Identification of chronic obstructive pulmonary disease in lung cancer screening computed tomographic scans.
BACKGROUND
Smoking is a major risk factor for both cancer and chronic obstructive pulmonary disease (COPD). Computed tomography (CT)-based lung cancer screening may provide an opportunity to detect additional individuals with COPD at an early stage.


OBJECTIVE
To determine whether low-dose lung cancer screening CT scans can be used to identify participants with COPD.


METHODS
Single-center prospective cross-sectional study within an ongoing lung cancer screening trial. Prebronchodilator pulmonary function testing with inspiratory and expiratory CT on the same day was obtained from 1140 male participants between July 2007 and September 2008. Computed tomographic emphysema was defined as percentage of voxels less than -950 Hounsfield units (HU), and CT air trapping was defined as the expiratory:inspiratory ratio of mean lung density. Chronic obstructive pulmonary disease was defined as the ratio of forced expiratory volume in the first second to forced vital capacity (FEV(1)/FVC) of less than 70%. Logistic regression was used to develop a diagnostic prediction model for airflow limitation.


METHODS
Diagnostic accuracy of COPD diagnosis using pulmonary function tests as the reference standard.


RESULTS
Four hundred thirty-seven participants (38%) had COPD according to lung function testing. A diagnostic model with CT emphysema, CT air trapping, body mass index, pack-years, and smoking status corrected for overoptimism (internal validation) yielded an area under the receiver operating characteristic curve of 0.83 (95% CI, 0.81-0.86). Using the point of optimal accuracy, the model identified 274 participants with COPD with 85 false-positives, a sensitivity of 63% (95% CI, 58%-67%), specificity of 88% (95% CI, 85%-90%), positive predictive value of 76% (95% CI, 72%-81%); and negative predictive value of 79% (95% CI, 76%-82%). The diagnostic model showed an area under the receiver operating characteristic curve of 0.87 (95% CI, 0.86-0.88) for participants with symptoms and 0.78 (95% CI, 0.76-0.80) for those without symptoms.


CONCLUSIONS
Among men who are current and former heavy smokers, low-dose inspiratory and expiratory CT scans obtained for lung cancer screening can identify participants with COPD, with a sensitivity of 63% and a specificity of 88%.
Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, Postbus 85500, 3508GA Utrecht, The Netherlands. o.m.mets@umcutrecht.nl
Onno M
OM
Mets
Constantinus F M
CF
Buckens
Pieter
P
Zanen
Ivana
I
Isgum
Bram
B
van Ginneken
Mathias
M
Prokop
Hester A
HA
Gietema
Jan-Willem J
JW
Lammers
Rozemarijn
R
Vliegenthart
Matthijs
M
Oudkerk
Rob J
RJ
van Klaveren
Harry J
HJ
de Koning
Willem P Th M
WP
Mali
Pim A
PA
de Jong
D000368:Aged; D003430:Cross-Sectional Studies; D004646:Emphysema / Q000000981:diagnostic imaging; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000209:etiology; D011829:Radiation Dosage; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000379:methods*