Substance Use
Exploring linkages between injecting-related interpersonal dynamics and high-risk injecting behaviors in dyads of people who inject drugs Neia Prata Menezes* Neia Prata Menezes Maia Scarpetta Julie Bruneau Kimberly Page Torsten Neilands Meghan D. Morris
Injecting behaviors can occur in the context of injecting partnerships, yet the role of injecting dynamics on individual behaviors is not well understood. We conducted secondary analyses of baseline hepatitis C virus (HCV) serology and behavioral survey data to assess linkages between interpersonal factors and behaviors in injecting dyads of people who inject drugs (PWID) (San Francisco, USA and Montreal, Canada, 2017). A 54-item Injecting-Related Interpersonal Relationship Dynamics Scale (IRDS) measured interpersonal factors (injecting-related cooperation, intimacy, risk perception, power imbalance, and trust; α=0.92-0.68). Using Actor-Partner Interdependence Models, we estimated actor and partner effects of individual IRDS scores on equipment and needle sharing. Dyads were indistinguishable. Mixed effect models accounted for a cross-classified data structure with random intercepts for site, actor, and partner. We assumed a Poisson distribution to estimate relative risks (RR) and 95% confidence intervals (95%CI). Among 180 PWID (136 dyads), median age was 30, 74% were male, 21% were non-white, and 49% had HCV infection. Overall, 68% and 18% reported equipment and needle sharing, respectively. Actor’s risk perception (RR=0.89, 95%CI: 0.85-0.92) and partner’s cooperation (RR=1.10, 95%CI: 1.09-1.12) were associated with actor’s equipment sharing. Actor’s (RR=0.81, 95%CI: 0.80-0.83) and partner’s (RR=0.93, 95%CI:0.91-0.95) power were negatively linked to actor’s equipment sharing. Actor’s (RR=1.07, 95%CI: 1.03-1.10) and partner’s (RR=1.20, 95%CI: 1.16-1.24) trust were positively associated with actor’s equipment sharing. We observed similar findings for needle sharing. Injecting-related cooperation and trust may facilitate equipment/needle sharing in injecting dyads; risk and power may have opposite effects, while intimacy had no effect. Accounting for injecting dyad dynamics may better inform individual-level strategies for HCV treatment or harm reduction engagement.
