Does cigarette reduction while using nicotine replacement therapy prior to a quit attempt predict abstinence following quit date?

Background and Aims: Previous studies have reported that people who use a smoking cessation medication while smoking and reduce cigarette consumption spontaneously are three times more likely to stop smoking after a quit date. The aim was to replicate this and assess whether it arises because of willed effortful reduction rather than unwilled reduced drive to smoke caused by medication. Design: Secondary analysis of a trial where participants were randomised to smoke as normal or reduce by 75% over 2 weeks prior to quit date, using nicotine replacement therapy (NRT) in both arms. Setting: Thirty-one UK primary care practices. Participants: A total of 517 adult smokers seeking quitting support in the carbon monoxide (CO) analyses and 421 in the cigarettes/day analyses. Measurements: Russell Standard abstinence was recorded 4 weeks after quit date. The randomized groups were combined and the association between reduction and abstinence examined. The second analysis assessed whether this association differed by whether smokers were, or were not, instructed to reduce. Findings: In all participants, there was no evidence that reducing cigarettes/day or CO by at least half compared with not reducing predicted abstinence at 4 weeks [risk ratio (RR) = 0.88; 95% confidence interval (CI) = 0.68–1.14 and RR = 1.20; 95% CI = 1.00–1.44, respectively]. However, in smokers instructed to reduce, CO reduction was associated with 4-week abstinence (RR = 1.52; 95% CI = 1.16–2.00), but not among people advised not to reduce (RR = 0.91; 95% CI = 0.67–1.24). Conclusions: Smoking reduction prior to a target quit date while on a smoking cessation medication may only predict subsequent abstinence when smokers are consciously attempting to reduce.