Emphysema predicts hospitalisation and incident airflow obstruction among older smokers: a prospective cohort study.
BACKGROUND
Emphysema on CT is common in older smokers. We hypothesised that emphysema on CT predicts acute episodes of care for chronic lower respiratory disease among older smokers.


METHODS
Participants in a lung cancer screening study age ≥ 60 years were recruited into a prospective cohort study in 2001-02. Two radiologists independently visually assessed the severity of emphysema as absent, mild, moderate or severe. Percent emphysema was defined as the proportion of voxels ≤ -910 Hounsfield Units. Participants completed a median of 5 visits over a median of 6 years of follow-up. The primary outcome was hospitalization, emergency room or urgent office visit for chronic lower respiratory disease. Spirometry was performed following ATS/ERS guidelines. Airflow obstruction was defined as FEV1/FVC ratio <0.70 and FEV1<80% predicted.


RESULTS
Of 521 participants, 4% had moderate or severe emphysema, which was associated with acute episodes of care (rate ratio 1.89; 95% CI: 1.01-3.52) adjusting for age, sex and race/ethnicity, as was percent emphysema, with similar associations for hospitalisation. Emphysema on visual assessment also predicted incident airflow obstruction (HR 5.14; 95% CI 2.19-21.1).


CONCLUSIONS
Visually assessed emphysema and percent emphysema on CT predicted acute episodes of care for chronic lower respiratory disease, with the former predicting incident airflow obstruction among older smokers.
Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom; Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
David A
DA
McAllister
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
Firas S
FS
Ahmed
Department of Radiology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
John H M
JH
Austin
Department of Radiology, Mount Sinai Medical Center, New York, New York, United States of America.
Claudia I
CI
Henschke
Department of Biomedical Engineering, University of Pennsylvania, Philadelphia, United States of America.
Brad M
BM
Keller
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
Adina
A
Lemeshow
School of Electrical and Computer Engineering, College of Engineering, Cornell University, Ithaca, New York, United States of America.
Anthony P
AP
Reeves
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
Sonia
S
Mesia-Vela
Department of Radiology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
G D N
GD
Pearson
Department of Radiology, New York University Langone Medical Center, New York, New York, United States of America.
Maria C
MC
Shiau
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America.
Joseph E
JE
Schwartz
Department of Radiology, Mount Sinai Medical Center, New York, New York, United States of America.
David F
DF
Yankelevitz
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, United States of America.
R Graham
RG
Barr
D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D000402:Airway Obstruction / Q000175:diagnosis* / Q000209:etiology; D055088:Early Detection of Cancer; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000209:etiology; D011656:Pulmonary Emphysema / Q000150:complications*; D012129:Respiratory Function Tests; D012907:Smoking / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity