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.