Men and women may have differential susceptibility
to tobacco smoke. Women develop more severe COPD at
younger ages than men and with lower levels of cigarette
exposure.6 In the NETT (National Emphysema Treatment
Trial) study, women had fewer pack-years of cigarette
smoking than men, but had similarly severe COPD.7 A 2006
meta-analysis of smoking and COPD by Gan et al found
that female smokers had a faster annual decline in forced
expiratory volume in 1 second (FEV1) than male smokers.8
Moreover, Sørheim et al observed that among people with
COPD younger than age 60 years, women had a lower mean
FEV1 and more severe COPD with less cigarette-smoking
exposure.9 In that study, women had greater reductions in
FEV1 than men when they had fewer than 20 pack-years
of exposure, but after 25 pack-years of smoking, the dose–
response relationship of men and women was similar.