OR14-1PATTERNS AND TRANSITIONS IN SUBSTANCE USE AMONG YOUNG SWISS MEN

Introduction. The stages of involvement in illicit drugs other than cannabis remain vague and few studies focused on the last steps of drug-use trajectories. This study investigated this topic. Methods. We used data from the Swiss Longitudinal Cohort Study on Substance Use Risk Factors (C-SURF) to assess exposure to drug use (alcohol, tobacco, 16 illicit drugs including heroin, and five prescription drugs including opioids) at two times point (N = 5,041). Patterns and trajectories of drug use were studied using latent transition analysis (LTA) and cross-lagged panel models. Results. The LTA identified five classes of drug users showing a pattern involving adding alcohol, tobacco, cannabis, middle-stage drugs (uppers, hallucinogens, inhaled drugs), and final-stage drugs (e.g. heroin, ketamine, crystal meth). The most common transition was to remain in the same latent class. Heroin use predicted later opioid use (b = .071, p = .003) but not the reverse (b = -.005, p = .950). Conclusion. The pattern of drug use displayed the well-known sequence of drug involvement (licit drugs/cannabis/other illicit drugs), but added a distinction between "middle-stage" and "final-stage" drugs. Progression along the whole drug course remained rare among participants in their twenties. For the final stage, heroin appeared as to be a step for opioid use