E-cigarette, cigarette, and cannabis use

We assessed a number of days of e-cigarette, cigarette, and cannabis use in the past 30 days. We also assessed e-cigarette use characteristics, including how often participants typically use e-liquids with THC and how often they typically use e-liquids with nicotine salt (never, rarely, some of the time, most of the time, all of the time). Those who reported some, most, or all of the time were classified as typically using e-liquids with THC and nicotine salt, respectively. Participants indicated the type of e-cigarette device they use most often (disposable device, device with replaceable prefilled cartridges, device with a tank that refills with liquids, mod system) and the 3 flavors they use most often (tobacco, menthol, fruit/dessert, other).

E-cigarette cessation-related factors

Participants indicated the importance of quitting and their confidence in quitting e-cigarettes (0 = ‘not at all’ to 10 = ‘absolutely’). They also reported past 12-month e-cigarette quit attempts (i.e. number of times they stopped using e-cigarettes for ≥1 days because they were trying to quit; 0–31+) and readiness to quit e-cigarettes (i.e. seriously thinking about quitting: yes, within the next 30 days; yes, within the next 6 months; yes, in more than 6 months; not thinking about quitting).

E-cigarette cessation/reduction challenges

A list of 13 common challenges to e-cigarette cessation was developed based on the literature¹²; participants indicated whether they had ever experienced each when trying to quit or cut down e-cigarette use (e.g. ‘I struggled with withdrawal symptoms’, ‘People important to me made it a challenge to resist vaping’, ‘I told myself vaping doesn’t pose any real health risks’).

Impact of e-cigarette cessation messages on motivation and confidence

Participants were asked to indicate the impact of 5 distinct messages targeting motivation (e.g. ‘Did you know that over 60% of young adults like you want to quit vaping?’) and the impact of 8 distinct messages targeting confidence (e.g. ‘Remember that quitting is a process; be patient with yourself and proud of all your hard work’) on their quitting motivation and confidence, respectively (1 = ‘no impact at all’ to 7 = ‘a lot of impact’). For primary analyses, items were summarized as the average response for the perceived impact of messages targeting motivation (correlations >0.4, p<0.001; Cronbach’s alpha=0.85) and messages targeting confidence (correlations >0.4, p<0.001; Cronbach’s alpha=0.90), respectively.

Recommendations for quitting poly-use of e-cigarettes, cigarettes, and cannabis

Participants responded to 2 items asking: ‘How would you recommend that someone quit smoking cigarettes and vaping?’ (quit both at the same time; quit smoking cigarettes first, then quit vaping; quit vaping first, then quit smoking cigarettes) and ‘How would you recommend that someone quit smoking cigarettes and vaping and using marijuana?’ (quit all three at the same time; quit smoking cigarettes first, then quit using marijuana second, then quit vaping nicotine; quit using marijuana first, then quit smoking cigarettes second, then quit vaping nicotine; quit smoking cigarettes first, then quit vaping nicotine second, then quit using marijuana; quit vaping nicotine first, then quit smoking cigarettes, then quit using marijuana).

Sociodemographic characteristics

We coded participants’ MSA of residence and assessed their age, sex, race, ethnicity, and sexual orientation.