The effect of the intervention
deaths, death
In our study, we demonstrated a clear and strong effect of the intervention on death outcomes. Among indexes, mortality in the intervention arm compared to the SoC was decreased by more than half. As evident from the multivariable models, the effect of the intervention appears to be mediated by improved immune status, characterized by the CD4 count. Although improved CD4 counts can be plausibly caused only by initiation of ART and resulting viral suppression, these variables did not seem to have an independent effect on mortality in our analysis. Of note, HIV care guidelines since 2015 permitted ART initiation for PWID regardless of CD4 count, which suggests that the observed effect was due to overcoming of other structural and individual-level barriers [Importantly, the study arm remained significant in the multivariable model controlling for clinical, demographic, and substance use variables. We may hypothesize that the intervention may have facilitated access to other health and social services, and may have promoted healthier living in ways that we did not measure, thereby leading to the reduction in non-HIV related deaths in the experimental arm.It should be noted, that participants who attained a CD4 cell count of at least 200 cells/μL continued to experience substantially elevated mortality, about 3 times higher than their HIV-negative partners in our study, and up to 18 times higher than expected in their age-matched general population. These mortality rates cannot be directly compared to other studies of patients on ART, because person time calculation in this analysis was starting from study enrollment and not ART initiation. Nevertheless, it is evident in our study, that PWID who had unsuppressed viral load at baseline and initiated ART afterwards had several times higher death rate compared to other PLWH [The benefits of the integrated intervention were significant not only for direct recipients but also among their injection partners. One plausible mechanism of this effect could be that by reducing barriers to health care for indexes, our intervention also indirectly motivated and helped their partners to seek care, reduce injection drug use, or increase safer injection practices. Specifically, as reported before [