Assessment
DISEASE
All participants in the 2 groups were asked to attend face-to-face follow-up visits with research staff (H.L., Y.L., H.Z., Z.Z., and X.Z.) at 1 month, 3 months, and 6 months after randomization. The primary outcome was the biochemically verified 6-month sustained abstinence rate, defined as the self-report of no smoking of any cigarettes after the designated quit date, which was validated biochemically by an expired air carbon monoxide level of less than 6 ppm at each follow-up point.Secondary outcomes were biochemically verified sustained abstinence rates at 1 month, 3 months, 1 to 3 months, and 3 to 6 months after randomization; biochemically verified 24-hour point prevalence of abstinence at each follow-up point; self-reported sustained abstinence rate; 24-hour point prevalence of abstinence at each follow-up point; change in nicotine dependence measured by the Fagerström Test for Nicotine DependenceAll face-to-face follow-up visits, which included administration of all biochemical verification tests and questionnaires, were conducted by staff members of the local Disease Control and Prevention Center and Peking University. Most of the meetings took place in rooms at the Disease Control and Prevention Center, but some staff members met participants in their homes or any place convenient for the participants.