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. 2019 Mar 19;321(11):1069-1080.
doi: 10.1001/jama.2019.1122.

Levels of Evidence Supporting American College of Cardiology/American Heart Association and European Society of Cardiology Guidelines, 2008-2018

Alexander C Fanaroff  1 , Robert M Califf  2   3   4 , Stephan Windecker  5 , Sidney C Smith Jr  6 , Renato D Lopes  1
Affiliations

Levels of Evidence Supporting American College of Cardiology/American Heart Association and European Society of Cardiology Guidelines, 2008-2018

Alexander C Fanaroff et al. JAMA. .

Abstract

Importance: Clinical decisions are ideally based on evidence generated from multiple randomized controlled trials (RCTs) evaluating clinical outcomes, but historically, few clinical guideline recommendations have been based entirely on this type of evidence.

Objective: To determine the class and level of evidence (LOE) supporting current major cardiovascular society guideline recommendations, and changes in LOE over time.

Data sources: Current American College of Cardiology/American Heart Association (ACC/AHA) and European Society of Cardiology (ESC) clinical guideline documents (2008-2018), as identified on cardiovascular society websites, and immediate predecessors to these guideline documents (1999-2014), as referenced in current guideline documents.

Study selection: Comprehensive guideline documents including recommendations organized by class and LOE.

Data extraction and synthesis: The number of recommendations and the distribution of LOE (A [supported by data from multiple RCTs or a single, large RCT], B [supported by data from observational studies or a single RCT], and C [supported by expert opinion only]) were determined for each guideline document.

Main outcomes and measures: The proportion of guideline recommendations supported by evidence from multiple RCTs (LOE A).

Results: Across 26 current ACC/AHA guidelines (2930 recommendations; median, 121 recommendations per guideline [25th-75th percentiles, 76-155]), 248 recommendations (8.5%) were classified as LOE A, 1465 (50.0%) as LOE B, and 1217 (41.5%) as LOE C. The median proportion of LOE A recommendations was 7.9% (25th-75th percentiles, 0.9%-15.2%). Across 25 current ESC guideline documents (3399 recommendations; median, 130 recommendations per guideline [25th-75th percentiles, 111-154]), 484 recommendations (14.2%) were classified as LOE A, 1053 (31.0%) as LOE B, and 1862 (54.8%) as LOE C. When comparing current guidelines with prior versions, the proportion of recommendations that were LOE A did not increase in either ACC/AHA (median, 9.0% [current] vs 11.7% [prior]) or ESC guidelines (median, 15.1% [current] vs 17.6% [prior]).

Conclusions and relevance: Among recommendations in major cardiovascular society guidelines, only a small percentage were supported by evidence from multiple RCTs or a single, large RCT. This pattern does not appear to have meaningfully improved from 2008 to 2018.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Fanaroff reported support from a career development grant from the American Heart Association (17FTF33661087). Dr Califf reported serving as the Commissioner of Food and Drugs for the US Food and Drug Administration from February 2016 to January 2017; serving as Deputy Commissioner for Medical Products and Tobacco for the US Food and Drug Administration from February 2015 to January 2016; serving on the corporate board for Cytokinetics and as board chair for the People-Centered Research Foundation; and receiving consulting fees from Merck, Biogen, Genentech, Eli Lilly, and Boehringer Ingelheim. Dr Windecker reported research and educational grants to his institution from Abbott, Amgen, Bayer, Boston Scientific, Biotronik, Edwards Lifesciences, Medtronic, St Jude, and Terumo. Dr Lopes reported receiving research grants from Bristol-Myers Squibb, GlaxoSmithKline, Medtronic, Pfizer, and Sanofi and receiving personal fees from Amgen, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, GlaxoSmithKline, Medtronic, Pfizer, and Sanofi. Dr Smith reported no disclosures.

Figures

Figure 1.
Figure 1.. Proportion of Recommendations Classified as Level of Evidence A Overall and by Class of Recommendation in the ACC/AHA and ESC Guidelines
Although a greater proportion of class I (“should do”) and class III (“should not do”) recommendations are supported by level of evidence (LOE) A evidence and some subspecialties have a greater proportion of LOE A recommendations than others, less than 15% of guideline recommendations in all subspecialties are supported by LOE A evidence. Missing bars represent subspecialty area/class combinations for which 0% of recommendations are classified as LOE A. ACC/AHA indicates American College of Cardiology/American Heart Association; ESC, European Society of Cardiology.
Figure 2.
Figure 2.. Proportion of Recommendations With Level of Evidence A, B, and C in Current and Prior Guideline Documents
In all cases, a current guideline document is compared with its predecessor covering the same disease or topic area. ACC/AHA indicates American College of Cardiology/American Heart Association; CVD, cardiovascular disease; ESC, European Society of Cardiology; LOE, level of evidence; NSTE-ACS, acute coronary syndrome without ST-segment elevation; STEMI, ST-segment elevation myocardial infarction.
Figure 3.
Figure 3.. Proportion of Recommendations With Level of Evidence A by Subspecialty Area in Topic Areas Covered by Both a Current American College of Cardiology/American Heart Association and European Society of Cardiology Guideline Document
Numbers within the bars represent the total number of recommendations in each subspecialty area. In most subspecialty areas, a greater proportion of recommendations in European Society of Cardiology guidelines are supported by level of evidence (LOE) A evidence.
Figure 4.
Figure 4.. Proportion of Recommendations by Class and Level of Evidence in Current and Prior ACC/AHA and ESC Guidelines
“Heat maps” shown represent 26 current and 16 prior American College of Cardiology/American Heart Association (ACC/AHA) guidelines and 25 current and 16 prior European Society of Cardiology (ESC) guidelines. Light blue squares represent low percentages; darker blue squares, high percentages.
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