Measures of crowding in the emergency department: a systematic review.

Objectives: Despite consensus regarding the conceptual foundation of crowding, and increasing research on factors and outcomes associated with crowding, there is no criterion standard measure of crowding. The objective was to conduct a systematic review of crowding measures and compare them in conceptual foundation and validity.

Methods: This was a systematic, comprehensive review of four medical and health care citation databases to identify studies related to crowding in the emergency department (ED).