Marijuana use trajectories among drug-using youth presenting to an urban emergency department: Violence and social influences

Aims: This paper examined longitudinal marijuana use trajectories among drug-using youth presenting to the ED to inform intervention development. Methods: Given interest in substance use and violence, this study oversampled those presenting with assault injuries. Assault-injured youth (ages 14-24) endorsing past 6-month drug use (n = 349), and a sex and age proportionally-sampled comparison group (n = 250) endorsing drug use, completed a baseline assessment and follow-ups at 6, 12, 18, and 24 months. Latent class trajectory analyses examined days of marijuana use over 2 years. Multinomial regression analyses examined baseline, 12-month and 24-month factors associated with substance use trajectory groups. Results: Trajectory analyses identified 5 groups: Low (Low; 28.2%: n=169); Intermittent (INT; 16.2%; n=97); Moderate Decline (MD; 12.0%; n=72); High decline (HD, 13.2%; n=79) and Chronic (C: 30.4%; n=182). At baseline, as compared to the Low group, the other trajectory groups were more likely to be male and have greater levels of physical aggression. At 12- and 24-months, negative and positive peer influences, incarceration and community violence were additional characteristics associated with the greater marijuana use trajectories (as compared to the Low group). Conclusions: Interventions for drug-using youth presenting to the urban ED should address peer influences, physical aggression and community violence exposure, given the association between these characteristics and greater marijuana use trajectories. (C) 2017 Elsevier B.V. All rights reserved.