Discussion
HIV seroconversion
In this study, we explored the extent to which network gender composition and index gender moderated the effects of a social network intervention on HIV seroconversion among PWID in Ukraine. Though women comprised only one quarter of the sample, our findings revealed significant moderation by network gender composition but not by index gender. Our first sensitivity analysis also revealed significant moderation by network gender composition even though we excluded the index, while our second sensitivity analysis showed a sustained, constant trend of reduced risk among women and a decreasing trend of reduced risk among men as the number network females increased. These findings contribute to the broader literature that has shown social network approaches to be effective in documenting and reducing unsafe behaviors among PWID across diverse contexts, including Ukraine [Our main analysis (and first sensitivity analysis) revealed a more robust intervention effect on HIV seroconversion among participants with more women in their injection network, which recalls prior research showing a protective effect for PWID with a greater proportion of women in their networks [Other explanations for the moderation effect could be related to features of women’s injection networks. Research in other contexts has indicated that the injection networks of women who inject drugs tend to be relatively small and built on trust and close bonds with others [Our second sensitivity analysis showed support for what we found in our main analysis, demonstrating that men benefited more from the intervention as the number of women in their injection network increased. While women were shown to have benefited regardless of whether other women were in their network, it should be recalled that our sample size of women was a third of our sample size of men, and therefore more prone to parameter estimation error. Nevertheless, findings from both the main and sensitivity analyses do suggest that women uniquely benefited from the intervention and may have even played a role in helping facilitate men’s benefit as well. Again, whether this was due to women’s unique contribution to the network or women’s self-selecting into networks that are inherently safer is unclear, but this lack of clarity on the mechanism does not negate the fact that the presence of women in the network seems to signal greater potential for safer behaviors and reduced HIV risk. Future research should closely examine the mechanisms explaining the role of women in injection risk networks (i.e., whether women promote safer behavior, and/or they self-select into safer networks).Importantly, we did not assess the full extent of the size or gender composition of participants’ real-world injection networks, as the very nature of the intervention dictated that participants only recruit two of their injection network members. Therefore, participants’ actual injection networks could have been much larger and differently composed than what was indicated in our findings. Unmeasured network links could produce a confounding effect, especially if women’s injection networks vary substantially from those of men [There was no moderation effect by index gender. Given women’s more subjugated social position relative to men in Ukraine [