Social networks, secondary syringe exchange, and opioid agonist therapy retention among people who inject drugs in Hartford, CT

Background: Opioid agonist therapies (OAT) and harm reduction such as syringe service programs (SSP) have been shown to be effective in preventing adverse outcomes such as overdose deaths, HIV and Hepatitis C in-fections among people who inject drugs (PWID). The importance of social network influence on disease trans-mission is well established, yet the interplay between harm reduction and network structures is, generally, not well understood. This study aims to analyze how social networks can mediate the harm reduction effects asso-ciated with secondary exchange through syringe service programs (SSP) and opioid agonist therapies (OAT) among injection network members.Methods: Sociometric data on networks on people who inject drugs from Hartford, CT, which were collected in 2012-2013, provided assessment of risk behaviors among 1574 injection network members, including partici-pation in OAT and SSP. Subject's network characteristics were examined in relation to retention in OAT, as well as secondary syringe exchange using exponential random graph model (ERGM) and regression.Results: Based on the analysis, we found that probability of individuals being retained in OAT was positively associated with the OAT retention status of their peers within the network. Using simulations, we found that higher levels of positive correlation of OAT retention among network members can result in reduced risk of transmission of HIV to network partners on OAT. In addition, we found that secondary syringe exchange engagement was associated with higher probability of sharing of paraphernalia and unsterile needles at the network level.Conclusions: Understanding how networks mediate risk behaviors is crucial for making progress toward ending the HIV epidemic.