Comparative analysis of level of evidence and class of recommendation for 50 clinical practice guidelines released by the European Society of Cardiology from 2011 to 2022

Background: The European Society of Cardiology (ESC) clinical practice guidelines are essential tools for decision-making. Aim: To analyze the level of evidence (LOE) and the class of recommendations in the ESC guidelines released in the last 12 years. Methods: We evaluated 50 ESC guidelines released from 2011 to 2022, related to 27 topics and categorized them into seven macro-groups. We analyzed every recommendation in terms of LOE and class of recommendation, calculating their relative proportions and changes over time in consecutive editions of the same guideline. Results: A total of 6972 recommendations were found, with an increase in number per year over time. Among the 50 ESC guidelines, the proportional distribution of classes of recommendations was 49% for Class I, 29% for Class IIa, 15% for Class IIb, and 8% for Class III. Overall, 16% of the recommendations were classified as LOE A, 31% LOE B and 53% LOE C. The field of preventive cardiology had the largest proportion of LOE A, while the lowest was in the field of valvular, myocardial, pericardial and pulmonary diseases. The overall proportion of LOE A recommendations in the most recent guidelines compared to their prior versions increased from 17% to 20%. Conclusions: The recommendations included in the ESC guidelines widely differ in terms of quality of evidence, with only 16% supported by the highest quality of evidence. Although a slight global increase in LOE A recommendations was observed in recent years, further scientific research efforts are needed to increase the quality of evidence.