Emphysema on CT Without COPD Predicts Higher Mortality Risk

Diedtra Henderson

December 16, 2014

People whose lungs displayed signs of emphysema in computed tomography (CT) scans were at greater mortality risk, even those without airflow obstruction or without chronic obstructive pulmonary disease (COPD), according to a population-based study.

Elizabeth C. Oelsner, MD, MPH, from Columbia University in New York City, and colleagues report their findings in an article published in the December 16 issue of the Annals of Internal Medicine.

Some 29% of smokers undergoing lung cancer screening and 4% of healthy adults undergoing cardiac scanning are found to have emphysema, which destroys lung parenchyma and degrades intra-alveolar walls, according to the authors. Although emphysema can predict worse outcomes among patients with COPD, the research team sought to determine the prognostic importance of the lung condition among smokers and nonsmokers free of COPD.

The Multi-Ethnic Study of Atherosclerosis (MESA) enrolled 6814 participants aged 45 to 84 years from 2000 to 2002. The patients had a cardiac CT at baseline, and interviewers contacted either the patient or a family member every 9 to 12 months to check vital status. A total of 3847 participants with baseline measurements of endothelial function completed spirometry from 2004 to 2006. Of those, 2965 participants had no airflow obstruction.

"Emphysema-like lung assessed quantitatively on CT was associated with increased all-cause mortality among persons without airflow obstruction or COPD on spirometry in a large, population-based, multiethnic cohort," write Dr Oelsner and colleagues. "These findings suggest that 'subclinical' emphysema among patients without spirometrically defined COPD is clinically relevant."

Over a median of 6.2 years, 186 deaths occurred. After adjustment for potential confounders, including cardiovascular risk factors and forced expiratory volume in 1 second (FEV1), emphysema was independently associated with higher mortality (adjusted hazard ratio per one-half interquartile range, 1.14; 95% confidence interval, 1.04 - 1.24; P = .004).

The relationship between emphysema-like lung and all-cause mortality was consistent across age, race/ethnicity, and body mass index and was most pronounced among current smokers, the authors write. The damage to the lungs caused by emphysema results in less available area for gas exchange, which can reduce functional status and impair ability to exercise and may be associated with hypoxia, the authors write. Although there are no current therapies that specifically target emphysema, they should be investigated, the authors note.

"Associations were more consistent among smokers, but harmful associations among never-smokers could not be excluded. These findings suggest that emphysema confers excess risk independent of spirometrically defined COPD," Dr Oelsner and coauthors conclude.

Financial support for the study was provided by the National Heart, Lung, and Blood Institute. Three coauthors disclosed receiving grants from the National Institutes of Health, one of whom further disclosed receiving grants from Alpha1 Foundation, personal fees from UpToDate, and travel reimbursement from the COPD Foundation; another of whom further disclosed being a founder and shareholder in VIDA Diagnostics, a company that commercializes lung imaging analysis software, and being an unpaid member of the Siemens Medical Imaging CT advisory board; and third of whom further disclosed receiving consulting fees from Insmed, travel support from American College of Chest Physicians and American Thoracic Society, personal fees from the European Respiratory Journal, and grants from Actelion, Bayer, GeNO, Gilead, Ikaria, Lung Biotech, Merck, Pfizer, Pulmonary Hypertension Association, and United Therapeutics. One author disclosed being a consultant for Boehinger-Ingelheim, Gilead, Immuneworks, Intermune, and XVIVO therapeutics. An additional study author disclosed receiving grant support from Toshiba Medical Systems. The remaining authors have disclosed no relevant financial relationships.

Ann Intern Med. 2014;161:863-873. Abstract

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