Department of Medical Social Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL.
J Acquir Immune Defic Syndr. 2018 Apr 15;77(5):459-466. doi: 10.1097/QAI.0000000000001620.
Substantial racial disparities exist in HIV infection among young men who have sex with men (YMSM). However, evidence suggests black YMSM do not engage in greater levels of risk behavior. Sexual networks may help explain this paradox. This study used egocentric exponential random graph models to examine variation in concurrency (ie, 2 or more simultaneous partners) and homophily (ie, same race/ethnicity partners) across race/ethnicity groups in a diverse sample of YMSM.
Data for this study come from a longitudinal cohort study of YMSM. Participants (n = 1012) provided data regarding their sexual contacts during the 6 months before their first study visit. A series of egocentric exponential random graph models examined how providing separate estimates for homophily and concurrency parameters across race/ethnicity improved the fit of these models. Networks were simulated using these parameters to examine how local network characteristics impact risk at the whole network level.
Results indicated that homophily, but not concurrency, varied across race/ethnicity. Black participants witnessed significantly higher race/ethnicity homophily compared with white and Latino peers. Extrapolating from these models, black individuals were more likely to be in a connected component with an HIV-positive individual and closer to HIV-positive individuals. However, white individuals were more likely to be in large connected components.
These findings suggest that high racial homophily combined with existing disparities in HIV help perpetuate the spread of HIV among black YMSM. Nonetheless, additional work is required to understand these disparities given that homophily alone cannot sustain them indefinitely.
在男男性行为者（MSM）中，艾滋病毒感染存在着大量的种族差异。然而，有证据表明，黑人 MSM 并没有进行更多的高危行为。性网络可能有助于解释这种悖论。本研究使用个体中心指数随机图模型，在一个多样化的 MSM 样本中，按种族/民族群体考察同时性伴（即 2 个或更多的同时性伴）和同质性（即相同种族/民族的性伴）的变化。
本研究的数据来自对 MSM 的一项纵向队列研究。参与者（n = 1012）在他们第一次研究访问前的 6 个月内提供了有关他们性接触的信息。一系列个体中心指数随机图模型考察了为种族/民族群体提供单独的同质性和同时性伴参数估计如何改善这些模型的拟合度。使用这些参数模拟网络，以考察局部网络特征如何影响整个网络层面的风险。
结果表明，同质性，而不是同时性伴，在种族/民族之间存在差异。与白人及拉丁裔同龄人相比，黑人参与者目睹了更高的种族/民族同质性。从这些模型推断，黑人个体更有可能与 HIV 阳性个体处于一个连接组件中，并且更接近 HIV 阳性个体。然而，白人个体更有可能处于大的连接组件中。
这些发现表明，高种族同质性加上现有的 HIV 差异，有助于艾滋病毒在黑人 MSM 中持续传播。尽管如此，鉴于同质性本身并不能无限期地维持这些差异，还需要进一步的工作来理解这些差异。
