Theme: Epidemiology & Public Health Research Year: 2019
Background: Injection drug use (IDU) has become a significant public health problem. IDU has been
related closely with the opioid epidemic; however, trends in IDU of other substances have been
increasing over the same time period. Patterns of different substances injected among people who
inject drugs (PWID) may be associated with increased risky behavior and HIV/HCV acquisition. This study
aims to determine the injection drug use patterns among PWID accessing a syringe service program
(SSP) for the first time.
Methods: A latent class analysis (LCA) was performed on 837 participants enrolling in a syringe service
program (SSP) for the first time. Associations between classes on socio-demographic variables, high-risk
injection practices, overdose, and HIV/HCV status were analyzed using the automated 3-step procedure
in latent class regression in Mplus.
Results: A three-class solution was determined: Heroin-primary injectors (73.6%), Methamphetamineonly injectors (10.4%) and Polysubstance injectors (16.0%). Compared to Heroin-primary injectors,
Polysubstance injectors were more likely to report lower income (OR=1.68, 95% CI: 1.02-2.75),
homelessness (OR=2.58, 95% CI: 1.60-4.15), ever overdose (OR=2.32, 95% CI: 1.39-3.87), injecting more
than seven times a day (OR=2.06, 95% CI: 1.22-3.47), sharing works (OR=2.92, 95% CI: 1.81-4.68), and
injecting in a public setting (OR=5.49, 95% CI: 3.27-9.21). In addition, Methamphetamine-only injectors
were more likely to be male (OR=15.77, 95% CI: 1.62-153.5), more educated (OR=3.33, 95% CI: 1.82-
6.25), have higher income (OR=1.82, 95% CI: 1.06-3.13), report stable housing (OR=1.96, 95% CI: 1.05-
3.57), report gay/bisexual orientation (OR=32.85, 95% CI: 16.58-65.12), and private (in home) injection
(OR=3.97, 95% CI: 1.98-7.95) compared to the Heroin-primary injectors.
Conclusion: Results from this study show varying PWID populations that are accessing syringe services.
SSPs are a pivotal touchpoint to these populations, and targeted preventive interventions among
differing injection drug use populations may be needed to further reduce HIV and HCV risk-related
Disclosure of Interest Statement: This work was supported in part by grant funding through the
Frontlines of Communities in the United States (FOCUS), Gilead Sciences. The FOCUS program (a branch
of Gilead’s Government Affairs division) partners with health care providers, government agencies, and
community organizations to implement HIV and hepatitis C virus screening programs and develop
replicable models that embody best practices in screening and linkage to care. The program pays for
partial salary support for principal investigators to develop protocols and manage the screening
program, administrative staff to assist with data acquisition and linkage, and meeting-related travel