Diagnostic testing options available to emergency physicians continue to expand. The conflicts over the use and cost of testing have spilled over into the popular press and have generated questions from the radiologists who provide many of the interpretations of the images ordered in the emergency department.¹ Managing expensive diagnostic testing in the ED is one element of the value that emergency physicians bring to the American health system. It is important that all ED physician leaders understand the data on imaging rates to adequately address resource utilization queries and better manage their departments.

The ED has a critical and growing role as the diagnostic center for the medical community. This role is particularly important for patients who are being evaluated for potential admission to the hospital due to an acute-onset injury or illness. Because 68 percent of inpatients are processed through the ED, emergency physicians are responsible for a disproportionate share of diagnostic testing and the patient-flow issues related to it.

Diagnostic testing has changed markedly over the last 20 years, with the advent of imaging technology using a broad range of modalities (ultrasound, ionizing radiation, magnetic resonance, positron emissions, etc.). These remarkable tools provide unprecedented ability to evaluate patients as they present with a wide range of clinical problems.

There are two sources of data related to the utilization of diagnostic imaging in the ED over the last decades. The Centers for Disease Control and Prevention (CDC) gathers and reports data through the National Hospital Ambulatory Medical Care Survey (NHAMCS). NHAMCS data from the CDC are available from 1992 through 2011, the last available year. The Emergency Department Benchmarking Alliance (EDBA) uses a voluntary data submission process from a large number of EDs and has collected and reported on data through 2013.

The NHAMCS data survey measures the percent of patients who receive an imaging study, not taking into account how many imaging procedures are done on any single patient. The NHAMCS report found that 44 percent of patients received a simple X-ray in 1992. In 2011, that number was only 34 percent. The NHAMCS report indicates that 2 percent of patients had CT scanning performed in 1992. This increased to 14 percent in 2007 and peaked at 16 percent for 2010 and 2011.

The EDBA reports on ED utilization of diagnostic imaging as measured in the number of procedures performed per 100 patients seen. A patient having multiple imaging procedures performed (eg, a hip X-ray and a chest X-ray) would have two procedures in the EDBA reporting system but only be credited as one imaging patient in the NHAMCS data. The EDBA data survey for 2013 was developed from the performance measures reported by 1,151 EDs that saw 45 million patients in that calendar year.² The data are reported in cohorts based on type and volume of patients seen in the ED (see Table 1).