A small fraction of individuals account for the bulk of population healthcare expenditures in the USA, Denmark and other industrialised countries.1–4 Although many high-cost patients show consecutive high-cost years, the majority experience a'cost bloom', or a surge in healthcare costs that propels them from a lower to the upper decile of population-level healthcare expenditures between consecutive years.4 Proactively identifying and managing care for high-cost patients--especially cost bloomers, who may disproportionately benefit from interventions to mitigate future high-cost years--can be an effective way to simultaneously improve quality and reduce population health costs.5–16 However, since the Centers for Medicare and Services (CMS) commissioned the Society of Actuaries to compare leading prediction tools more than 10 years ago, scant progress has been made in improving cost-prediction tools.17 Overcoming these and other challenges associated with the management and care of high-cost patients is essential to achieving a higher value healthcare system.