Characteristics of frequent users of the emergency department in the general adult population: A systematic review of international healthcare systems

Highlights • Small proportion of frequent emergency department users account for high healthcare costs. • We performed a systematic review of the published literature characterizing frequent users. • Twenty cohort studies characterizing frequent users in 5 healthcare systems were identified. • Similar demographic, clinical and resource use characteristics were observed across systems. • International knowledge translation may help development of interventions and health policies.