Description and nomenclature of 'outpatient' in medicine: A scoping review.

Abstract

<h4>Background</h4>The term "outpatient" refers to a patient attending hospital without overnight admission. Despite its importance in health service delivery, the term seems to be used inconsistently in the literature, hindering analysis and comparability.<h4>Objective</h4>To describe the use of outpatient in scientific and grey literature, identify patterns of incorrect usage, and propose an exploratory nomenclature.<h4>Methods</h4>We conducted a scoping review of scientific (Medline, 1952-2025) and grey literature (>2019). Eligible references included the term "outpatient" or described outpatient pathways within a hospital. The primary outcome was correct use of the formal definition. Multivariable regression explored patterns of incorrect use. A qualitative analysis informed the development of a proposed nomenclature.<h4>Results</h4>Of 1624 scientific references, 984 were included; incorrect use occurred in 47%, as misuse, non-use, or mixed-use. Pattern of incorrect use were observed in relation to articles published before 2013, and without manual tags/MeSH terms. Grey literature showed similar patterns across countries and institutions. Inductive analysis yielded a four-category nomenclature: unscheduled, scheduled, coordinated, and supervised.<h4>Conclusion</h4>This study highlights the widespread incorrect use of the term "outpatient" across countries, journals, and institutions. Greater conceptual clarity and the use of a shared nomenclature may support more reliable descriptions of hospital activity, improve cross-country comparability, and inform evidence-based health policy analysis.