Abstract
AIMS: To examine whether polyuse of cigarettes and other smoked products (polysmoking) is predictive of quit attempts and quit success. DESIGN: A prospective multi-country cohort design. SETTING: Australia, Canada, England and the United States. PARTICIPANTS: A total of 3983 adult daily cigarette smokers were surveyed in 2016 (wave 1 of data collection) and were re-contacted in 2018 (wave 2) (i.e. waves 1-2 cohort) in the International Tobacco Control Four Country Smoking and Vaping (ITC 4CV) surveys; and 3736 smokers were surveyed in 2018 and re-contacted in 2020 (wave 3) (i.e. waves 2-3 cohort). MEASUREMENTS: Participants were asked about their cigarette smoking and use of cigars, cigarillos, pipes and waterpipes. Outcomes were quit attempts between two survey waves and success, defined as having quit smoking all the combustible tobacco at the subsequent survey for 1 month or more. FINDINGS: Levels of polysmoking were 12.7% in the waves 1-2 cohort and 10.5% for the waves 2-3 cohort. Compared with cigarette-only smokers, polysmokers were more likely to attempt to quit between waves 1 and 2 [54.9 versus 42.7%, adjusted odds ratio (aOR) = 1.37, 95% confidence interval (CI) = 1.08-1.74, P < 0.01], but not between waves 2 and 3 (43.8 versus 40.1%, aOR = 0.94, 95% CI = 0.72-1.22). Polysmoking predicted reduced likelihood of success in both cohorts among attempters and the overall samples. Between waves 2 and 3 there were significantly more transitions to non-daily smoking among the polysmokers (12.4 versus 5.3%, χ(2) = 40.4, P < 0.001). CONCLUSIONS: There is a consistent association between polysmoking (use of cigarettes together with other smoked products) and reduced quit success for combustible tobacco, but it is probably due to increased likelihood of transitioning to non-daily use rather than complete cessation.