Serosorting among Men at Risk for HIV

描述(由申请人提供)：我们建议获得旧金山男男性行为者(MSM)中“HIV血清检测”的横截面和纵向数据。我们广泛地将艾滋病毒血清检测定义为通过故意选择具有相同血清状态的性伴侣或通过根据伴侣的血清状态改变性行为来减少艾滋病毒感染或传播的不同策略。旧金山目前的艾滋病毒流行阶段很复杂，总体无保护肛交(UAS)和性传播疾病(STD)的水平不断上升，但艾滋病毒发病率保持稳定。我们假设HIV血清检测可以解释这些明显相互矛盾的发现；也就是说，与具有相同HIV血清状态的伴侣增加UA会导致STD发病率的增加，但不会导致HIV发病率的增加。虽然一些证据表明，在旧金山的MSM中，血清滴注可能正在增加，但许多问题仍然存在：在MSM社区中，血清滴定作为一种故意采用的艾滋病毒预防策略的流行程度如何？男男性接触者如何识别具有相同血清状态的伴侣？坚持血清滴定策略的成败由哪些因素决定？我们需要详细和前瞻性收集的数据，以回答这些问题，并评估报告的血清滴定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滴定的误解是至关重要的，如果它与减少血清不一致的UA没有因果关系，或者如果它与减少血清不一致的UA有因果关系，那么对于增加血清滴定的成功率是至关重要的，或者如果它在降低风险方面的作用是混合的，那么对于在降低风险(但不是消除)的背景下框定血清滴定是至关重要的。我们建议在社区招募HIV阴性和HIV阳性的MSM，采用基于概率的时间-地点抽样方法，并通过互联网进行纵向跟踪。

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.