COPD Risk Predicted by Large Airway Dimensions on Computed Tomography

According to the results of a study published in the Annals of the American Thoracic Society, greater Pi10 (10 mm luminal perimeter) was associated with accelerated lung function decline, incident spirometry-defined chronic obstructive pulmonary disease (COPD), and chronic lower respiratory disease (CLRD) hospitalization and mortality in a general population-based sample without clinical lung disease.

Large airway dimensions on computed tomography (CT) have been associated with lung function, symptoms, and exacerbations in COPD, as well as symptoms in smokers with preserved spirometry. However, their prognostic significance in individuals without lung disease has not been defined.

In the prospective MESA study, Elizabeth C. Oelsner, MD, from the Department of Medicine, Columbia University College of Physicians and Surgeons, New York City, and colleagues examined the relationship between large airway dimensions on CT and respiratory outcomes in a population-based cohort of adults without prevalent lung disease.

The investigators recruited participants aged 45 to 84 years without cardiovascular disease or prevalent CLRD from 2000 to 2002. Spirometry was measured between 2004 and 2006, and 2010 and 2012, and CLRD hospitalizations and deaths were classified by validated criteria through 2014. The investigators calculated Pi10 as the average wall thickness for a hypothetical airway of 10 mm lumen perimeter from measures of airway wall thickness and lumen diameter. Models were adjusted for age, sex, principal components of ancestry, body mass index, smoking status, pack-years, scanner, percent emphysema, genetic risk score, and initial forced expiratory volume in 1 second (FEV₁) percent predicted.

Greater Pi10 was associated with a 9% faster FEV₁ decline (95% CI, 2%-15%; P =.012) and increased incident COPD (odds ratio [OR], 2.22; 95% CI, 1.43-3.45; P =.0004) per standard deviation in 1830 participants. The researchers also found that over the course of 78,147 person-years, “higher Pi10 was associated with [a] 57% higher risk for first CLRD hospitalization or mortality (P =.0496) per standard deviation. Of Pi10’s component measures, both greater [airway wall thickness] and narrower lumen predicted incident COPD and CLRD clinical events.”

The authors noted that these findings were independent of initial lung function and add support to the literature that suggests that early changes in airway morphology predict risk for CLRD, and that Pi10 and other CT measures of large airway dimensions may aid in identifying and characterizing individuals at increased risk of developing CLRD, specifically COPD.

They noted that the limited number of events that occurred during this study raised concerns regarding statistical power and potential overadjustment, but also that the results were similar and statistically significant in both crude and sequentially adjusted analyses and were consistent with lung function results.

Reference

Oelsner EC, Smith BM, Hoffman EA, et al. Prognostic significance of large airway dimensions on computed tomography in the general population: the Multi-Ethnic study of Atherosclerosis (MESA) Lung Study [published online March 12, 2018]. Ann Am Thorac Soc. doi: 10.1513/AnnalsATS.201710-820OC