Some characteristics of early-onset injection drug users prior to and at the time of their first injection.

Aims: This paper examines differences between early- and late-onset injection drug users (12-16 years versus 17-24 years) in terms of the antecedents and circumstances of first injection.

Design: Cross-sectional retrospective design, using logistic regression. Setting Australia: Sydney, Brisbane, rural New South Wales.

Participants: A total of 336 injection drug users aged 16-25 years at the time of interview.

Measurements: Independent variables included family injection drug use, homelessness and other demographic variables, drugs used prior to the first injection, length of pre-injection drug career, behaviours at time of first injection (e.g. drug injected, reasons/motives for the first injection, risk behaviours).

Findings: Early-onset injection was associated independently with: having a family who injected drugs, having left school early, an unreliable source of income, a short pre-injection drug career, planning of the first injection, reliance on others for administration of the first injection and denial that experimentation was the motive for the first injection. In bivariate analysis, early-onset injection was associated further with: homelessness, being an Indigenous Australian, omission of use of certain pre-injection drugs, group presence at first injection, reliance on others for acquisition of the first needle and syringe and having injected the first time because an injection was offered.

Conclusions: The research shows that early-onset, compared with late-onset injectors, are more likely to have an immediate family who inject drugs and other problematic beginnings in early life. They have an accelerated transition to injection, and differences in autonomy and motivation at first injection. These characteristics may make them more vulnerable to risk taking.