Aims: To identify prototypical developmental patterns of tobacco product and cannabis use and co-use initiation during adolescence, and determine risk factors for and consequences of these initiation patterns.
Design: Prospective repeated-measures cohort with eight semi-annual assessments during high school. Multiple-event process survival mixture modeling identified latent initiation classes with distinct patterns of variation in timing of use initiation of tobacco products and cannabis. We then estimated: (1) associations of baseline risk factors with membership in initiation classes and (2) differences between initiation classes in frequency of cannabis and tobacco product use at the final assessment.
Setting: Ten high schools in the Los Angeles, CA, USA metropolitan area, 2013-17.
Participants: Students [1031 (45.4%) males; mean (standard deviation) age at baseline = 14.6 (0.39) years] who had never used any tobacco products or cannabis at baseline 9th grade assessment (n = 2272).
Measurements: Self-report measures of electronic cigarette (e-cigarette), combustible cigarette, hookah, cigar/cigarillos and cannabis use were collected at each assessment.
Findings: Four distinct tobacco and cannabis use initiation classes were identified: (1) early and high-risk cannabis and polytobacco initiators (n = 116; 5.1%); (2) early cannabis and polytobacco initiators (n = 172; 7.6%); (3) late cannabis and e-cigarette initiators (n = 431; 19.0%); and (4) abstainers (n = 1553; 68.4%). At baseline, older age for the early and high-risk cannabis and polytobacco initiators [odds ratio (OR) = 1.22, 95% confidence interval (CI) = 1.10, 1.35, P < 0.001], peer cannabis use (OR = 1.60, 95% CI = 1.23, 2.08, P < 0.001) and delinquent behavior (OR = 1.30, 95% CI = 1.08, 1.55, P = 0.004) were associated with membership in the three initiation classes (versus abstainers). Membership in the early and high-risk cannabis and polytobacco initiators class (versus three other classes) was significantly associated with increased past 30-day frequency and daily intensity of use at the final assessment (P-values < 0.001).
Conclusions: Older age, peer cannabis use and delinquent behavior appear to be risk factors for the initiation of tobacco/cannabis product use among high school students in the Los Angeles metropolitan region. Early and higher-risk polyproduct use initiation appears to be associated with greater escalation of past 30-day and daily tobacco and cannabis use at the end of the high school.
Keywords: Adolescents; cannabis; cigarette; e-cigarette; initiation; substance use.
© 2020 Society for the Study of Addiction.