Age and Small Airway Imaging Abnormalities in Subjects with and without Airflow Obstruction in SPIROMICS

• Published in: American journal of respiratory and critical care medicine Vol. 195; no. 4; pp. 464 - 472
• Main Authors: Martinez, Carlos H., Diaz, Alejandro A., Meldrum, Catherine, Curtis, Jeffrey L., Cooper, Christopher B., Pirozzi, Cheryl, Kanner, Richard E., Paine, Robert, Woodruff, Prescott G., Bleecker, Eugene R., Hansel, Nadia N., Barr, R. Graham, Marchetti, Nathaniel, Criner, Gerard J., Kazerooni, Ella A., Hoffman, Eric A., Ross, Brian D., Galban, Craig J., Cigolle, Christine T., Martinez, Fernando J., Han, MeiLan K.
• Format: Journal Article
• Language: English
• Published: United States American Thoracic Society 15.02.2017
• Subjects: Adult; Aged; Aged, 80 and over; Aging - pathology; Aging - physiology; Airway Obstruction - diagnostic imaging; Airway Obstruction - pathology; Airway Obstruction - physiopathology; Cohort Studies; Cross-Sectional Studies; Female; Forced Expiratory Volume - physiology; Humans; Lung - diagnostic imaging; Lung - pathology; Lung - physiopathology; Male; Middle Aged; Multicenter Studies as Topic; Multivariate Analysis; Original; Pulmonary Emphysema - diagnostic imaging; Pulmonary Emphysema - pathology; Pulmonary Emphysema - physiopathology; Smoking - adverse effects; Smoking - pathology; Spirometry; Tomography, X-Ray Computed; Vital Capacity - physiology; geriatrics; imaging analysis; lung function; spirometry; aging
• ISSN: 1073-449X; 1535-4970; 1535-4970
• DOI: 10.1164/rccm.201604-0871OC

Aging is associated with reduced FEV to FVC ratio (FEV /FVC), hyperinflation, and alveolar enlargement, but little is known about how age affects small airways. To determine if chest computed tomography (CT)-assessed functional small airway would increase with age, even among asymptomatic individuals. We used parametric response mapping analysis of paired inspiratory/expiratory CTs to identify functional small airway abnormality (PRM ) and emphysema (PRM ) in the SPIROMICS (Subpopulations and Intermediate Outcome Measures in COPD Study) cohort. Using adjusted linear regression models, we analyzed associations between PRM and age in subjects with or without airflow obstruction. We subdivided participants with normal spirometry based on respiratory-related impairment (6-minute-walk distance <350 m, modified Medical Research Council ≥2, chronic bronchitis, St. George's Respiratory Questionnaire >25, respiratory events requiring treatment [antibiotics and/or steroids or hospitalization] in the year before enrollment). Among 580 never- and ever-smokers without obstruction or respiratory impairment, PRM increased 2.7% per decade, ranging from 3.6% (ages 40-50 yr) to 12.7% (ages 70-80 yr). PRM increased nonsignificantly (0.1% [ages 40-50 yr] to 0.4% [ages 70-80 yr]; P = 0.34). Associations were similar among nonobstructed individuals with respiratory-related impairment. Increasing PRM in subjects without airflow obstruction was associated with increased FVC (P = 0.004) but unchanged FEV (P = 0.94), yielding lower FEV /FVC ratios (P < 0.001). Although emphysema was also significantly associated with lower FEV /FVC (P = 0.04), its contribution relative to PRM in those without airflow obstruction was limited by its low burden. In never- and ever-smokers without airflow obstruction, aging is associated with increased FVC and CT-defined functional small airway abnormality regardless of respiratory symptoms.