Health policy/original researchEmergency Department Computed Tomography Utilization in the United States and Canada
Introduction
Recent studies have demonstrated substantial increases in medical computed tomography (CT) utilization in the United Kingdom,1 Canada,2 the United States, and worldwide.3 Imaging is already common in the emergency department (ED),4 and, each year in the 1990s and early 2000s, utilization increased.5, 6 A recent study of US ED imaging found a near 5-fold increase in scans from 1995 to 2007.7
Guidelines suggest that imaging is a useful diagnostic tool for many acute conditions,8, 9, 10 and it is reasonable for utilization to increase as new indications for testing are developed. However, as medical CT becomes more common, there is concern about the magnitude of imaging-related financial costs and radiation-induced malignancies.11 Concern is especially apt for the pediatric population, which is more susceptible to the effects of ionizing radiation than the adult population.12
The objective of this study was to compare ED CT rates in the United States and Ontario by visit characteristics and reason for visit subgroups. We hypothesized that overall CT utilization would be higher in the United States and increasing faster, and that visits involving high-risk cases of abdominal pain would have similar utilization of CT imaging in both jurisdictions.
Section snippets
Study Design, Setting, and Selection of Participants
This was a retrospective study of ED visits from 2003 through 2008, using a national probability-based survey in the United States and universal administrative health databases in Ontario. We chose these North American jurisdictions because they both house large ethnically diverse populations, and the populations access ED care with near-identical rates per capita13; however, differences in the demographics of the 2 populations are significant. Many of these differences will be discussed in the
Results
All US results are estimates that were generated by weighting complex survey data, whereas all Ontario results are “hard” numbers obtained from administrative databases. Also, results in both jurisdictions are unadjusted for differences in population characteristics.
Limitations
Our 2 data sets are significantly different: US results are national estimates derived from surveys at selected facilities around the nation, whereas Ontario data are “hard” numbers that are extracted from administrative sources at all Ontario hospitals. We were not able to examine patient-level outcomes in the United States, so cross-jurisdictional outcomes could not be compared. Furthermore, we did not use multivariate regression analysis to adjust for potential confounders because this would
Discussion
From 2003 to 2008, CT utilization increased for ED visits in both jurisdictions; and in 2008, 14.6% of all US visits involved CT compared with 7.3% in Ontario. Increases in CT utilization occurred across every subgroup in both jurisdictions, with one important exception: the proportion of visits involving CT for children younger than 10 years decreased. Meanwhile, the proportion for children younger than 10 years in the United States trended toward increase.
For nearly all reason for visit
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Please see page 487 for the Editor's Capsule Summary of this article.
Supervising editor: Ellen J. Weber, MD
Author contributions: CTB, MJV, and MJS conceptualized and designed the study and analyzed and interpreted the data. CTB and MJV acquired the data. CTB drafted the article, and all authors critically revised it for important intellectual content. CTB performed statistical analysis, with administrative and technical support from MTV. MJS supervised the study. CTB takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Dr. Berdahl is supported by the James G. Hirsch Endowed Medical Student Research Fellowship at the Yale University School of Medicine, and Dr. Schull is supported by the Canadian Health Services Research Foundation and the Commonwealth Fund as a 2010-11 Harkness Fellow.
Publication date: Available online May 14, 2013.