Age-varying associations between e-cigarette use and peer use, household use, and exposure to e-cigarette commercials among alternative high school students in Southern California

INTRODUCTION: Electronic cigarettes (e-cigarettes) have rapidly become the most commonly used tobacco product among youth in the United States. Exposure to advertising, peer use, and household use, increases the risk of current e-cigarette use; however, the influence of these factors may be dynamic across adolescence. The aim of this study is to examine the age-varying associations between e-cigarette use and peer use, household use, and exposure to e-cigarette commercials among alternative high school students in Southern California. METHODS: Using data previously collected for a tobacco marketing study, we examine the age-varying associations of current e-cigarette use and three risk factors (peer use, exposure to commercials, and household use) across ages 15 to 20 years using time-varying effect modeling (TVEM). Analyses include three waves of data from alternative high school students (N=1060 students; 2036 observations). RESULTS: The probability of e-cigarette use gradually increased over the age of 15 years and then decreased by the age of 17 years for females and after the age of 18 years for males. Significant gender differences were observed between the ages of 17 and 19.5 years. Peer e-cigarette use was associated with higher odds of current e-cigarette use across all ages for females and after the age of 16 years for males. Exposure to e-cigarette commercials increased current use significantly for males between the ages of 16 and 18 years. Household use increased the odds of current use of e-cigarettes between the ages of 17 and 19 years for males and under 16.5 and over 18 years for females. CONCLUSIONS: The findings highlight the utility of TVEM in understanding the risk factors of e-cigarette use and suggest that these factors are dynamic across adolescence.