of headache: a documentation of headache prevalence and disability worldwide.

          This study, which is a part of the initiative 'Lifting The Burden: The Global Campaign to Reduce the Burden of Headache Worldwide', assesses and presents all existing evidence of the world prevalence and burden of headache disorders. Population-based studies applying International Headache Society criteria for migraine and tension-type headache, and also studies on headache in general and 'chronic daily headache', have been included. Globally, the percentages of the adult population with an active headache disorder are 46% for headache in general, 11% for migraine, 42% for tension-type headache and 3% for chronic daily headache. Our calculations indicate that the disability attributable to tension-type headache is larger worldwide than that due to migraine. On the World Health Organization's ranking of causes of disability, this would bring headache disorders into the 10 most disabling conditions for the two genders, and into the five most disabling for women.
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            The existence of publication bias and risk factors for its occurrence.

            Publication bias is the tendency on the parts of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Much of what has been learned about publication bias comes from the social sciences, less from the field of medicine. In medicine, three studies have provided direct evidence for this bias. Prevention of publication bias is important both from the scientific perspective (complete dissemination of knowledge) and from the perspective of those who combine results from a number of similar studies (meta-analysis). If treatment decisions are based on the published literature, then the literature must include all available data that is of acceptable quality. Currently, obtaining information regarding all studies undertaken in a given field is difficult, even impossible. Registration of clinical trials, and perhaps other types of studies, is the direction in which the scientific community should move.
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              Systematic reviews of evaluations of prognostic variables.


                Author and article information

                Syst Rev
                Syst Rev
                Systematic Reviews
                BioMed Central
                5 September 2013
                : 2
                : 71
                [1 ]Centre for Pediatric Pain Research, IWK Health Centre, 5850/5980 University Avenue, PO Box 9700, Halifax, Nova Scotia B3K 6R8, Canada
                [2 ]Department of Community Health and Epidemiology, Dalhousie University, 5790 University Avenue, Halifax, Nova Scotia B3H 1V7, Canada
                [3 ]Hospital for Sick Children, Lawrence S Bloomberg Faculty of Nursing, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
                [4 ]Department of Psychology and Neuroscience, Dalhousie University, PO Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
                [5 ]Department of Psychiatry, Dalhousie University, 5909 Veterans' Memorial Lane, 8th Floor, Abbie J. Lane Memorial Building, QEII Health Sciences Centre, Halifax, Nova Scotia B3H 2E2, Canada
                [6 ]Capital District Health Authority, Research and Innovation, Centre for Clinical Research Building, 117-5790 University Avenue, Halifax, Nova Scotia B3H 1V7, Canada
                Copyright © 2013 Huguet et al.; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                : 24 April 2013
                : 20 August 2013

                Public health
                grade,prognosis,quality of evidence
                Public health
                grade, prognosis, quality of evidence


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