Predictors of Injection Drug Use Among Opioid-Using Young Adults: A Need for Interventions to Prevent Escalation of Opioid Use

Introduction: Young people who use opioids are at risk for transition to injection drug use (IDU) which can, in turn, significantly increase risk for health-related harms. This study aimed to identify demographic, behavioral and network-related factors associated with regular IDU among young adults who use POs nonmedically and/or heroin.

Methods: New York City young adults (n=464) were recruited via Respondent-Driven Sampling for a survey to assess their drug use trajectories and patterns, and were tested on-site for HCV antibodies. Eligible participants were ages 18-29 and had used POs nonmedically and/or heroin in the past 30 days. Bivariate analyses using ANOVA and chi-square tests were conducted to compare participants who reported regular IDU (3 or more times/week) in the past 12 months with participants who had never injected drugs.

Results: Overall, participants were 66% male and 72% white with a mean age of 24.5 years and a relatively high level of education (40% had attended some college). Although 60% were from middle-class or higher SES backgrounds, 28% were currently homeless. Most (77%) had initiated nonmedical PO use in their teens (at 16.7, on average), with 87% eventually progressing to regular PO use, 85% to regular heroin use and 64% to regular heroin injection. 64% of participants reported regular IDU in the past 12 months, while 28% had never injected drugs. Regular injectors were significantly older (M=25 y/o) than never-injectors (M=23.3 y/o) and were significantly more likely to be homeless (38% vs. 5%). Regular injectors were far more likely to be HCV+ (33% vs. 0%) and to report lifetime experience of overdose (59% vs. 23%). Compared to never-injectors, regular injectors reported more frequent use of heroin (M=21 vs. 11 days in the past 30) and POs (M=14 vs. 6 days in the past 30), and were significantly more likely to report using cocaine in the past 30 days (43% vs. 26%) and to have ever received drug treatment (87% vs. 47%). Regular injectors, relative to never-injectors, also reported having significantly more social network members who used heroin (81% vs. 41%) and who injected drugs (67% vs. 19%).

Conclusion: Results suggest that young adults who engage in regular IDU have progressed to more severe opioid use problems, are more vulnerable to overdose and HCV infection, and have riskier networks of drug-using peers than their counterparts who have never injected drugs. These findings underscore an urgent need for innovative prevention interventions targeting opioid-using youth, including interventions designed to halt or reverse predictable escalations in opioid use trajectories, including the transition to injection.

Supported by NIDA grant# R01DA035146