The role of social networks and geography on risky injection behaviors of young persons who inject drugs

Background: Little is known about young persons who inject drugs (PWID), who are increasingly from suburban communities and predominantly non-Hispanic white. Methods: We conducted a cross-sectional personal network (egocentric) and geographic study of young PWID and their drug-using, sexual, and support network members in 2012-13 in metropolitan Chicago, Illinois, U.S. Results: We enrolled 164 young (median age = 26), mostly male (65%), non-Hispanic white PWID (71%), with a self-reported HCV prevalence of 13%. Many (59%) reported multiple residences (i.e., were transient) in the past year, 45% of whom reported living in both urban and suburban places (i.e., were cross-over transients). In multivariable analyses that adjusted for participant and network member characteristics, (1) large injection networks were more common among homeless participants; and (2) syringe sharing was (a) highest among cross-over transients compared to suburban (OR= 4.19 95% CI 1.69-10.35) and urban only residents (OR= 2.91 95% CI 1.06-8.03), (b) higher among HCV-unknown compared HCV-negative participants (OR= 4.62 95% CI 1.69-10.35), (c) more likely with network members who were cross-over transients compared to urban (OR =4.94, 95% CI 2.17-11.23) and (d) less likely with network members with HCV-unknown compared to HCV-negative status (OR= 0.4 95% CI 0.19-0.84). Conclusions: We identified homelessness as a significant risk factor for large networks and cross-over transience as a significant risk factor for syringe sharing. Further research is needed to understand the role of geographic factors promoting higher risk among these crossover transient PWID. (C) 2015 Elsevier Ireland Ltd. All rights reserved.