Serosorting among Men at Risk for HIV

描述（由申请人提供）：我们建议在弗朗西斯科男男性行为者（MSM）中获得关于“HIV血清分选”的横截面和纵向数据。我们将艾滋病毒血清分选广泛定义为通过有意选择相同血清状态的性伴侣或根据伴侣的血清状态修改性行为来减少艾滋病毒感染或传播的多种策略。旧金山弗朗西斯科艾滋病毒流行的当前阶段是复杂的，总体无保护的肛交（UAS）和性传播疾病（STD）水平不断上升，但艾滋病毒发病率稳定。我们假设，艾滋病毒血清分选可以解释这些明显矛盾的结果，即，增加UAS与合作伙伴的相同的艾滋病毒血清状态是导致性病发病率的增加，但不是艾滋病毒的发病率。虽然一些证据表明，血清分选可能会增加在旧金山弗朗西斯科的男男性接触者，许多问题仍然存在：如何普遍的血清分选作为一个故意采取的艾滋病毒预防策略在男男性接触者社区？MSM如何识别具有相同血清状态的伴侣？哪些因素影响血清分选策略的成功或失败？我们需要详细和前瞻性收集的数据，以回答这些问题，并评估报告的血清分选和艾滋病毒的实际风险之间的因果关系。准确的信息对于消除对血清分选的误解至关重要，如果它与减少血清不一致的UAS没有因果关系，或者对于增加血清分选的成功，如果它与减少血清不一致的UAS没有因果关系，或者对于在风险降低（但不是消除）的背景下制定血清分选，如果它在降低风险中的作用是混合的。我们建议采用基于概率的时间-地点抽样方法，通过互联网进行纵向随访，招募一个以社区为基础的HIV阴性和HIV阳性MSM队列。

DESCRIPTION (provided by applicant): We propose to obtain cross-sectional and longitudinal data on "HIV serosorting" among men who have sex with men (MSM) in San Francisco. We broadly define HIV serosorting as diverse strategies to reduce HIV acquisition or transmission by intentionally selecting sexual partners of the same serostatus or by modifying sexual practices depending on the partner's serostatus. The current phase of the HIV epidemic in San Francisco is complex with rising levels of overall unprotected anal sex (UAS) and sexually transmitted diseases (STD), yet stable HIV incidence. We hypothesize that HIV serosorting may explain these apparently contradictory findings; that is, increasing UAS with partners of the same HIV serostatus is leading to increases in STD incidence but not HIV incidence. While some evidence suggests serosorting may be increasing among MSM in San Francisco, many questions remain: How prevalent is serosorting as a deliberately adopted HIV prevention strategy in the MSM community? How do MSM identify partners of the same serostatus? What factors contribute to the success or failure of adhering to serosorting strategies? We need detailed and prospectively collected data in order to answer these questions and to assess the causal relationship between reported serosorting and actual risk for HIV. Accurate information is essential for dispelling misperceptions of serosorting if it is not causally associated with reducing serodiscordant UAS, or for increasing serosorting success if it is, or for framing serosorting in the context of risk reduction (but not elimination) if its in role in reducing risk is mixed. We propose to recruit a community-based cohort of HIV- negative and HIV-positive MSM using a probability-based time-location sampling method with longitudinal follow-up over the internet.