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


METHODS
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.


RESULTS
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.


CONCLUSIONS
All of the currently used approaches to grading levels of evidence and the strength of recommendations have important shortcomings.
Atkins
David
D
Center for Practice and Technology Assessment, Agency for Healthcare Research and Quality, 540 Gaither Rd. Rockville, MD 20852, USA. DAtkins@AHRQ.GOV
Eccles
Martin
M
Flottorp
Signe
S
Guyatt
Gordon H
GH
Henry
David
D
Hill
Suzanne
S
Liberati
Alessandro
A
O'Connell
Dianne
D
Oxman
Andrew D
AD
Phillips
Bob
B
Schünemann
Holger
H
Edejer
Tessa Tan-Torres
TT
Vist
Gunn E
GE
Williams
John W
JW
D026683:Advisory Committees; D003659:Decision Making, Organizational; D019317:Evidence-Based Medicine / Q000145:classification / Q000592:standards*; D006302:Health Services Research; D006801:Humans; D017410:Practice Guidelines as Topic / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D013597:Systems Analysis; D014481:United States; D016270:United States Agency for Healthcare Research and Quality