Descriptions of the study populations are provided in the Supplementary Appendix, available with the full text of this article at NEJM.org. Because of the age distribution in the contemporary cohorts, analyses were restricted to participants who attained an age of 55 years or older during follow-up. CPS I analyses were based on 183,060 men and 335,922 women, enrolled in 1959 and followed through September 31, 1965. CPS II analyses are based on 293,592 men and 452,893 women enrolled in 1982 and followed through December 31, 1988. The five contemporary cohort studies representing the most recent period (2000– 2010) included the National Institutes of Health– American Association of Retired Persons Diet and Health Study (NIH–AARP),18 the ACS CPS II Nutrition Cohort19 (a subset of the original CPS II mortality study), the Women’s Health Initiative (WHI),20,21 the Nurses’ Health Study (NHS),22 and the Health Professionals Follow-up Study (HPFS) (Table S1 in the Supplementary Appendix).23 These are among the largest U.S. cohort studies that collected updated smoking information at least once during the period from 2000 through 2010.
