Background There is a dearth of literature available that examines the characteristics of frequent users of urgent and emergency healthcare. Most research and literature explores this population by focusing within one clinical service rather than throughout the whole urgent and emergency healthcare system in England.

The aim was to examine how frequent users of: Out of Hours General Practitioners; NHS 111; Ambulance Services; and Emergency Departments are defined, what thresholds are used to categorise and what approaches are used to manage this population.

Method A systemic mapping exercise was undertaken to capture a wide range of data to gain a comprehensive understanding of how these services are currently working with regard to frequent users.

The search provided 5094 articles which were screened against the inclusion criteria leaving 156 articles to be analysed. Data was extracted and thematic synthesis created four main themes: typology with regard to definitions assigned; threshold variance; separation of the main population into subgroups; and case management approaches.

Results The systematic mapping exercise revealed that diverse definitions and thresholds were being employed by all services. The language used to describe these individuals was often negative and subjective. A single definition of High Intensity User (HIUs) has been selected and advocated for the standardisation within all services. This transposable terminology and identification process will aid in supporting and managing patients within all these services.

A taxonomy of HIUs has been developed from this research to sub-divide the main heterogeneous group into the 5 main classification groups. This meets a gap in current knowledge.

Conclusions The standardised identification process and taxonomy will facilitate interoperability and clarity between clinicians thus benefitting patient and their outcome. The support and management of HIUs will be more comparable between all urgent and emergency services and within the research community.