Intraindividual covariation between e-cigarette and combustible cigarette use in Korean American emerging adults

Critical gaps exist in understanding the patterns and correlates of dual use of electronic cigarettes (ECs) and combustible cigarettes (CCs), particularly in ethnic minority populations. In this study, we assessed CC and EC use in the naturalistic environment using ecological momentary assessment (EMA). We hypothesized that within-subject variation in EC use (yes/no each day) would be inversely associated with within-subject variation in number of CCs consumed and craving during that same day. We also examined gender and nicotine dependence as moderators of the EC-CC and EC-craving covariations. Korean American emerging adult (KAEA; 18-25 years old) smokers (N = 78) completed 7 days of EMA. Participants completed EMA surveys throughout the day, which assessed CC craving, and end-of-day surveys, which assessed EC use and the number of CCs smoked that day. Generalized linear mixed models were used to predict day-level EC use, with number of CCs smoked and craving during that same day, gender, and nicotine dependence as predictors (n = 501). We found that within-subject variation in CC use was not associated with same-day EC use; neither was within-subject variation in craving (ps > .27). Gender moderated the relationship between craving and EC use on a given day (p = .03); only for females, on the days with higher craving, the likelihood of their EC use that day was significantly heightened. This study does not suggest that EC use is linked with lower CC smoking quantity, at least at the day level and among KAEA smokers. CC craving may play a role in dual EC-CC use for KAEA female smokers.