UCSF

INTRODUCTION: Using multiple tobacco and cannabis products is common among young adults and raises concerns about addiction and health risks. Few studies address daily use patterns of multiple products on the same day. We used daily diaries to identify patterns of substance use and associated factors among young adults who reported vaping nicotine and cannabis. METHODS: We collected smartphone-based daily diaries from 113 California young adults (mean age=23.8) who vaped nicotine or cannabis for 20 +  days in the past month. For 30 consecutive days, participants reported their daily use of nicotine/tobacco, cannabis, alcohol, craving for nicotine and cannabis vaping, and mood. We used multilevel latent class analysis to identify daily substance use patterns and mixed-effects logistic regression to identify factors associated with these patterns, controlling for baseline covariates (e.g., demographics, nicotine/cannabis dependence). RESULTS: Three latent classes emerged: Class 1 - "Nicotine vaping days" (52.7 % of the assessments), Class 2 - "Nicotine and cannabis co-vaping days" (39.9 %), and Class 3 -"Combustible tobacco and cannabis use days" (7.4 %). Higher levels of feeling sad on a given day were associated with increased likelihood of that day belonging to Class 1 (adjusted OR = 1.11, 95%CI95 %CI = 1.01 - 1.23). Higher cravings for cannabis vaping on a given day were associated with increased likelihood of that day belonging to Class 2 (adjusted OR = 1.81, 95 % CI = 1.63 - 2.01). CONCLUSION: Interventions should be tailored to varying daily substance use patterns among young adults who vape. Efforts targeting vaping cessation may also address combustible product use.