Latent Class Modeling of Syndemic Burden and HIV-Related Sexual Risk Behaviors among Urban MSM

In the context of decreasing or plateauing HIV incidence among multiple risk groups in United States, new HIV infections among gay, bisexual, and other men who have sex with men (MSM) continue to rise. Syndemic theory has become a well-established framework for the explanation of how individual experiences and social conditions influence both an individual’s disease experience and the distribution of disease across populations. This framework is currently defined as “a set of enmeshed and mutually enhancing health problems that, working together in a context of deleterious social and physical conditions that increase vulnerability, [and] significantly affect the overall disease status of a population.”1 An important and robust body of literature has been amassed investigating syndemic burden and its association with HIV status, HIV incidence, HIV-related sexual risk behaviors, and more recently, antiretroviral (ART) medication adherence and viral suppression among HIV-positive MSM. Many of the studies that comprise this literature have several things in common. They are mostly focused on enmeshed individual-level risk factors; that is, this literature largely focuses on co-occurrence of these health problems and the increased vulnerability to HIV that may develop as a result. Even more importantly, most of these studies focused on a small subset of these risk factors: childhood sexual abuse, depression, intimate partner violence, polydrug use. These studies also largely ignore the synergy (defined as biological interaction on the additive scale or deviations from additivity) implied in the mutually enhancing language of this framework. Finally, this literature is also unable to account for the “deleterious social and physical conditions” that give context to the individual-level burden. Taken together, the body of studies present an important but not fully realized use of this framework. This dissertation seeks to investigate all three major facets of the syndemic framework: the individual-level co-occurring syndemic factors, the implied synergy, and the social and physical conditions that surround and influence the individual. It will do so in three steps, broadly defined by a systematic literature review followed by two analytic papers. The literature review will serve as a guide to the syndemics literature among MSM, and will identify the constellation of experiences that have been identified as syndemic factors. The identified experiences will be used to guide the first analytic paper, which will incorporate those experiences into syndemic burden, which will then be modeled using latent class modeling (LCA) to investigate if there are any patterns of syndemic burden that may be important to intervention development. This first analytic paper will also explicitly investigate synergy by calculating the attributable proportion due to interaction (AP). Finally, the second analytic paper will incorporate the “deleterious social and physical conditions” using multilevel latent class modeling (MLCA).