Educational level significantly modified the association of current and former smoking with some of the mortality end points in the contemporary cohorts (P = 0.05) (Table S14 in the Supplementary Appendix). In general, the estimated relative risks for current and former smokers with only a high-school education or less were similar to or larger than the estimates for current and former smokers who were college graduates. This was consistently true with respect to the relative risks of death from COPD and ischemic and other heart diseases for women and former smokers but not for male current smokers. The timing of information on smoking status also affected the association between current smoking and certain end points, but the changes were small; in most cases, analyses based on fully updated smoking information underestimated the associations when smoking status was documented at baseline or 2 years before death or the end of follow-up for women and men (Tables S15 and S16, respectively, in the Supplementary Appendix).
