Challenges in the adjudication of major bleeding events in acute coronary syndrome: a plea for a standardized approach and guidance to adjudication

Potent antithrombotic therapy significantly reduces the risk of recurrent ischaemic events and death in patients with acute coronary syndromes (ACS), inevitably resulting in an increase in iatrogenic bleeding complications1,2 Severe haemorrhagic complications in patients undergoing percutaneous coronary intervention (PCI), and in patients with ACS are associated with short-term mortality and morbidity, prolonged length of stay and greater resource consumption.3–5 Consequently, inclusion of bleeding as a safety endpoint in randomized controlled trials (RCTs) is essential for the assessment of new antithrombotic agents and interventional techniques. In past studies, a large number of bleeding classifications have been used to report bleeding complications (an overview of current bleeding classifications is presented in Supplementary material online, Table S1 ). This variety has hampered direct comparison of incidences of bleeding complications across different trials or even within studies, because reported bleeding incidences may vary widely according to the applied bleeding definition.6,7 To overcome the heterogeneity in bleeding definitions, the Bleeding Academic Research Consortium (BARC) has developed a standardized hierarchical bleeding classification system.8 The prognostic value of BARC defined bleeding complications was recently established in patients undergoing elective PCI, in patients with ACS and in those with ST-segment elevation myocardial infarction (STEMI).9–11 Introduction of standardized bleeding classifications represents a first step to improved interpretation of safety results from clinical trials and registries. Bleeding rates, however, depend on several factors, including how aggressively investigators seek to track bleeding events, and on how definitions are written and applied. Previous studies conducted in similar study populations, using similar treatment strategies, and using identical study methodology have shown great disparities in bleeding incidences, …