The Relation Between Number of Smoking Friends and Adult Smoking Cessation Outcomes
Hitchman, Sara Christine
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Background: It is a basic principle of life that behaviour is guided by the social context. It matters to us whether significant others share with us the same likes and dislikes, and when they do not, that discrepancy is a source of potential for change in our individual beliefs, attitudes, and ultimately our behaviour. It is the importance of the social context that is the foundation for the research presented in this dissertation, which focuses on the relation between friends' smoking behaviour and individual smoking behaviour. Objectives: The objectives of this dissertation are to: (1) examine whether smokers report a greater number of smoking friends than chance would predict, (2) examine whether smokers’ number of smoking friends and changes in their number of smoking friends over time are related to demographic characteristics and variables that predict smoking cessation outcomes, (3) examine whether smokers’ number of smoking friends and changes in their number of smoking friends over time are related to smoking cessation outcomes, and (4) examine whether any relation between changes in number of smoking friends over time and smoking cessation outcomes is explained by changes in smokers’ social and subjective norms towards smoking. Respondents: Data were drawn from the International Tobacco Control Policy Evaluation Project Four Country Survey, a random-digit dial parallel prospective longitudinal cohort survey of nationally representative samples of adult smokers in Australia, Canada, the United Kingdom, and the United States. Samples included a Wave 1 cross-sectional sample (N=8,812), and a Wave 1-Wave 2 longitudinal sample (N=6,321). Methods: Number of smoking friends was measured by asking smokers how many of their five closest friends smoke. Change in number of smoking friends over time was the difference between smokers’ number of smoking friends at Wave 1 and Wave 2. Smoking cessation outcomes tested included: (1) intentions to quit at Wave 1 and Wave 2, (2) quit attempts between Wave 1 and Wave 2, (3) abstinence for at least one month at Wave 2 among everyone, and (4) abstinence for at least one month at Wave 2 among smokers who attempted to quit (successful quit attempts). Changes in respondents’ subjective and social norms towards smoking between Wave 1 and Wave 2 were also measured. Results: Smokers reported a significantly higher number of smoking friends than would have been expected by chance at Wave 1. There were also significant differences in smokers’ number of smoking friends. Notably, smokers who were male, younger, had low education, and lower incomes had more smoking friends. These groups were also more likely gain and less likely to lose smoking friends over time. Smokers with characteristics that made them unlikely to quit smoking, i.e., higher nicotine dependence, also had more smoking friends. Smokers with fewer smoking friends at Wave 1 were more likely to intend to quit at Wave 1 and more likely to succeed in their attempts to quit. Smokers who lost smoking friends over time compared to smokers who experienced no change in their number of smoking friends were more likely to intend to quit at Wave 2, attempt to quit, be abstinent at Wave 2, and succeed in their attempts to quit. There was some evidence that change in subjective norms partially mediated the relation between changes in number of smoking friends and attempts to quit. Conclusions: These findings suggest that the majority of smokers live in social contexts where smoking is heavily concentrated, and that there are demographic differences in smokers’ number of smoking friends and changes in their number of smoking friends over time. Overall, changes in number of smoking friends over time was a more significant and consistent predictor of smoking cessation outcomes than number of smoking friends at Wave 1. This finding agrees with theories of behaviour change that suggest that changes in the context are important when predicting behavioural change. Future studies of the predictors of quitting should consider how factors that change over time are related to quitting, particularly the number of people who smoke in smokers’ social contexts. Smoking cessation interventions should consider the challenges faced by smokers who live in contexts where smoking is heavily concentrated when attempting to quit. These challenges may include a higher number of smoking friends, difficulties avoiding smokers during their quit attempts, and making social contacts with non-smokers to support their desired non-smoking status.