Effects of a social network intervention on HIV seroconversion among people who inject drugs in Ukraine: moderation by network gender composition

BACKGROUND: Women who inject drugs in Ukraine are disproportionately burdened by HIV. To help address the needs of this population, a greater understanding of how interventions may uniquely benefit women who inject drugs is needed. METHODS: Data come from a randomized controlled trial of a social network intervention targeting people who inject drugs in Ukraine (N = 1195). Indexes, plus two of their injection network members, received HIV testing and counseling (control arm) or HIV testing and counseling plus a social network intervention (intervention arm), in which indexes were trained to influence network members’ risk behaviors. We used Cox regressions with interaction terms to assess differences in time to HIV seroconversion between arms by network gender composition and gender of the index. For significant interaction terms, we calculated simple effects, generated survival functions using Kaplan–Meier methods, and compared survival curves using log-rank tests. RESULTS: At 12 months, there were 45 seroconversions among women (40.0 [28.3, 51.7] per 100 person years) and 111 among men (28.4 [23.1, 33.6] per 100 person years) in the control arm; there were 27 seroconversions among women (17.1 [10.7, 23.6] per 100 person years) and 77 among men (18.7 [14.5, 22.9] per 100 person years) in the intervention arm. Network gender composition (but not gender of the index) moderated the intervention effect on HIV incidence (p < 0.05). Specifically, the intervention appeared to be even more protective against HIV acquisition as female gender composition increased. In the intervention arm, the HIV seroconversion hazard rate was 44% lower with 1 network female; 61% lower with 2 network females; and 72% lower with 3 network females. CONCLUSIONS: A greater number of women in an injection network, coupled with the provision of risk-reduction strategies, is associated with HIV risk-mitigation, though the mechanisms through which this occurs remain unclear. Findings can support new research and practice directions that prioritize women who inject drugs and more thoughtfully support their health and wellbeing.