Introduction Given the rapid increase in e-cigarette use, it is important to understand factors that may contribute to their initiation and maintenance. Because gender differences in tobacco use, product preferences, and expectancies are well established, similar gender differences may exist with e-cigarettes. The aim of this study was to identify gender differences among e-cigarette users in patterns of use, reasons for initiation and maintenance, and outcome expectancies regarding e-cigarettes. Methods Participants (N = 1815) completed an online survey from August through November, 2013. We assessed sociodemographics, smoking and e-cigarette history and use, and expectancies about e-cigarettes. Results We found gender differences in type of e-cigarette used, flavors used, nicotine dosage, source of information about e-cigarettes, place of purchase, and use of e-cigarettes where smoking is prohibited. In addition, males were more likely to report initiating e-cigarette use to quit smoking due to health concerns, whereas females were more likely to report initiation based on recommendations from family and friends. Males reported higher attributions for maintenance of e-cigarette use related to positive reinforcement (enjoyment), whereas females reported higher negative reinforcement attributions (stress reduction or mood management). Males reported more positive expectancies about e-cigarettes, including taste, social facilitation, and energy, whereas women rated e-cigarettes higher for weight control. Males also reported greater addiction-related e-cigarette expectancy than females. Conclusions Many of the gender differences with e-cigarettes parallel those previously found with traditional cigarette smoking. Although effect sizes associated with these differences were small, the results may help advance research and intervention development with respect to e-cigarette initiation, maintenance and cessation.

Background and aims Many smokers who have tried electronic cigarettes (“e-cigarettes”) continue to smoke, perhaps influenced by their beliefs about the outcomes of using e-cigarettes (“e-cigarette expectancies”). The primary aims of this study were to compare expectancies of dual users to former smokers, and to examine the association between expectancies and intentions to quit or reduce “vaping” among former smokers. Design and Setting A large cross-sectional online survey of e-cigarette users conducted in the USA. Participants We surveyed current e-cigarette users (N=1815), including both current cigarette smokers (“dual users,” n=381) and former smokers (n=1434). We further subdivided former smokers into those with (n=686) and without (n=748) intentions to reduce or quit e-cigarette use. Measurements The primary outcomes were self-reported past-month smoking status and, among former smokers, current intentions to reduce or quit e-cigarette use, both adjusted for potential confounders. E-cigarette expectancy items were primarily derived from a previously validated measure of smoking expectancies. Findings Dual users reported less positive expectancies than former smokers about e-cigarettes, rating e-cigarettes as more physically irritating (β=−0.10, p<0.001) and addictive (β=0.06, p=0.016), as well as less satisfying (β= −0.11, p<0.001). Former smokers with intentions to quit e-cigarettes also rated e-cigarettes less positively than former smokers without intentions to quit e-cigarettes, rating them more likely to damage health (β=0.16, p<0.001) and cause addiction (β=0.10, p<0.001), but less likely to taste good (β= −0.08, p=0.006). Conclusions Positive e-cigarette expectancies among e-cigarette users are associated with a greater likelihood of having quit smoking, but lower likelihood of intention to quit e-cigarette use.

Background The emergence of the electronic nicotine delivery systems (ENDS, or “e-cigarettes”) has resulted in nicotine and tobacco scientists committing increased resources to studying these products. Despite this surge of research on various topics related to e-cigarettes, it is important to characterize the evolving e-cigarette research landscape as a way to identify important future research directions. The purpose of this review was to broadly categorize published scholarly work on e-cigarettes using a structured, multi-level coding scheme. Methods A systematic literature search was conducted to collect articles on e-cigarettes that were published in peer-reviewed journals from 2006 through 2014. Studies were classified through 3 coding waves. Articles were first divided into research reports, literature reviews and opinions/editorials. Research reports were further categorized to determine the proportion of these studies using human participants. Finally, human studies were classified based on their methodologies: descriptive, predictive, explanatory, and intervention. Results Research reports (n = 224) and opinions/editorials (n = 248) were published at similar rates during this time period. All types of articles showed exponential rates of increase in more recent years. 76.3% of human research studies tended to be descriptive in nature, with very little research employing experimental (6.8%) or intervention-based methodologies (5.4%). Conclusions This review reinforces the idea that e-cigarettes are a disruptive technology exerting substantial influence on nicotine and tobacco science. This review also suggests that opinions on e-cigarettes may be outpacing our scientific understanding of these devices. Our findings highlight the need for more e-cigarette research involving experimental, intervention, and longitudinal designs.