Abstract
Background: The theory of syndemics—whereby synergism between co-occurring psychosocial epidemics exacerbates health outcomes—has informed efforts to quantify the risk of contracting HIV, but it has rarely been used to quantify HIV transmission risk among people living with HIV (PLWH). To improve treatment as prevention (TasP) efforts, greater insight is needed about how syndemic factors influence viral suppression and biobehavioral transmission risk behavior among PLWH. Method: Data were from 14,261 PLWH receiving care through the Centers for AIDS Research Network of Integrated Clinical Systems at seven sites from 2007 to 2017. Syndemic factors (depressive symptoms, anxiety symptoms, drug use, and alcohol use) and sexual behaviors were collected through patient-reported outcomes and measures (PROs) at least 4–6 months apart. Using estimates of per-sex-act HIV transmission rates, estimated HIV transmissions were computed for each observation period. Hierarchical linear modeling was used to model the number of syndemic factors, sexual risk group (cisgender heterosexual men, cisgender men who have sex with men (MSM), cisgender men of unknown sexual orientation, cisgender women, and transgender women), and time in care as predictors of estimated HIV transmissions. Results: When comparing patients to one another based on their average number of syndemic factors, each additional syndemic factor in patients’ averages was associated with 0.527 estimated HIV transmissions per 100 patients annually. When comparing patients to themselves across the available time period, each increase in patients’ individual number of syndemic factors for a particular observation period was associated with 0.342 estimated transmissions per 100 patients annually. Cisgender women were estimated to contribute to 0.865 fewer transmissions per 100 patients annually than the referent group (cisgender MSM). Conclusion: Syndemic factors among PLWH appear to be predictive of biobehavioral HIV transmission risk as measured by estimates of infections accounting for sexual behavior and HIV RNA viral load suppression. Psychosocial interventions to address these syndemic factors in clinical settings may be an effective means of secondary HIV prevention.