title: Grading the strength of a body of evidence when assessing health care interventions: an EPC update.
abstract: OBJECTIVE
  To revise 2010 guidance on grading the strength of evidence (SOE) of the effectiveness of drugs, devices, and other preventive and therapeutic interventions in systematic reviews produced by the Evidence-based Practice Center (EPC) program, established by the US Agency for Healthcare Research and Quality (AHRQ).
  
  
  METHODS
  A cross-EPC working group reviewed authoritative systems for grading SOE [primarily the approach from the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group] and conducted extensive discussions with GRADE and other experts.
  
  
  RESULTS
  Updated guidance continues to be conceptually similar to GRADE. Reviewers are to evaluate SOE separately for each major treatment comparison for each major outcome. We added reporting bias as a required domain and retained study limitations (risk of bias), consistency, directness, and precision (and three optional domains). Additional guidance covers scoring consistency, precision, and reporting bias, grading bodies of evidence with randomized controlled trials and observational studies, evaluating single study bodies of evidence, using studies with high risk of bias, and presenting findings with greater clarity and transparency. SOE is graded high, moderate, low, or insufficient, reflecting reviewers' confidence in the findings for a specific treatment comparison and outcome.
  
  
  CONCLUSIONS
  No single approach for grading SOE suits all reviews, but a more consistent and transparent approach to reporting summary information will make reviews more useful to the broad range of audiences that AHRQ's work aims to reach. EPC working groups will consider ongoing challenges and modify guidance as needed, on issues such as combining trials and observational studies in bodies of evidence, weighting domains, and combining qualitative and quantitative syntheses.
authors.affiliation: Division of Social Policy, Health & Economics Research, RTI International (Research Triangle Institute), PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA. Electronic address: berkman@rti.org.
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Berkman
authors.affiliation: Division of Social Policy, Health & Economics Research, RTI International (Research Triangle Institute), PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA.
authors.forename: Kathleen N
authors.initials: KN
authors.lastname: Lohr
authors.affiliation: Clinical Epidemiology Program, Ottawa Hospital Research Institute, Box 201B, Ottawa Hospital - General campus, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada.
authors.forename: Mohammed T
authors.initials: MT
authors.lastname: Ansari
authors.affiliation: Center for Evidence-Based Medicine, Brown University, School of Public Health, Box G-S121-8, Providence, RI 02912, USA.
authors.forename: Ethan M
authors.initials: EM
authors.lastname: Balk
authors.affiliation: University of Minnesota, School of Public Health, 420 Delaware St SE, MMC 197, Minneapolis, MN 55455, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Kane
authors.affiliation: Pacific Northwest Evidence-based Practice Center, Oregon Health Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
authors.forename: Marian
authors.initials: M
authors.lastname: McDonagh
authors.affiliation: Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburg, PA 15261, USA.
authors.forename: Sally C
authors.initials: SC
authors.lastname: Morton
authors.affiliation: Division of Social Policy, Health & Economics Research, RTI International (Research Triangle Institute), PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA.
authors.forename: Meera
authors.initials: M
authors.lastname: Viswanathan
authors.affiliation: Department of Medicine, and Department of Health Policy and Management, Johns Hopkins University, 624 North Broadway, Room 680A, Baltimore, MD, 21205, USA.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Bass
authors.affiliation: University of Minnesota, School of Public Health, 420 Delaware St SE, MMC 197, Minneapolis, MN 55455, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Butler
authors.affiliation: Division of Social Policy, Health & Economics Research, RTI International (Research Triangle Institute), PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA; Department for Clinical Epidemiology and Evidence-based Medicine, Danube University, Dr. Karl Dorrek Strasse 30, 3500 Krems, Austria.
authors.forename: Gerald
authors.initials: G
authors.lastname: Gartlehner
authors.affiliation: Department of Pediatrics, University of Alberta, ECHA 4-472, 11405-87 Avenue, Edmonton, Alberta, T6G 1C9, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hartling
authors.affiliation: Department of Health Policy, Vanderbilt University, Medical Center, 6th Floor, 2525 West End Avenue, Nashville, TN 37203, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: McPheeters
authors.affiliation: Division of Social Policy, Health & Economics Research, RTI International (Research Triangle Institute), PO Box 12194, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Morgan
authors.affiliation: Evidence-Based Practice Center and Health Technology Assessment Group, ECRI Institute Headquarters, 5200 Butler Pike, Plymouth Meeting, PA 19462, USA.
authors.forename: James
authors.initials: J
authors.lastname: Reston
authors.affiliation: University of North Carolina School of Medicine, 1001 Bondurant Hall, CB# 9535, Chapel Hill, NC 27599, USA.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Sista
authors.affiliation: Center for Health Research, Kaiser Permanente, Northwest, 3800 N. Interstate Avenue, Portland, OR 97227, USA.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Whitlock
authors.affiliation: Center for Evidence and Practice Improvement, Agency for Healthcare Research and Quality, 540 Gaither Road, Rockville, MD 20850, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Chang
mesh_terms: D003695:Delivery of Health Care / Q000592:standards*; D019317:Evidence-Based Medicine; D006801:Humans; D011785:Quality Assurance, Health Care
keywords: Clinical practice guidelines; Evidence-based practice; Health care delivery; Health policy; Methods; Minimally important differences; Optimal information size; Strength of evidence; Systematic reviews