Emergency departments have appropriately developed a role as the diagnostic and treatment center of excellence (and availability) in the health system. Diagnostic testing has changed over the years but still consists mostly of obtaining and analyzing blood, urine, and other body fluids; obtaining tracings of electrical activity in the body; and obtaining images of the body using a broad range of modalities (ionizing radiation, magnetic resonance, positron emissions, and ultrasound). These sophisticated tools provide unprecedented evaluation of patients presenting with a wide array of illness and injury.

There is significant interest in the use of diagnostic testing, particularly imaging, in the emergency department. Quality measures are being developed that compare the use of diagnostic procedures among different emergency departments and among individual practitioners. It is necessary to have historical comparatives and trend data on the use of diagnostics to prepare for the use of new metrics as quality indicators. It is also necessary to understand the difference in utilization among emergency departments that serve different patient populations.

The Emergency Department Benchmarking Alliance (EDBA) uses a voluntary data submission process for a large number of emergency departments and has collected and reported on data through the year 2016. Definitions for the various performance measures are uniform.¹ The EDBA measures ED utilization of diagnostic testing in the number of procedures performed per 100 patients seen. The latest survey is compiling data from approximately 1,400 emergency departments that saw 55 million patients in 2016 and reports in cohorts based on type and volume of patients seen in the emergency department (see Table 1). The data would be considered “macro data” in measuring the performance of the entire large set of emergency departments and not for individual emergency physician performance.

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Table 1 shows differences in utilization of diagnostic testing based on volume served and patient population that is predominantly served in the emergency department. There are very significant increases in use of diagnostic testing in adult-serving emergency departments when compared to those serving pediatric populations. Pediatric emergency departments only use CT imaging about four times per 100 patients seen. Plain diagnostic X-rays show little difference in utilization based on volume. Volume over 40,000 patients per year also results in more frequent use of testing, including 12-lead ECGs.

Table 2 displays the trend data for 11 years of comparison. There is a trend to increasing utilization of ECGs, ultrasound, and MRI imaging. MRI utilization across all emergency departments has now reached about 1.6 procedures per 100 patients seen, but this increases to 2.0 in trauma centers. The reporting of MRIs has only occurred over the last five years, and the reporting of ultrasound has only occurred over the last four years, with each showing expanding use. The 11-year trend shows a decrease in the use of simple X-rays and a slight reduction in the use of CT imaging.