Assessing the Evidence Behind Guidelines in Cardiothoracic Surgery: A Systematic Review.

Background: Clinical practice guidelines are essential for guiding clinical decisions in cardiothoracic surgery. Despite this, the quality of evidence supporting cardiothoracic surgery guidelines has not been formally assessed. This systematic review characterizes the level of evidence underlying current cardiothoracic surgery guidelines. Methods: We extracted recommendations from US professional society guidelines that addressed cardiac or thoracic surgery and used the American College of Cardiology evidence framework. Recommendations were characterized by their level of evidence and assigned a phase of care by 2 independent raters. The primary outcome was the level of evidence across all guidelines, stratified by recommendation strength, phase of care, and disease process. Results: We identified 2 professional societies, American Association for Thoracic Surgery and The Society of Thoracic Surgeons, that published 24 guidelines meeting inclusion criteria. These contained 714 eligible recommendations; 52 (7%) had level A evidence, indicating support from multiple randomized controlled trials or 1 large randomized controlled trial. Of the recommendations classified as strong, 33 (10%) had level A evidence. Perioperative recommendations had the highest proportion of level A support (14%) compared with intraoperative (7%) and nonoperative (1%) recommendations. By disease process, level A evidence ranged from 44% in esophageal guidelines to 0% in coronary artery disease, aorta, and congenital heart disease guidelines. Conclusions: Few clinical practice guidelines in cardiothoracic surgery are supported by high-quality evidence. This highlights a significant evidence gap and the need to strengthen the rigor of evidence generation, particularly for surgical interventions.