Cross-country comparison of smokers' reasons for thinking about quitting over time: findings from the International Tobacco Control Four Country Survey (ITC-4C), 2002-2015

Objective: To explore between-country differences and within-country trends over time in smokers' reasons for thinking about quitting and the relationship between reasons and making a quit attempt.

Methods: Participants were nationally representative samples of adult smokers from the UK (N=4717), Canada (N=4884), the USA (N=6703) and Australia (N=4482), surveyed as part of the International Tobacco Control Four Country Survey between 2002 and 2015. Generalised estimating equations were used to evaluate differences among countries in smokers' reasons for thinking about quitting and their association with making a quit attempt at follow-up wave.

Results: Smokers' concern for personal health was consistently the most frequently endorsed reason for thinking about quitting in each country and across waves, and was most strongly associated with making a quit attempt. UK smokers were less likely than their counterparts to endorse health concerns, but were more likely to endorse medication and quitline availability reasons. Canadian smokers endorsed the most reasons, and smokers in the USA and Australia increased in number of reasons endorsed over the course of the study period. Endorsement of health warnings, and perhaps price, appears to peak in the year or so after the change is introduced, whereas other responses were not immediately linked to policy changes.

Conclusions: Differences in reasons for thinking about quitting exist among smokers in countries with different histories of tobacco control policies. Health concern is consistently the most common reason for quitting and the strongest predictor of future attempts.