Polysubstance use trajectories and non-prescribed opioid use among young adults: a national longitudinal study

To identify longitudinal trajectories of cannabis, alcohol, and cigarette use from ages 18-24 and examine whether trajectory-group membership is associated with non-prescribed opioid use during young adulthood.

Data were drawn from restricted Monitoring the Future (MTF) panel data. Participants completed the base year survey and at least one of three follow-up surveys. Individuals reporting non-prescribed opioid use at baseline were excluded. The analytic sample included 62,223 participants from 42 US base year cohorts (1976-2018). Group-based trajectory modeling identified patterns of past-year cannabis, alcohol, and cigarette use. The outcome was any past-year non-prescribed opioid use reported at follow-up through ages 23/24. Weighted logistic regression models estimated associations between trajectory-group membership and non-prescribed opioid use, adjusting for background characteristics; sex-stratified models were also estimated.

Five trajectory groups emerged: (1) no cannabis and cigarette/low-to-moderate alcohol use (14.7%); (2) no cannabis and cigarette/high alcohol use (32.7%); (3) high use of all substances (21.2%); (4) low cannabis use/moderate-to-high cigarette use/high alcohol use (19.6%); and (5) high-to-moderate cannabis use/moderate-decreasing-to-low cigarette use/high alcohol use (11.8%). Compared with Group 1, all other groups had higher adjusted odds of non-prescribed opioid use (p-values <0.01). Patterns were generally similar by sex.

Compared with young adults characterized by no cannabis or cigarette use and low-to-moderate alcohol use, those in trajectory groups characterized by high use of one or more substances had higher odds of non-prescribed opioid use during young adulthood. Findings suggest that non-prescribed opioid use during young adulthood often occurs within a broader pattern of polysubstance use involving cannabis, alcohol, and cigarette use.