Evaluating nicotine dependence levels in e-cigarette users Evaluación de los niveles de dependencia de la nicotina en usuarios de cigarrillos electrónicos

smokers, and even higher than observed levels in nicotine replacement therapy users (Marsot & Simon, 2015). On the other hand, low levels of self-reported nicotine dependence when vaping and a greater number of minutes between waking up and first use have been found among vapers, thereby accounting for lower nicotine dependence levels among this former group when compared to tobacco cigarette smokers (Foulds et al., 2015). This study aimed to explore nicotine dependence levels in a sample of experienced e-cigarette users (n=39; males=77%) and to compare them with current tobacco cigarette smokers (n=42; males=57%). Among e-cigarette users 20.5% were using second generation devices, while 79.5% were using third generation ones. We conducted several face-to-face interviews in order to assess sociodemographic and dependence related characteristics in both e-cigarette users and in smokers. Adapted versions of both the Fagerström test for nicotine dependence (FTND; Heatherton, Kozlowski, Frecker, & Fagerstrom, 1991) and the nicotine dependence syndrome scale (NDSS; Shiffman, Waters, & Hickcox, 2004) were used to analyze nicotine dependence in each of the groups. Biochemical markers of carbon monoxide and urinary cotinine analysis were also collected. Our findings extend previous research on e-cigarette use and nicotine addiction. Two main findings can be drawn from this work: (1) e-cigarette users were dependent on e-liquids containing nicotine, (2) e-cigarette users were found to be less niElectronic cigarettes (e-cigarettes) are non-combustible electronic nicotine delivery systems (ENDS) that mimic the experience of smoking tobacco (Harrell, Simmons, Correa, Padhya, & Brandon, 2014). They consist of three main elements: a rechargeable battery, an atomizer, and a tank. Since the e-cigarette entered the market in 2003, its prominence and use has greatly increased worldwide (Martínez-Sánchez et al., 2014). Recent data on e-cigarette prevalence in both European and American samples indicates that nearly 6.8% of adults are e-cigarette users to date (McMillen, Gottlieb, Shaefer, Winickoff, & Klein, 2015). Nevertheless, this growing popularity has raised several public health issues regarding its safety and effectiveness as an alternative for smoking cessation (Yu et al., 2016). Research focused on e-cigarettes and smoking cessation has provided mixed results. While several internet surveys and uncontrolled designs suggest e-cigarettes may be effective in promoting tobacco abstinence, others have not found such results. To date, recommendations of the World Health Organization points out that the effectiveness of e-cigarettes as a method for quitting is limited and requires more research (World Health Organization, 2014). A further concern involves abuse liability in current e-cigarette users (Cobb, Hendricks, & Eissenberg, 2015). Recent evidence has shown that nicotine levels as measured through plasma and saliva are similar to those seen in