Use of Computed Tomography in Emergency Departments in the United States: A Decade of Coughs and Colds

Computed tomography (CT) can be an essential tool in guiding the management of acute or life-threatening pulmonary disease. Increasing use of CT, however, has raised concerns about the effects of ionizing radiation on organs within the radiation field, including the thyroid, lungs, and breast.¹ Beyond the risk posed by ionizing radiation, high resolution CT may have unintended downstream consequences related to incidental findings and overdiagnosis, leading to a costly and potentially harmful diagnostic, therapeutic, or interventional cascade.² Increasing use of CT is most concerning among patients with the least to gain (eg, patients with illnesses of low acuity or at low risk of serious pathological conditions) or the most to lose (eg, young patients in whom CT carries the greatest risk of causing future radiation-related cancers). We sought to examine trends in the use of CT, and in clinical decision-making, for patients presenting to the emergency department (ED) with respiratory symptoms.

Using data from 2001 to 2010 in the National Hospital Ambulatory Medical Care Survey (NHAMCS), an annual national survey that obtains information about patients, presenting symptoms, and management for a systematic sample of visits, we identified visits by adults 18 years of age and older who presented to the ED of a hospital in the United States with a primary respiratory symptom. Data analysis was conducted from November 2013 through February 2015. The complex sampling strategy and analytic design of the NHAMCS allow the derivation of nationally representative information about the use of ambulatory-care services. We stratified ED visits according to symptom location in the lower respiratory (eg, cough or shortness of breath) vs upper respiratory tract (eg, sore throat or nasal congestion) and acuity of illness based on triage rating and vital signs.

Our primary outcome variable was CT performed during an ED visit. Secondary outcomes included diagnosis and management strategies (antibiotic prescription and hospital admission). We present weighted crude point estimates (in 2-year intervals) and, using multiple logistic regression, time trends, both crude and adjusted for age, race, sex, region, and insurance status.

Dartmouth College’s institutional review board waived review of this research.

The 23 416 ED visits among adults with respiratory symptoms recorded in the NHAMCS between 2001 and 2010 represented an estimated 79 million ED sample visits in the United States. Overall use of CT imaging quadrupled during the 10-year period, from 2.2% (2001-2002) to 9.4% (2009-2010) (odds ratio, 4.6; 95% CI, 3.4-6.2) of visits. Use of CT increased at least 4-fold within each symptom group, increasing most steeply among patients with the least acute reason for imaging (ie, the lowest absolute CT rates), those with nonacute upper respiratory symptoms, among whom the use of CT increased from 0.5% to 3.6% (odds ratio, 7.4; 95% CI, 1.3-42.0) (Figure). Odds ratios cited represent crude likelihood in 2009-2010 vs 2001-2002. Adjusted odds ratios were comparable (Table).

The use of CT increased comparably across all age strata, including a 4-fold increase among the youngest patients (aged 18-39 years) (Table). Management (antibiotic prescription and hospital admission) did not appear to change, while the proportion of patients discharged without a diagnosis (ie, with a symptom-based diagnosis) increased during the study period.

Use of CT for the evaluation of respiratory symptoms in the EDs of hospitals in the United States has quadrupled during the past decade, and regardless of patients’ symptoms, acuity of illness, or age, this trend shows no signs of slowing.

Our study has several limitations related to lack of clinical data beyond those collected through the NHAMCS. First, we were unable to confirm the accuracy of the chief complaint of patients making the ED visits included in the study. Second, we could not ensure that the CTs done during the patients’ ED visits targeted the primary (respiratory) symptoms. Previous investigators have made comparable assumptions.³

Our study expands on the findings of prior investigators, showing overwhelming consistency of the escalating use of CT, including its use for patients with the least chance of benefit, and those with the greatest likelihood of harm. Costs and the risks of exposure to ionizing radiation aside, excessive use of CT is associated with a proliferation of incidental findings and overdiagnosis, each of which trigger downstream cascades of even more imaging, radiation, and intervention.² Although many factors have been implicated as drivers of the growth in use of CT, including fee-for-service incentive structures that can conflict with evidence-based decision making,⁴ solutions to such problems have been elusive. Recently, however, the American Board of Internal Medicine Foundation’s Choosing Wisely campaign⁵ and the American College of Radiology⁶ have addressed the harms of excessive medical imaging. Our findings further highlight the urgent need for developing and implementing strategies to promote more judicious use of CT. Efforts by policy makers and medical-center leaders to realign incentives that promote the escalating use of CT remain a societal imperative.

Corresponding Author: Frank S. Drescher, MD, Pulmonary and Critical Care Medicine, Veterans Affairs, 215 N Main St (111), White River Junction, VT 05009 (frank.drescher@va.gov).

Published Online: December 28, 2015. doi:10.1001/jamainternmed.2015.7098.

Author Contributions: Dr Drescher had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Both authors.

Acquisition, analysis, or interpretation of data: Both authors.

Drafting of the manuscript: Drescher.

Critical revision of the manuscript for important intellectual content: Sirovich.

Statistical analysis: Drescher.

Administrative, technical, or material support: Drescher.

Study supervision: Sirovich.

Conflict of Interest Disclosures: None reported.

Funding/Support: Dr Drescher was supported by a Veterans Integrated Service Network 1 (VA New England) Career Development Award.

Role of the Funder/Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The views expresed herein do not necessarily represent the views of the Department of Veterans Affairs or the US government.

Previous Presentation: This study was presented as a poster at the American Thoracic Society International Conference; May 19, 2014; San Diego, California.