National study of emergency department observation services.

OBJECTIVES: The objective was to describe patient and facility characteristics of emergency department (ED) observation services in the United States.

METHODS: The authors analyzed the 2007 National Hospital Ambulatory Medical Care Survey (NHAMCS). Characteristics of EDs with observation units (OUs) were compared to those without, and patients with a disposition of ED observation were compared to those with a "short-stay" (<48 hour) hospital admission. Results are descriptive and without formal statistical comparisons for this observational analysis.

RESULTS: An estimated 1,746 U.S. EDs (36%) reported having OUs, of which 56% are administratively managed by ED staff. Fifty-two percent of hospitals with ED-managed OUs are in an urban location, and 89% report ED boarding, compared to 29 and 65% of those that do not have an OU. The admission rate is 38% at those with ED-managed OUs and 15% at those without OUs. Of the 15.1% of all ED patients who are kept in the hospital following an ED visit, one-quarter are kept for either a short-stay admission (1.8%) or an ED observation admission (2.1%). Most (82%) ED observation patients were discharged from the ED. ED observation patients were similar to short-stay admission patients in terms of age (median = 52 years for both, interquartile range = 36 to 70 years), self-pay (12% vs. 10%), ambulance arrival (37% vs. 36%), urgent/emergent triage acuity (77% vs. 74%), use of ≥1 ED medication (64% vs.76%), and the most common primary chief complaints and primary diagnoses.

CONCLUSIONS: Over one-third of U.S. EDs have an OU. Short-stay admission patients have similar characteristics as ED observation patients and may represent an opportunity for the growth of OUs.