High discordance of chest x-ray and computed tomography 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 3423 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%).


CONCLUSIONS
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.
Department of Emergency Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-4700, USA. wesley.self@vanderbilt.edu
Wesley H
WH
Self
D Mark
DM
Courtney
Candace D
CD
McNaughton
Richard G
RG
Wunderink
Jeffrey A
JA
Kline
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed