Clinical practice guideline recommendations related to screening and treatment can change markedly over time as new evidence about best practices and clinical outcomes of various treatments emerges. In a first-of-its-kind study, Penn Medicine researchers examined high-level recommendations published by the American College of Cardiology (ACC) and the American Heart Association (AHA) between 1998 and 2007 and found that recommendations which were supported by multiple randomized controlled trials were the most “durable” and least likely to change over time. Their work will be published in JAMA.

A Penn research team led by Mark D. Neuman, MD, MSc, assistant professor of Anesthesiology and Critical Care and Senior Fellow in the Leonard David Institute of Health Economics, analyzed changes over time in over 600 Class I ACC/AHA recommendations, each of which recommended strongly in favor of a particular treatment or procedure related to cardiovascular disease.  

Based on comparisons of serial editions of ACC/AHA guidelines, the authors observed that 4 out of 5 Class I recommendations remained valid across two guideline editions; however, they also noted that 1 out of every 5 Class I recommendations was either downgraded to a less certain status, reversed so as to recommend against a previously endorsed treatment, or omitted entirely.

Neuman and colleagues also found the odds of a downgrade, reversal, or omission to be more than three times greater among recommendations based on retrospective studies, case reports, or expert opinion versus randomized controlled trials. 

While the study was not designed to examine the specific reasons that the individual recommendations were downgraded, supplemental analyses suggested that it was uncommon for recommendations to be downgraded as a result of the emergence of new research studies. Instead, Neuman and colleagues found that many of the downgrades in recommendations that they observed may have come from changes over time in how expert physicians interpreted existing medical research.

“Clinical practice guidelines are used by health care providers to make decisions about treatments for individual patients, and by hospitals, regulators, and insurers to develop quality measures,” says Neuman. "Our study provides new information about the durability of guideline recommendations over time that can help patients, clinicians, administrators, and regulators make better choices about how guideline recommendations can be used to improve patient outcomes.”

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