Longitudinal patterns of cannabis and tobacco co-administration and concurrent use among young adult college students

Introduction: Co-use, including concurrent use or co-administration, of cannabis and tobacco is most prevalent in young adulthood and associated with worse health outcomes than use of either substance alone. This study examined latent classes of tobacco and cannabis concurrent use and co-administration, and transitions between classes from 2016 to 2019, among a sample of young adult college students in Texas. Methods: Participants included 4,448 young adults (64.2% female, 64.7% non-white, mean age = 20.5) in a longitudinal cohort study. Measures included past 30-day use of cigarettes. hookah, cigars, ENDS, cannabis, and cannabis and tobacco co-administration. Latent Markov models were used to estimate latent class membership and transitions between classes from 2016 to 2017 and 2017 to 2019. Results: Four latent classes emerged: non-use (58% of students) characterized by low/no probability of any use; general use (19%) characterized by some level of use of all behaviors; blunt and cannabis use class (13%) characterized by high probabilities of cannabis use and co-administration with blunts; and concurrent and co administration use (10%) with high probabilities of cigarette, cannabis, blunt, and spliff use. Most students remained in the same latent class from 2016 to 2019. Conclusions: While most students reported low/no tobacco and cannabis co-use, those who used cannabis and/or tobacco remained in their use classes over the course of the study (2016 to 2019). Public health advocates on college campuses should consider prevention and cessation programs that incorporate the constellation of behaviors related to cannabis and tobacco co-use and educate students about the health consequences of co-use.