Abstract
Most clinical trials use 6 months or 1 year follow-ups as proxies for life-time smoking cessation. Retrospective studies have estimated 2-15% of smokers relapse each year after the first year of abstinence, but these have methodological problems such as memory bias. We searched for prospective studies of adult quitters that reported the number of participants abstinent at 1 yr follow-up and who remained abstinent at >or=2 year follow-ups. We included studies that reported the percent which remained lapse-free, did not continue treatment after 1 year, and had