Sex-specific features of emphysema among current and former smokers with COPD.

Recent studies suggest that males with chronic obstructive pulmonary disease (COPD) have more emphysema than females. It is not known if these differences persist across degrees of COPD severity. Our aim was to identify sex-specific differences in quantitative emphysema within COPD subgroups based on COPD severity. We included non-Hispanic white and African-American subjects from the COPDGene study with at least 10 pack-years of smoking and COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometry grade II or greater. We examined sex-specific differences in log-transformed emphysema (log per cent low-attenuation area (%LAA)) by GOLD spirometry grade among subjects with early-onset COPD (<55 years old) and advanced emphysema (>25% emphysema). Compared with females, males had higher log % LAA: overall (1.97 +/- 1.4 versus 1.69 +/- 1.6, beta=0.32 (0.04), p=1.34x10(-14)), and among non-Hispanic white (p=8.37x10(-14)) and African-American subjects (p=0.002). Females with early-onset COPD, severe emphysema and GOLD grade IV COPD had similar emphysema as males, but markedly fewer pack-years smoking (early-onset, p=0.01; severe emphysema and GOLD grade IV, p<0.001). This study identifies subsets of female smokers with COPD who are particularly susceptible to parenchymal destruction.