Limited data exists on how frequently guidelines change over time. This study examined how frequently class I recommendations (“procedure/treatment should be performed/administered”) in ACC/AHA guidelines were downgraded to a lower class over time. Four independent reviewers examined 619 class I ACC/AHA recommendations in 11 guidelines released between 1998-2007 and revised between 2006-2013. Overall, 495 recommendations (80.0%; 95% CI 76.6% – 83.1%) were retained in subsequent versions, 57 (9.2%; 95% 7.0% – 11.8%) were downgraded or reversed, and 67 (10.8%; 95% CI 8.4% – 13.3%) were omitted. Compared to recommendations based on multiple randomized trials, the probability of a guideline recommendation being omitted, reversed or downgraded was higher for recommendations based on opinion (OR 3.14; 95% CI 1.69-5.85) or on 1 trial or observational data (OR 3.49; 95% CI 1.45-8.40).

Conclusion: 1 in 5 class I guideline recommendations are omitted, reversed, or downgraded over time.  These changes in guidelines are far more common for recommendations based on little to no randomized trial data.  These findings question the wisdom of class I indications in the absence of solid evidence to support the recommendation.

 Summarized by Supriya Shore and Steven M. Bradley

• Neuman MD, Goldstein JN, Cirullo MA, Schwartz JS. Durability of class I American College of Cardiology/American Heart Association clinical practice guideline recommendations. JAMA. May 28 2014;311(20):2092-2100.