We tabulated age-specific deaths, person-years at risk, and death rates according to smoking status in each of the contributing cohorts, pooling the data for the five contemporary cohorts. Death rates were standardized according to the U.S. age distribution in 2000. Cox proportional-hazards regression was used to calculate age-adjusted and multivariable-adjusted relative-risk estimates according to smoking status (former smokers and current smokers vs. those who never smoked), according to the intensity and duration of smoking among current smokers, and according to the age at the time of quitting among former smokers. Multivariable-adjusted analyses were stratified according to cohort and age at baseline (in 1959, 1982, or 2000) and were further adjusted according to race and educational level.
