Outcomes in syncope research: a systematic review and critical appraisal

Syncope is the common clinical manifestation of different diseases, and this makes it difficult to define what outcomes should be considered in prognostic studies. The aim of this study is to critically analyze the outcomes considered in syncope studies through systematic review and expert consensus. We performed a systematic review of the literature to identify prospective studies enrolling consecutive patients presenting to the Emergency Department with syncope, with data on the characteristics and incidence of short-term outcomes. Then, the strengths and weaknesses of each outcome were discussed by international syncope experts to provide practical advice to improve future selection and assessment. 31 studies met our inclusion criteria. There is a high heterogeneity in both outcome choice and incidence between the included studies. The most commonly considered 7-day outcomes are mortality, dysrhythmias, myocardial infarction, stroke, and rehospitalisation. The most commonly considered 30-day outcomes are mortality, haemorrhage requiring blood transfusion, dysrhythmias, myocardial infarction, pacemaker or implantable defibrillator implantation, stroke, pulmonary embolism, and syncope relapse. We present a critical analysis of the pros and cons of the commonly considered outcomes, and provide possible solutions to improve their choice in ED syncope studies. We also support global initiatives to promote the standardization of patient management and data collection.