Serosorting among Men at Risk for HIV

描述（由申请人提供）：我们建议在旧金山的男男性行为者（MSM）中获得“HIV血清分类”的横断面和纵向数据。我们将艾滋病毒血清分类广义地定义为通过有意选择具有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。旧金山艾滋病流行的当前阶段是复杂的，总体上无保护肛交（UAS）和性传播疾病（STD）的水平上升，但艾滋病毒的发病率保持稳定。我们假设HIV血清分选可以解释这些明显矛盾的发现；也就是说，与相同艾滋病毒血清状态的伴侣一起增加的UAS会导致性病发病率的增加，但不会导致艾滋病毒发病率的增加。虽然一些证据表明，在旧金山的男男性行为者中，血清分类可能会增加，但仍存在许多问题：在男男性行为者社区中，血清分类作为一种故意采用的艾滋病毒预防策略有多普遍？男男性行为者如何识别具有相同血清状态的伴侣？什么因素导致了坚持血清分类策略的成功或失败？我们需要详细和前瞻性地收集数据，以便回答这些问题，并评估报告的血清分拣与艾滋病毒实际风险之间的因果关系。准确的信息对于消除对血清分拣的误解至关重要，如果它与减少血清不一致的UAS没有因果关系，或者如果它与增加血清分拣成功有因果关系，或者如果它在降低风险方面的作用是混合的，则在降低风险（但不是消除）的背景下构建血清分拣。我们建议采用基于概率的时间-地点抽样方法，在互联网上进行纵向随访，招募以社区为基础的HIV阴性和HIV阳性男男性行为者队列。

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.