Care in the emergency department: How crowded is overcrowded?

Objectives: To examine how emergency department (ED) overcrowding has been defined in the medical literature. Methods: Using the National Library of Medicine's PubMed and MEDLINE databases (1966 to 2002), a comprehensive review of the English-language medical literature was conducted to identify explicit criteria for defining ED overcrowding. Inclusion criteria were original articles, editorials, and reviews; news articles and letters to the editor were excluded. Using a standardized extraction form, publications were described as primary if the title or an objective statement in the introductory or methods paragraph referred to crowding or overcrowding; all other citations were categorized as secondary. Each report was then evaluated to determine whether crowding or over-crowding, was defined explicitly or implicitly. Explicit definitions included phrases such as "Crowding was defined as... " or "Overcrowding occurred when... "; other definitions were characterized as implicit. Results: A total of 231 candidate articles were identified; 91 met inclusion criteria, and 53 (58%) were primary articles about ED crowding or overcrowding. Among these primary articles, 23 (43%) had explicit definitions of crowding or overcrowding. The definitions varied widely in content and focus, including ED, hospital, or external (nonhospital) factors. Conclusions: Although ED overcrowding has been a topic of frequent investigation, current definitions of the problem are often implicit or focus on factors outside of the ED itself. A more consistent approach to defining ED overcrowding would help to clarify the distinctions between causes, characteristics, and outcomes of overcrowding.