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P U B L I S H E D B Y E L S E V I E R

CLINICAL GUIDELINES

Further Evolution of theACC/AHA Clinical Practice Guideline

Recommendation Classification System A Report of the American College of Cardiology/American Heart AssociationTask Force on Clinical Practice Guidelines

ACC/AHA Task Jonathan L. Halperin, MD, FACC, FAHA, Chair

Force Members Glenn N. Levine, MD, FACC, FAHA, Chair-Elect

Sana M. Al-Khatib, MD, MHS, FACC, FAHAKim K. Birtcher, PHARMD, AACCBiykem Bozkurt, MD, PHD, FACC, FAHARalph G. Brindis, MD, MPH, MACCJoaquin E. Cigarroa, MD, FACCLesley H. Curtis, PHD, FAHA

The ACC/AHA Recommendation System described in this document (T

Trustees and Executive Committee and the American Heart Association Sci

June 2015.

The American College of Cardiology requests that this document be cited

Brindis RG, Cigarroa JE, Curtis LH, Fleisher LA, Gentile F, Gidding S, Hlatky M

of the ACC/AHA clinical practice guideline recommendation classification

Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol 20

This article has been copublished in Circulation.

Copies: This document is available on the World Wide Web sites of the Am

Association (http://my.americanheart.org). For copies of this document, ple

(reprints@elsevier.com).

Permissions: Multiple copies, modification, alteration, enhancement, and

permission of the American College of Cardiology. Requests may be compl

author-agreement/obtaining-permission).

Lee A. Fleisher, MD, FACC, FAHAFederico Gentile, MD, FACCSamuel Gidding, MD, FAHAMark A. Hlatky, MD, FACCJohn Ikonomidis, MD, PHD, FAHAJosé Joglar, MD, FACC, FAHASusan J. Pressler, PHD, RN, FAHADuminda N. Wijeysundera, MD, PHD

For 3 decades, the American College of Cardiology (ACC) andthe American Heart Association (AHA) have jointly developedclinical practice guidelines in an effort to align patient carewith scientific evidence (1). The “2015 ACC/AHA/HRS Guide-line on the Management of Patients With SupraventricularTachycardia” (2) introduces the latest recommendation clas-sification system (Table 1), which has continued to evolve. Thepresent brief commentary summarizes and explains thechanges incorporated in the current scheme. More detailedreviews of the evolution of ACC/AHA guideline methodologyhave been published (1,3–5).

CLASSES OF RECOMMENDATION AND

LEVELS OF EVIDENCE

Guideline recommendations are categorized by the Class ofRecommendation (COR) and Level of Evidence (LOE). The CORreflects the magnitude of benefit over risk and corresponds tothe strength of the recommendation. Class I recommendationsare strong and indicate that the treatment, procedure, orintervention is useful and effective and should be performedor administered for most patients under most circumstances.Class II recommendations are weaker, denoting a lower degree

able 1) was approved by the American College of Cardiology Board of

ence Advisory and Coordinating Committee and Executive Committee in

as follows: Halperin JL, Levine GN, Al-Khatib SM, Birtcher KK, Bozkurt B,

A, Ikonomidis J, Joglar J, Pressler SJ, Wijeysundera DN. Further evolution

system: a report of the American College of Cardiology/American Heart

16;67:1572–4.

erican College of Cardiology (http://www.acc.org) and the American Heart

ase contact Elsevier Reprint Department via fax (212-633-3820) or e-mail

/or distribution of this document are not permitted without the express

eted online via the Elsevier site (http://www.elsevier.com/about/policies/

TABLE 1ACC/AHA Recommendation System: Applying Class of Recommendation and Level of Evidence to Clinical Strategies,Interventions, Treatments, or Diagnostic Testing in Patient Care* (Updated August 2015)

J A C C V O L . 6 7 , N O . 1 3 , 2 0 1 6 Halperin et al.A P R I L 5 , 2 0 1 6 : 1 5 7 2 – 4 The COR/LOE Evolution: Task Force Statement

1573

of benefit in proportion to risk. Benefit is generally greaterfor Class IIa (moderate) recommendations and smaller forClass IIb (weak) recommendations, for which benefit onlymarginally exceeds risk. A COR of IIb suggests thatimplementation should be selective and based on carefulconsideration of individual patient factors and, for inva-sive procedures, available expertise. Class III is assignedwhen actions are specifically not recommended, eitherbecause studies have found no evidence of benefit orbecause the intervention causes harm.

The LOE denotes the confidence in or certainty of theevidence supporting the recommendation, based on thetype, size, quality, and consistency of pertinent researchfindings. In general, for pharmacological treatments ortherapeutic procedures, data from randomized controlledtrials provide a higher LOE than do observational or retro-spective studies, but other considerations apply to recom-mendations involving diagnostic testing, population-basedinterventions, or lifestyle modifications. High-quality, con-cordant evidence from more than 1 adequately powered

Halperin et al. J A C C V O L . 6 7 , N O . 1 3 , 2 0 1 6

The COR/LOE Evolution: Task Force Statement A P R I L 5 , 2 0 1 6 : 1 5 7 2 – 4

1574

randomized controlled trial, meta-analyses of high-qualitytrials, or randomized controlled trial data corroborated byhigh-quality registry or practice-based studies qualifies asLOE A. Moderate-quality or less convincing evidence basedon 1 or more trials, meta-analyses of moderate-qualitystudies, or data derived exclusively from registries orother sources that have not been externally validated areassigned LOE B and are now further delineated accordingto whether the evidence derives from randomized (B-R) ornonrandomized studies (B-NR). When firm scientific sup-port for a recommendation is not available, the evidence isdesignated as LOE C. There is now a new subcategorizationof lower-quality evidence, assigned either because dataare limited (C-LD) (i.e., based on physiological preclinicalstudies, case reports, or studies with methodologicaldeficiencies in design or execution) or because the recom-mendation is based on clinical experience and a consensusof expert opinion (C-EO).

The COR and LOE are assessed independently. When arecommendation is designated as LOE C, that does notimply that the recommendation is weak. In some cases,clinical benefit is self-evident, and the intervention isunlikely to undergo randomized study. Where availabledata are weak, conflicting, or absent, recommendationsbased on this relatively low level of evidence may provideguidance for patient care when clinicians need it most (3).Nevertheless, because in the past a relatively high pro-portion of recommendations were based on LOE C and amodest percentage were based on LOE A (6), greateremphasis is now placed on formulating recommendationssupported by higher-quality evidence and limiting thosebased on lower-quality evidence.

EVOLUTION IN CONTEXT

These modifications align with recommendationspromulgated by the Institute of Medicine in 2011 (7,8) andfacilitate comparison of the strength (or COR) and quality(or LOE) with categories used by other guideline de-velopers. The new scheme is intended mainly to increasethe granularity and precision of the ACC/AHA system,while broadly retaining the COR and LOE categoriesfamiliar to readers of both U.S. and European cardiovas-cular guidelines. The changes have been implemented aspart of the continuous evolution of guideline developmentto ensure comprehensive, objective assessment of allavailable evidence and delivery of recommendations in auniform format that is most useful at the point of care.Among the many remaining challenges are the develop-ment of more objective and standardized criteria forassessment of the quality of evidence, incorporation ofcost and health economic methodology into guidelines,formulation of more efficient processes for revising andupdating recommendations as new evidence emerges, andcreation of tools to integrate context-sensitive guidelinerecommendations with electronic health records (3,9).The structured system for classifying the strength ofclinical recommendations and quality of the evidencesupporting them spans all of these ongoing initiatives andremains at the heart of the guidelines.

Comprehensive disclosure information for the taskforce is available at http://www.acc.org/guidelines/about-guidelines-and-clinical-documents/guidelines-and-documents-task-forces.

R EF E RENCE S

1. Jacobs AK, Kushner FG, Ettinger SM, et al. ACCF/AHA clinical practice guideline methodology summitreport: a report of the American College of CardiologyFoundation/American Heart Association Task Force onPractice Guidelines. J Am Coll Cardiol. 2013;61:213–65.

2. Page RL, Joglar JA, Al-Khatib SM, et al. 2015ACC/AHA/HRS guideline for the management of adultpatients with supraventricular tachycardia: a report ofthe American College of Cardiology/American HeartAssociation Task Force on Clinical Practice Guidelinesand the Heart Rhythm Society. J Am Coll Cardiol. 2015;67:1573–616.

3. Jacobs AK, Anderson JL, Halperin JL. The evolutionand future of ACC/AHA clinical practice guidelines:a 30-year journey: a report of the American Collegeof Cardiology/American Heart Association Task Forceon Practice Guidelines. J Am Coll Cardiol. 2014;64:1373–84.

4. Gibbons RJ, Smith S, Antman E. American College ofCardiology/American Heart Association clinical practiceguidelines: part I: where do they come from? Circula-tion. 2003;107:2979–86.

5. Gibbons RJ, Smith SC Jr, Antman E. American Col-lege of Cardiology/American Heart Association clinicalpractice guidelines: part II: evolutionary changes in acontinuous quality improvement project. Circulation.2003;107:3101–7.

6. Tricoci P, Allen JM, Kramer JM, et al. Scientific evi-dence underlying the ACC/AHA clinical practiceguidelines. JAMA. 2009;301:831–41.

7. Committee on Standards for Developing Trust-worthy Clinical Practice Guidelines, Institute ofMedicine (U.S.). Clinical Practice Guidelines WeCan Trust. Washington, DC: National AcademiesPress; 2011.

8. Committee on Standards for Systematic Reviews ofComparative Effectiveness Research, Institute ofMedicine (U.S.). Finding What Works in Health Care:Standards for Systematic Reviews. Washington, DC:National Academies Press; 2011.

9. Anderson JL, Heidenreich PA, Barnett PG, et al.ACC/AHA statement on cost/value methodology inclinical practice guidelines and performance measures:a report of the American College of Cardiology/American Heart Association Task Force on PerformanceMeasures and Task Force on Practice Guidelines. J AmColl Cardiol. 2014;63:2304–22.

KEY WORDS ACC/AHA Clinical PracticeGuideline, evidence-based medicine, health care,methodology