New psychoactives within polydrug use trajectories-evidence from a mixed-method longitudinal study.

AIMS

To provide public health-related research evidence on types and usage patterns of new psychoactive substances (NPS), developmental pathways into NPS and decision-making factors for, and associated harms of, NPS use.

DESIGN

Three-phase mixed-methods design, including a latent class analysis (LCA) of the longitudinal Belfast Youth Development Study (BYDS), a narrative analysis of interviews with NPS users and a three-step approach manual method modelling using regressions to reveal classes of substance use and their associated predictors and outcomes.

SETTING

Northern Ireland.

PARTICIPANTS

A total of 2039 people who responded to the questions on 'ever use' of the drug variables included at wave 7 (aged 21 years) of the BYDS. Eighty-four narrative interviews with NPS users.

MEASUREMENTS

Categories of drug use identified by LCA. Predictors and outcomes included measures of family, partners, peers, substance use, school, delinquency and mental health.

FINDINGS

A four-class solution provided the best fit for the data: alcohol; alcohol and tobacco; alcohol, tobacco and cannabis; and polydrug (the latter including NPS). The qualitative analysis yielded a taxonomy that distinguished how NPS operate within a wider range of drug repertoires from experimental to problematic.

CONCLUSIONS

In Northern Ireland, new psychoactive substances appear to be a feature of broader polydrug use rather than a standalone class of drug use.