Study data published in JAMA Network Open described nicotine and cannabis vaping trajectories from adolescence to young adulthood in the United States. Polysubstance use was common, particularly among those with frequent nicotine vaping in adolescence or young adulthood.
This prospective cohort study administered surveys to students at 10 high schools in the Los Angeles metro area. Students were surveyed at 6-month intervals from the fall of 11th grade (2015) through the spring of 12th grade (2017). Participants were surveyed again approximately 1 to 2 years after completion of high school (2018-2019).
The surveys captured the past 30-day use of nicotine and cannabis by vaping. Age, highest parental educational level, gender, and race/ethnicity were also collected. Growth mixture modeling (GMM) was used to identify latent trajectories of vape use. Parallel GMM was used to assess co-occurrence of nicotine and cannabis vaping trajectories.
The study sample comprised 3322 participants. Mean age was 16.50 ± 0.42 years at baseline; 1777 (53.55%) were girls; and 47.4% were Hispanic or Latino. GMM identified a 5-trajectory model as the best fit for both nicotine and cannabis data: non-users (2246 [67.6%] for nicotine; 2157 [64.9%] for cannabis); infrequent users (566 [17.0%]; 608 [18.3%]); moderate users (167 [5.0%]; 233 [7.0%]); young adult-onset frequent users (213 [6.4%]; 190 [5.7%]); and adolescent-onset escalating frequent users (131 [3.9%]; 134 [4.0%]). Covariates were added to each model to identify predictors of certain trajectories.
For nicotine vaping, boys had higher odds of membership in the adolescent-onset escalating frequent use (odds ratio [OR], 2.88; 95% CI, 1.58-5.23; P =.01) and moderate use (OR, 1.98; 95% CI, 1.26-3.14; P =.003) trajectories compared to girls. Hispanic and Latino individuals were less likely to belong to the adolescent-onset escalating frequent use trajectory compared to non-Latino and non-Hispanic individuals (OR, 0.38; 95% CI, 0.17-0.82; P =.01).
For cannabis vaping trajectories, boys were more likely than girls to report adolescent-onset escalating frequent use over nonuse (OR, 1.95; 95% CI, 1.03-3.66; P =.05). Overall, polysubstance vaping was common. Participants with adolescent-onset escalating frequent use (85%) and young adult-onset frequent use (93%) of nicotine vaping frequently reported concurrent cannabis vaping.
In this study, trajectories of nicotine vaping use were comparable to those of cannabis vaping use. Those who reported more frequent nicotine vaping were more likely to also use cannabis. The primary study limitation was its use of self-report data to capture substance use; some participants may have underreported their vaping habits. However, no validated clinical instruments exist to capture vaping frequency.
“In this study…[a] significant proportion of individuals initiated and participated in both nicotine and cannabis vaping during young adulthood, suggesting that research is warranted to identify developmentally appropriate interventions,” the investigators wrote. “Further study of the substantial polysubstance vaping observed between nicotine and cannabis vaping trajectories [is also] needed to develop more effective regulatory practices and interventions.”
Lanza HI, Barrington-Trimis JL, McConnell R, et al. Trajectories of nicotine and cannabis vaping and polyuse from adolescence to young adulthood. JAMA Netw Open. 2020;3(10):e2019181. doi:10.1001/jamanetworkopen.2020.19181