Association between e-cigarette and conventional cigarette use among Spanish adolescents.

In recent years, studies have highlighted the upward trend in electronic cigarette use among adolescents, as well as the potential of e-cigarette use to lead to subsequent conventional cigarette use. The study's aims were two-fold: 1) to examine the progression from e-cigarette use to conventional cigarette use; and 2) to analyze the differences in the severity of smoking pattern among dual users (i.e., e-cigarette and conventional cigarette use), cigarette-only smokers, and e-cigarette-only users in a Spanish adolescent population. Data were obtained from the ESTUDES, a representative survey of addictive behaviors of Spanish adolescents aged 14-18, which was comprised of 38,010 adolescents (Mage = 15.69; SD = 1.19; 51.35% females). Results indicate that lifetime e-cigarette use increased the prevalence of subsequent conventional cigarette use by 1.86 times (95% CI 1.74, 1.99), and the prevalence of conventional cigarette use in the last month by 2.38 times (95% CI 2.19, 2.58), independently of whether the e-cigarette contains nicotine or not. Dual users showed a higher percentage of daily smokers, and a greater number of cigarettes per day, a higher use of e-cigarettes with nicotine, and an earlier age of smoking onset. Regarding risk perception, e-cigarette-only users perceived both conventional tobacco and e-cigarettes as less harmful (all p-values < .001). These findings document the strength of association between e-cigarette and conventional cigarettes, and underscore the importance of developing legal restrictions and prevention strategies aimed at reducing e-cigarette use, which in turn would reduce tobacco use.