Impact of Selection Criteria on Outcomes of Antithrombotic Trials in Acute Coronary Syndromes

Selecting patients of appropriate risk is a seminal element of any clinical trial methodology. However, inappropriate risk markers may result in selecting patients with unintended risk levels. We aimed to review systematically the outcomes of randomized clinical trials of antithrombotics in acute coronary syndromes (ACS) in relation to the inclusion risk markers, dividing them into groups reflecting increased hemodynamic (for example Killip>1, ejection fraction<40%) or bleeding risks (for example renal failure, elderly age). According to our analysis, the trials including increased bleeding risk selection criteria were significantly related to the trial outcome of increased bleeding. Conclusions: Results of antithrombotic trials in ACS may be related to the kind of patients’ selection criteria rather than the drug efficacy/safety. We also provide a conceptual basis for avoiding the pitfalls, which will help future researchers to design and carry out robust studies. Implications for clinical practice, sponsors and regulators are highlighted.