Introduction: Electronic cigarettes (e-cigarettes) have the potential to significantly reduce exposure to harmful constituents associated with cigarette smoking when smokers completely substitute cigarettes with e-cigarettes. This study examined patterns of e-cigarette and cigarette use, and extent of toxicant exposure, if smokers were instructed and incentivized to completely switch to e-cigarettes compared to instructions to use the product ad libitum. Aims and Methods: US adult daily smokers (n = 264; 49.2% female; Mage = 47.0), uninterested in quitting smoking immediately, were recruited from Minneapolis, MN, Columbus, OH, and Buffalo, NY. Participants were randomized to 8 weeks of instructions for (1) ad libitum use of e-cigarettes (AD-E), (2) complete substitution of cigarettes with e-cigarettes (CS-E), (3) complete substitution of cigarettes with nicotine gum or lozenge (CS-NRT), or (4) continue smoking of usual brand cigarettes (UB). Participants were incentivized for protocol compliance, including complete switching in the CS-E and CS-NRT groups. Outcome variables were cigarette smoking rate and tobacco-related biomarkers of exposure. Results: Smokers in the CS-E and CS-NRT groups showed lower rates of smoking and lower exposure to carbon monoxide, tobacco carcinogens, and other toxicants than smokers in the AD-E group. In general, no significant differences were observed between CS-E versus CS-NRT or between AD-E versus UB for most biomarkers. Significantly higher 7-day point prevalence smoke-free rates were observed for CS-E versus CS-NRT. Conclusions: Smokers instructed and incentivized to completely switch to e-cigarettes resulted in lower smoking rates and greater reductions in exposures to harmful chemicals than smokers instructed to use the product ad libitum. Implications: Smokers instructed to completely substitute e-cigarettes for cigarettes displayed significantly lower levels of smoking and biomarkers of exposure to carcinogens and toxicants, compared to smokers instructed to use e-cigarettes ad libitum and similar levels as smokers instructed to completely substitute with nicotine replacement therapies. Furthermore, a higher rate of complete switching was achieved with e-cigarettes versus nicotine replacement therapies. Approaches to maximize complete substitution with e-cigarettes are an important area for future research.
Bibliographical noteFunding Information:
The research reported in this publication was supported by grants U19CA157345 from the National Cancer Institute (DKH/PS), UL1 TR000062 and UL1 TR002494 from the National Center for Advancing Translational Science of the National Institutes of Health, and T32 DA007097 from the National Institute of Drug Abuse (EM). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.
© 2019 The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved.