Advanced diagnostic imaging use is increasing, raising concerns about patient safety and cost.1 Recent estimates indicate that 4000 future cancers may result from the head computed tomographic (CT) examinations performed nationwide in 20072 and that costs of CT and magnetic resonance imaging (MRI) doubled between 1997 and 2006.3 In US emergency departments (EDs), the greatest increase has been in neuroimaging (head CT and MRI).4 Nevertheless, there are no national benchmarks against which health care providers and hospitals can measure their use of ED neuroimaging. We aimed to calculate head CT and MRI use in US EDs and to examine patient and hospital factors associated with use.
We performed a cross-sectional analysis of neuroimaging in US EDs by analyzing the 2007 National Hospital Ambulatory Medical Care Survey (NHAMCS) ED component with a primary outcome of head CT use and a secondary outcome of head MRI use. We coded patient and hospital covariates a priori to identify predictors of neuroimaging and calculated the percentage of visits (with 95% confidence intervals [CIs]) associated with neuroimaging. We conducted multivariate logistic regression to estimate the adjusted association of covariates on the primary outcome. The regression model had good fit, with a C statistic of 0.71. Among visits in which head CT was performed, we calculated the leading reasons for visit5 and discharge diagnoses by grouping primary International Classification of Diseases, Ninth Revision, Clinical Modification discharge diagnoses into the 285 clinical categories of the Clinical Classification System.6 We performed all statistical analyses using SAS 9.1.3 (SAS Institute Inc, Cary, North Carolina).
There were approximately 117 million visits to 4891 US EDs in 2007, based on 35 490 ED visits in the NHAMCS sample. Head CT scans were performed during 6.7% (95% CI, 6.1%-7.3%) of visits, while head MRIs were performed during 0.26% (95% CI, 0.18%-0.35%) of visits. Patient and hospital characteristics associated with neuroimaging are presented in the Table. Patient characteristics independently associated with lower use of head CT use were decreasing age and non-Hispanic black race and ethnicity (vs non-Hispanic whites). Hospital characteristics associated with lower CT use included rural setting (vs urban) and hospitals owned by state or local governments (vs nonprofit hospitals).
The 3 leading reasons for visits among patients receiving head CTs in the ED were trauma (18.1%; 95% CI, 12.8%-23.5%), headache (13.0%; 95% CI, 10.8%-15.2%), and dizziness (6.1%, 95% CI, 4.6%-7.6%). The 3 leading discharge diagnosis categories were trauma (20.5%; 95% CI, 15.8%-25.3%), headache (9.2%; 95% CI, 7.4%-11.0%), and epilepsy/convulsions (5.2%; 95% CI, 3.8%-6.6%).
To our knowledge, this study provides the first nationally representative benchmarks of ED neuroimaging. In 2007, 1 in 14 ED patients received head CT, while 1 in 400 underwent head MRI. Increasing age was the strongest predictor of head CT use. While 1 in 34 children younger than 18 years received head CT, 1 in 7 patients 65 and older received one. Current guidelines addressing the use of ED head CT for trauma7 and acute headache8 exclude these older patients. Organizations interested in measuring and reducing neuroimaging will be challenged to define acceptable evidence-based appropriateness standards for older adults.
Use of head CT varied by race: 1 in 14 non-Hispanic white patients received head CT, compared with 1 in 19 non-Hispanic black patients. Yet it remains unclear whether this difference represents a quality disparity (ie, underuse) or an overuse disparity because the optimal rate of imaging is unknown and we could not assess appropriateness.
Large numbers of US ED patients are undergoing high-cost neuroimaging and receiving ionizing radiation with known cancer risks. Further research on appropriate indications for neuroimaging and implementation of performance improvement programs are needed to ensure that these valuable technologies are used in a safe and cost-effective manner.
Correspondence: Dr Raja, Department of Emergency Medicine, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115 (firstname.lastname@example.org).
Author Contributions:Study concept and design: Raja, Zane, Khorasani, and Schuur. Acquisition of data: Raja and Schuur. Analysis and interpretation of data: Raja, Andruchow, and Schuur. Drafting of the manuscript: Raja, Andruchow, and Zane. Critical revision of the manuscript for important intellectual content: Raja, Andruchow, Zane, Khorasani, and Schuur. Statistical analysis: Raja and Schuur. Administrative, technical, and material support: Raja, Zane, and Khorasani. Study supervision: Khorasani and Schuur.
Financial Disclosure: None reported.
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Association With Material Stature
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