To explore the relationship between our top COPD-associated variants and imaging features of emphysema and airway thickness, we queried data from a GWAS of COPD quantitative imaging features77. For each genome-wide significant COPD susceptibility locus in our overall meta-analysis, we assessed the corresponding quantitative imaging GWAS effect size, effect direction, and P value for association with the following quantitative imaging traits: %LAA-950 (percentage low attenuation area, using a threshold of −950 Hounsfield units); Perc15 (value of Hounsfield units at the 15th percentile of the density histogram); Pi10 (airway wall area: the value for a hypothetical airway of 10 mm internal perimeter obtained by plotting a regression line of the square root of the airway wall area versus the airway internal perimeter); and WAP (percentage of the wall area compared to the total bronchial area).
