Levels of evidence in the European Society of Cardiology Guidelines: Gaps in knowledge?

Abstract

In the present issue, the paper from van Dijk and colleagues is published without changes after the usual peer reviewing process and it truly reflects the opinions of the authors as they were independently expressed. This editorial choice is not due only to the indisputable interest of the concepts expressed, but also to the decision to publish ideas originated in the Cardiological Community that we hope will generate further contributions, responses and letters. The paper is contributing to the important debate on the recommendations and their levels of evidences reported by the European Guidelines, developed under the umbrella of the European Society of Cardiology (ESC). There is no doubt that Guidelines preparation and update constitutes one of the pillars of the ESC, and groups of experts in the field from across Europe are commissioned to write and review documents according to a structured process that extends over a two-year period. This process finally involves around 100 experts and influences the care provided to millions of people worldwide. In recent years guidelines from both sides of the Atlantic have increasingly been criticized for the limited amount of evidence underlying many of their recommendations. Multiple systematic analyses have shown that a limited number (<15%) of the recommendations in European and American cardiovascular guidelines are supported by evidence from multiple randomized controlled trials (RCTs) and meta-analyses. Although very relevant, the meaning of these findings can remain largely unclear as they lacked a detailed breakdown to where (e.g. therapeutic versus diagnostic recommendations) the suggested lack of evidence is most problematic, unexpected, or potentially solvable. To know which paucities in the evidence base are problematic and where to focus improvement efforts to them, it is necessary to identify areas of recommendations not supported by high-quality evidence and identify the underlying reasons. To reveal where gaps exist in the current cardiovascular evidence base, and allow better interpretation of the evidence underlying recommendations, van Dijk and colleagues performed a really valuable work trying to identify which types of recommendations (e.g. therapeutic or diagnostic) and which recommended actions (e.g. pharmaceutical intervention or non-invasive imaging) are supported by which level of evidence (LoE) in the Guidelines of the ESC. They observed that with a median of 128 recommendations per guideline, most recommendations were of class I (47.7%), followed by class II (44.7%) and only 7.6% class III. However, only 14.1% of the recommendations are supported by multiple RCTs or meta-analysis (LoE A). Moreover the evidence levels supporting recommendations vary widely per: