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      Systems for grading the quality of evidence and the strength of recommendations I: Critical appraisal of existing approaches The GRADE Working Group


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          A number of approaches have been used to grade levels of evidence and the strength of recommendations. The use of many different approaches detracts from one of the main reasons for having explicit approaches: to concisely characterise and communicate this information so that it can easily be understood and thereby help people make well-informed decisions. Our objective was to critically appraise six prominent systems for grading levels of evidence and the strength of recommendations as a basis for agreeing on characteristics of a common, sensible approach to grading levels of evidence and the strength of recommendations.


          Six prominent systems for grading levels of evidence and strength of recommendations were selected and someone familiar with each system prepared a description of each of these. Twelve assessors independently evaluated each system based on twelve criteria to assess the sensibility of the different approaches. Systems used by 51 organisations were compared with these six approaches.


          There was poor agreement about the sensibility of the six systems. Only one of the systems was suitable for all four types of questions we considered (effectiveness, harm, diagnosis and prognosis). None of the systems was considered usable for all of the target groups we considered (professionals, patients and policy makers). The raters found low reproducibility of judgements made using all six systems. Systems used by 51 organisations that sponsor clinical practice guidelines included a number of minor variations of the six systems that we critically appraised.


          All of the currently used approaches to grading levels of evidence and the strength of recommendations have important shortcomings.

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          Most cited references25

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          The periodic health examination. Canadian Task Force on the Periodic Health Examination.

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            Users' guides to the medical literature. IX. A method for grading health care recommendations. Evidence-Based Medicine Working Group.

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              Data collection instrument and procedure for systematic reviews in the Guide to Community Preventive Services. Task Force on Community Preventive Services.

              A standardized abstraction form and procedure was developed to provide consistency, reduce bias, and improve validity and reliability in the Guide to Community Preventive Services: Systematic Reviews and Evidence-Based Recommendations (the Guide). The content of the abstraction form was based on methodologies used in other systematic reviews; reporting standards established by major health and social science journals; the evaluation, statistical and meta-analytic literature; expert opinion and review; and pilot-testing. The form is used to classify and describe key characteristics of the intervention and evaluation (26 questions) and assess the quality of the study's execution (23 questions). Study procedures and results are collected and specific threats to the validity of the study are assessed across six categories (intervention and study descriptions, sampling, measurement, analysis, interpretation of results and other execution issues). Each study is abstracted by two independent reviewers and reconciled by the chapter development team. Reviewers are trained and provided with feedback. What to abstract and how to summarize the data are discretionary choices that influence conclusions drawn on the quality of execution of the study and its effectiveness. The form balances flexibility for the evaluation of papers with different study designs and intervention types with the need to ask specific questions to maximize validity and reliability. It provides a structured format that researchers and others can use to review the content and quality of papers, conduct systematic reviews, or develop manuscripts. A systematic approach to developing and evaluating manuscripts will help to promote overall improvement of the scientific literature.

                Author and article information

                BMC Health Serv Res
                BMC Health Services Research
                BioMed Central (London )
                22 December 2004
                : 4
                : 38
                [1 ]Center for Practice and Technology Assessment, Agency for Healthcare Research and Quality, 540 Gaither Rd. Rokville, MD 20852, USA
                [2 ]Centre for Health Services Research, University of Newcastle upon Tyne, 21 Claremont Place, Newcastle upon Tyne NE2 4AA, UK
                [3 ]Informed Choice Research Department, Norwegian Health Services Research Centre, Pb. 7004 St. Olavs Plass, 0130 Oslo, Norway
                [4 ]Departments of Clinical Epidemiology and Biostatistics and Medicine, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada
                [5 ]Department of Clinical Pharmacology, Faculty of Medicine and Health Sciences, University of Newcastle, Level 5, New Med 2 Building, Newcastle Mater Hospital, Waratah, NSW 2298, Australia
                [6 ]Department of Oncology and Hematology, Università di Modena e Reggio Emilia, Azienda Ospedaliera Policlinico, Via dal Pozzo 41, 41100 Modena, Italia and Centro per la Valutazione della Efficacia della Assistenza Sanitaria (CeVEAS), Modena, Italy
                [7 ]Cancer Epidemiology Research Unit, Cancer Research and Registers Division, The Cancer Council NSW, PO Box 572, Kings Cross NSW 1340, Australia
                [8 ]Centre for Evidence-based Medicine, University Department of Psychiatry, Warneford Hospital, Oxford OX3 7JX, UK
                [9 ]Departments of Medicine and Social & Preventive Medicine, University at Buffalo, State University of New York, ECMC-CC142, 462 Grinder St, Buffalo, NY 14215, USA
                [10 ]Global Programme on Evidence for Health Policy, World Health Organisation, CH-1211 Geneva 27, Switzerland
                [11 ]The Center for Health Services Research in Primary Care, HSR&D, Department of Veterans Affairs Medical Center and Duke University Medical Center, 508 Fulton St., Durham, NC 27705, USA
                Copyright © 2004 Atkins 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.

                : 23 January 2004
                : 22 December 2004
                Research Article

                Health & Social care
                practice guidelines,evidence-based health care,strength of recommendation,levels of evidence,systematic reviews


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