Durability of Class I American College of Cardiology/American Heart Association Clinical Practice Guideline Recommendations

Study Questions:

What is the durability of Class I (“procedure/treatment should be performed/administered”) American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations?


Four independent reviewers analyzed 11 ACC/AHA guidelines published between 1998 and 2007, and revised between 2006 and 2013. All Class I recommendations from the first version of each guideline were abstracted, and corresponding recommendations in the subsequent version were identified. Recommendations replaced by less determinate or contrary recommendations were identified as having been downgraded or reversed; recommendations for which no corresponding item could be identified were classified as having been omitted. Differences in the durability of recommendations according to guideline topic and underlying Level of Evidence (LOE) were tested using bivariable hypothesis tests and conditional logistic regression.


Of 619 index recommendations, 495 (80.0%; 95% confidence interval [CI], 76.6%-83.1%) were retained in the subsequent guideline version, 57 (9.2%; 95% CI, 7.0%-11.8%) were downgraded or reversed, and 67 (10.8%; 95% CI, 8.4%-13.3%) were omitted. The percentage of recommendations retained varied across guidelines, from 15.4% (95% CI, 1.9%-45.4%) to 94.1% (95% CI, 80.3%-99.3%; p < 0.001). Among recommendations with available information on LOE, 90.5% (95% CI, 83.2%-95.3%) of recommendations supported by multiple randomized studies were retained, compared to 81.0% (95% CI, 74.8%-86.3%) of recommendations supported by one randomized trial or observational data and 73.7% (95% CI, 65.8%-80.5%) of recommendations supported by opinion (p = 0.001). After accounting for guideline-level factors, the probability of being downgraded, reversed, or omitted was greater for recommendations based on opinion (odds ratio, 3.14; 95% CI, 1.69-5.85; p < 0.001) or on one trial or observational data (odds ratio, 3.49; 95% CI, 1.45-8.41; p = 0.005) compared to recommendations based on multiple trials.


The durability of Class I cardiology guideline recommendations for procedures and treatments promulgated by the ACC/AHA varied across individual guidelines and LOEs. Downgrades, reversals, and omissions were most common among recommendations not supported by multiple randomized studies.


This is a brilliant if somewhat obvious study. ACC/AHA guidelines place greatest weight on conclusions from multiple randomized trials (LOE A), with progressively less weight placed on single randomized trials (LOE B) and case studies or consensus opinion (LOE C). Recommendations made with LOE A are unlikely to be reversed or diluted without multiple additional randomized trials, whereas recommendations made with lower levels of existing evidence could be expected to change with additional data or with change in consensus opinion. The take-home messages from this welcomed study could be that medicine evolves, that guidelines are not timeless, and that more data supporting a recommendation probably portends greater durability of that recommendation.

Keywords: Mitochondrial Diseases, Ophthalmoplegia, Body Weight, Guideline Adherence, Biological Evolution, Angioplasty, Balloon, Coronary, United States

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