Screening programs evaluated.

PY, pack-years; YSQ, years since quitting. Reference programs: no screening and an approximation of the National Lung Screening Trial design (at age 62, 3 annual screens for smokers with > = 30 PY, and < = 15 YSQ).
All screening programs simulated U.S. cohorts born in 1950. For individuals meeting the pack-year and (for former smokers) years since quitting cutoffs, the first screen occurs at the beginning age and last screen occurs at the ending age. Programs are labeled as follows: Frequency (Annual, Biennial, Triennial) Age Start-Age Stop-minimum PY- maximum YSQ. As an example, B55-85-20-15 corresponds to biennial screening starting at age 55, ending at age 85, subject to a minimum pack-year history of 20 and a maximum years since quitting (for former smokers) of 15.