Patterns of use and biomarkers of exposure among ‘dual’ tobacco cigarette and electronic cigarette users in Canada.
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Background: Tobacco use remains the leading risk factor for preventable disease in Canada. Although tobacco smoke is the direct cause of smoking-induced diseases, nicotine addiction sustains the use of tobacco. Electronic cigarettes (e-cigarettes) are battery-powered devices that deliver nicotine in an aerosol form. Despite a restriction on the sale of nicotine-containing e-cigarettes in Canada, products with and without nicotine are accessible to Canadians. Although e-cigarettes are likely to be much less harmful than tobacco cigarettes, empirical evidence of potential reduced risk at the individual level is limited. To date, behavioural switching studies involving tobacco cigarettes and e-cigarettes are limited by restrictions placed on e-cigarette user and product characteristics, and few have examined biomarkers of exposure among concurrent (dual) users of these products. Furthermore, although dual users constitute the majority of e-cigarette users in Canada, little is known about their behaviour. The current study seeks to fill several critical evidence gaps regarding dual users’ patterns of use and exposure to nicotine and tobacco smoke constituents in the Canadian context. Objectives: The study examined: 1) Patterns of use and perceptions of tobacco cigarettes and e-cigarettes among dual users. In the context of product switching, the study examined: 2) Exposure to nicotine and compensatory behaviour; 3) Exposure to tobacco smoke constituents; 4) Symptoms of nicotine withdrawal for tobacco cigarettes and e-cigarettes, respectively; 5) Self-efficacy for abstaining from smoking tobacco cigarettes and using e-cigarettes, respectively; and 6) Perceived respiratory health. Methods: An un-blinded within-subjects experiment was conducted with a sample of adult daily dual users (n=48) in Kitchener-Waterloo and Toronto, Ontario. Participants completed three consecutive seven-day periods in which the use of tobacco cigarettes and e-cigarettes was experimentally manipulated, resulting in four study conditions: dual use, exclusive use of tobacco cigarettes, exclusive use of e-cigarettes, and use of neither product. To control for order effects, the order in which participants experienced the study conditions was randomized. Participants’ behaviours and exposure to nicotine and tobacco smoke constituents were assessed following each study condition. Patterns of use and product perceptions were examined at baseline using descriptive statistics. Repeated measures models were used to examine the following outcomes: compensatory behaviour for nicotine, exposure to tobacco smoke constituents, symptoms of nicotine withdrawal, self-efficacy, and perceived respiratory health. Results: Dual users were 36 years of age, mostly male (71%), and exhibited low to moderate nicotine dependence (FTCD: 4.7 (SD=1.9)). Study participants had smoked and vaped daily for 17.4 (SD=12.2) and 1.2 (SD=0.9) years, respectively, and all reported initiating use of tobacco cigarettes prior to e-cigarettes. Although dual users reported similar daily consumption of tobacco cigarettes and e-cigarettes (13.7 (SD=5.6) tobacco cigarettes per day vs. 10.9 (SD=11.4) bouts of e-cigarette use, p=0.09), a greater proportion reported smoking tobacco cigarettes within the first hour of waking (98% vs. 59% for e-cigarettes; p<0.001). Virtually all dual users reported using tank systems (92%) and e-cigarettes with nicotine (94%). The most commonly reported reasons for using e-cigarettes included: to smoke fewer tobacco cigarettes (79%), to help with cravings for tobacco cigarettes (71%), and because of the belief that e-cigarettes are less harmful than tobacco cigarettes (71%). Compared to tobacco cigarettes, dual users considered e-cigarettes as more socially acceptable (65%), less satisfying (67%), less pleasurable (64%), less harmful (87%), and less expensive (81%). Findings from the product-switching experiment indicated that compared to dual use, levels of urinary cotinine were stable when participants exclusively smoked (p=0.524), but significantly decreased when they exclusively vaped (p=0.027), despite significant increases in e-cigarette consumption (p=0.001). Biomarkers of exposure, including exhaled carbon monoxide (CO), urinary 1-hydroxypyrene (1-HOP), and urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), were significantly lower when participants exclusively vaped, as compared to when they engaged in dual use (CO: -41%, p<0.001; 1-HOP: -31%, p=0.025; NNAL: -30%, p=0.017). A similar trend was observed among participants abstaining from both tobacco cigarettes and e-cigarettes, as compared to dual use (CO: -26%, p<0.001; 1-HOP: -14% (ns); NNAL: -35%, p=0.016). In addition, biomarkers of exposure showed an increasing trend among participants when they exclusively smoked as compared to dual use (CO: +21%, p=0.029; 1-HOP: +23%, p=0.048; NNAL: +8% (ns)). Study participants experienced significantly greater urges to smoke tobacco cigarettes when they were not permitted to do so (p=0.001). Although changes in participants’ self-efficacy for abstaining from tobacco cigarettes depended on the order in which they experienced study conditions, the self-efficacy of all participants at the end of the product-switching experiment did not differ significantly from their baseline values. In contrast, participants reported no significant changes in urges to use e-cigarettes (p=0.460) or in their self-efficacy to abstain from using e-cigarettes (p=0.150) across study conditions. Dual users reported significant improvements in various domains of respiratory health when they abstained from smoking tobacco cigarettes, including improvement in experiencing shortness of breath, cough, cough with phlegm, sounds emanating from the chest, and in perceived lung function (p<0.001 for all). Conclusions: The findings suggest that dual use behaviour is similar to that in other jurisdictions, despite Canada’s restrictive regulatory framework for these products. Tobacco cigarettes appear superior to e-cigarettes in their ability to deliver nicotine. Although abstaining from smoking tobacco cigarettes elicits cravings, it is also associated with significant improvements in perceived respiratory health. Consistent with other research, results from the current study demonstrate that abstaining from tobacco cigarettes is the most important factor in reducing exposure to tobacco smoke constituents. Therefore, dual use is likely to have public health benefit only to the extent that it leads to complete smoking cessation.
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Christine Daria Czoli (2017). Patterns of use and biomarkers of exposure among ‘dual’ tobacco cigarette and electronic cigarette users in Canada.. UWSpace. http://hdl.handle.net/10012/12188