Results
Of the planned 300 participants, a total of 188 participants (mean [SD] age, 49.1 [12.5] years; 102 [54%] female) were enrolled before the trial was stopped because of the COVID-19 pandemic. A total of 127 participants chose to use varenicline, including 64 randomized to adaptive treatment and 63 randomized to standard treatment, and 61 participants chose to use nicotine patches, including 31 randomized to adaptive treatment and 30 randomized to standard treatment. At baseline, participants smoked a mean (SD) of 15.4 (7.3) cigarettes per day. At 12 weeks after the target quit day, biochemically verified 30-day continuous smoking abstinence was observed in 23 of 95 participants (24%) in the adaptive treatment group and 8 of 93 participants (9%) in the standard treatment (odds ratio [OR], 3.38; 95% CI, 1.43-7.99; 