Trajectory modeling of cannabis use over 30 years identifies five unique longitudinal patterns

Cannabis is the most prevalently used psychoactive substance in the United States. Cannabis has conflicting federal and state legal status in the US, however medical and recreational cannabis use are increasing. When assessing health outcomes, cannabis use classification has been modeled largely as current use status (never/former/current) or cumulative use (joint-years). These methods do not describe longitudinal patterns of use which may have unique relationships with health outcomes. We used cannabis use data spanning 30 years from the Coronary Artery Risk Development in Young Adults Cohort (CARDIA) to create trajectories of current cannabis use during young and middle adulthood. We identified 5 unique patterns of the probability of cannabis use during young and middle adulthood in the CARDIA Cohort. To support the cannabis probability trajectories, we qualitatively examined cumulative cannabis use as joint-years for each trajectory group. Trajectory group 5 had high probability of consistent cannabis use (0.8-0.9% probability of use) and had the highest number of joint-years (0.6 +/- 0.4). Trajectory group 1 who had a lower probability of cannabis use (0.05-0% probability of use) with the lowest number of joint-years (0.1 +/- 0.1).