Characterizing the Geography of Drug Use Networks and Behaviors Among People Who Inject Drugs in the Baltimore Metropolitan Region.

The geography of injection drug use in the United States continues to evolve and expand outside of urban areas, yet there is little understanding of the extent to which urban and non-urban networks of people who inject drugs (PWID) interact, which has implications for HIV and hepatitis C transmission (HCV). Here, we characterize individuals with mixed geography PWID networks in the Baltimore, Maryland region, as well as prospective associations with injection-related risk behaviors. Nested within the AIDS Linked to the IntraVenous Experience (ALIVE) study, an ongoing community-based cohort of former and current PWID in Baltimore, Maryland, we conducted an ego-centric drug use network survey among n = 237 PWID who reported any injection drug use in the last 12 months from across the metropolitan region in 2018-2019 and examined prospective associations between network geography and injection drug use, sharing, and non-fatal overdose at 6-month follow-up visits. Of the 237 individuals surveyed, 59% (n = 141) had exclusively city-based networks and 41% (n = 87) had mixed-geography networks (defined as ego or at least one network tie with residential location outside of the city). Compared to PWID with uniformly city-based networks, those with mixed-geography networks were more likely to report sharing needles and injection equipment on follow-up, after adjusting for individual characteristics. Network-based interventions focused on PWID who cross geographic borders may be important to stay ongoing HCV transmission and prevent HIV resurgence.