Quantitative CT metrics are associated with longitudinal lung function decline and future asthma exacerbations: results from SARP-3.

Abstract

BACKGROUND\nCurrently there is limited knowledge of what imaging assessments of asthma are associated with accelerated longitudinal lung function decline.\n\n\nOBJECTIVES\nWe aimed to assess whether quantitative computerized tomography (qCT) metrics are associated with longitudinal lung function decline and morbidity in asthma.\n\n\nMETHODS\nWe analyzed 205 qCT scans of adult asthma patients, and calculated baseline markers of airway remodeling, lung density, and pointwise regional change in lung volume (Jacobian measures) for each participant. Using multivariable regression models, we then assessed the association of qCT measurements with the outcomes of future lung function change, future exacerbation rate, and changes in validated measurements of morbidity.\n\n\nRESULTS\nGreater baseline wall area percent (WA%) (β=-0.15, 95% CI -0.26 to -0.05, P<0.01), hyperinflation% (β=-0.25, 95% CI -0.41 to -0.09, P<0.01), and Jacobian gradient measurements (cranial-caudal β=10.64, CI 3.79 to 17.49, P<0.01; posterior-anterior β=-9.14, CI -15.49 to -2.78, P<0.01) were associated with more severe future lung function decline. Additionally, greater WA% (rate ratio=1.06, CI 1.01 to 1.10, P=0.02), air-trapping% (rate ratio=1.01, CI 1.00 to 1.02, P=0.03), and lower Jacobian determinant mean (rate ratio=0.58, CI 0.41 to 0.82, P<0.01) and Jacobian determinant standard deviation (rate ratio=0.52, CI 0.32 to 0.85, P=0.01) were associated with a greater rate of future exacerbations. However, imaging metrics were not associated with clinically meaningful changes in scores on validated asthma morbidity questionnaires.\n\n\nCONCLUSIONS\nBaseline qCT measures of more severe airway remodeling, more small airways disease and hyperinflation, and less pointwise regional change in lung volumes were associated with future lung function decline and asthma exacerbations.