Meeting today's healthcare needs: Medicine at the interface.

The demographic of Singapore has undergone dramatic change. Historically, younger patients with communicable diseases predominated, whereas patients are now older with chronic multimorbidity and functional impairment. This shift challenges existing health and social care systems in Singapore, which must pivot to meet the changing need. The consequences of mismatched health and social care to patient needs are the fragmentation of care, dysfunctional acute care utilisation and increasing care costs. In Singapore and internationally, there is an inexorable rise in acute care utilisation, with patients facing the greatest point of vulnerability at transitions between acute and chronic care. Recently, innovative care models have developed to work across the boundaries of traditional care interfaces. These "Interface Medicine" models aim to provide a comprehensive and integrated approach to meet the healthcare needs of today and optimise value with our finite resources. These models include Acute Medical Units, Ambulatory Emergency Care, Extensivist-Comprehensivist Care, Virtual Wards, Hospital-at-Home and Acute Frailty Units. We describe these models of care across the acute care chain and explore how they may apply to the Singapore setting. We discuss how these models have evolved, appraise the evidence for clinical effectiveness, point out gaps in knowledge for further study and make recommendations for future progress.