Transition from first illicit drug use to first injection drug use among rural Appalachian drug users: A cross-sectional comparison and retrospective survival analysis

Aim The study's objectives were to characterize initiation of injection drug use, examine the independent association of specific substance use with injection drug use and determine factors associated with rates of transition from first illicit drug use to first injection among a sample of rural Appalachian drug users. Design Interview-administered questionnaires were administered to a sample of drug users recruited via respondent-driven sampling. Setting Appalachian Kentucky. Participants Injection drug users (IDUs) (n=394) and non-IDUs (n=109). Measurements Data were collected on substance use and years from age at initiation of illicit substance use to 'event' (initiation of injection or date of baseline interview for non-IDUs). Logistic regression and Cox regression were used to identify factors associated with life-time injection drug use and transition time to injection, respectively. Findings OxyContin ^® was involved in nearly as many initiations to injection (48%), as were stimulants, other prescription opioids and heroin combined; for participants who initiated with OxyContin ^®, the median time from which they began OxyContin ^® use to their first injection of OxyContin ^® was 3 years. Adjusting for demographics, five prescription drugs (benzodiazepines, illicit methadone, oxycodone, OxyContin ^® and other opiates) were associated with an increased hazard for transitioning from first illicit drug use to first injection drug use (each at P<0.01). Conclusions In Appalachia, in the United States, the prescription opioid OxyContin ^® is widely used non-medically and appears to show a particularly high risk of rapid transition to injection compared with the use of other illicit drugs.