According to national surveys conducted from 2001 to 2008, ED crowding appears to be getting worse despite ongoing calls for action. During the study period, ED visit numbers grew 1.9% per year. The average occupancy increased 3.1% per year. While advanced imaging increased 140.0% during the 8 years, the following had large effects on occupancy trends:

Use of intravenous fluids and blood tests.
Performance of any clinical procedure.
Mention of two or more medications.

Medicare payer status and patients between the ages of 45 and 64 accounted for small disproportionate increases in occupancy.

Abstract: Annals of Emergency Medicine, June 22, 2012.