High Discordance of Chest X-ray and CT for Detection of Pulmonary Opacities in ED Patients: Implications for Diagnosing Pneumonia

Objective—To evaluate the diagnostic performance of chest x-ray (CXR) compared to computed tomography (CT) for detection of pulmonary opacities in adult emergency department (ED) patients. Methods—We conducted an observational cross sectional study of adult patients presenting to 12 EDs in the United States from July 1, 2003 through November 30, 2006 who underwent both CXR and chest CT for routine clinical care. CXRs and CT scans performed on the same patient were matched. CXRs and CT scans were interpreted by attending radiologists and classified as containing pulmonary opacities if the final radiologist report noted opacity, infiltrate, consolidation, pneumonia, or bronchopneumonia. Using CT as a criterion standard, the diagnostic test characteristics of CXR to detect pulmonary opacities were calculated. Results—The study cohort included 3,423 patients. Shortness of breath, chest pain and cough were the most common complaints, with 96.1% of subjects reporting at least one of these symptoms. Pulmonary opacities were visualized on 309 (9.0%) CXRs and 191 (5.6 %) CT scans. CXR test characteristics for detection of pulmonary opacities included: sensitivity 43.5% (95% CI: 36.4%–50.8%); specificity 93.0% (95% CI: 92.1%–93.9%); positive predictive value 26.9% (95% CI: 22.1%–32.2%); and negative predictive value 96.5% (95% CI: 95.8%–97.1%). Conclusion—In this multicenter cohort of adult ED patients with acute cardiopulmonary symptoms, CXR demonstrated poor sensitivity and positive predictive value for detecting pulmonary opacities. Reliance on CXR to identify pneumonia may lead to significant rates of misdiagnosis. © 2012 Elsevier Inc. All rights reserved. Corresponding Author: Wesley H. Self, MD MPH, Department of Emergency Medicine, Vanderbilt University School of Medicine, 1313 21st Ave South, 703 Oxford House, Nashville, TN 37232-4700, [email protected]. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author Manuscript Am J Emerg Med. Author manuscript; available in PMC 2014 February 01. Published in final edited form as: Am J Emerg Med. 2013 February ; 31(2): 401–405. doi:10.1016/j.ajem.2012.08.041. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript