Another cohort was made up of participants in randomized trials of smoking cessation interventions recruited in Madison and Milwaukee, Wisconsin (N = 398, WI). A final cohort was drawn from the Lung Health Study (N = 1943, LHS), a multi-site longitudinal study of COPD sponsored by the Division of Lung Disease of the National Heart, Lung and Blood Institute [38]. All ex-smokers were in the UT cohort and responded to smoking related assessments based upon their prior smoking patterns [39]. Participants began daily smoking at a mean age of 17.3 (SD = 4.1), smoked a mean of 28.3 cigarettes per day (CPD, SD = 13.9), smoked for a mean 30.7 years (SD = 9.5), and had a mean FTND score of 5.7 (SD = 2.2). Consistent with a history of chronic, heavy smoking, most subjects in the UT and LHS cohorts (N = 2302, 81% of the total sample) had mild to moderate chronic obstructive pulmonary disease (COPD) as determined by pulmonary function testing; lung function testing was not performed on the WI subjects.
