Participation Dynamics in Population-Based Longitudinal HIV Surveillance in Rural South Africa

Population-based HIV surveillance is crucial to inform understanding of the HIV pandemic and evaluate HIV interventions, but little is known about longitudinal participation patterns in such settings. We investigated the dynamics of longitudinal participation patterns in a high HIV prevalence surveillance setting in rural South Africa between 2003 and 2012, taking into account demographic dynamics. At any given survey round, 22,708 to 30,495 persons were eligible. Although the yearly participation rates were relatively modest (26% to 46%), cumulative rates increased substantially with multiple recruitment opportunities: 68% of eligible persons participated at least once, 48% at least twice and 31% at least three times after five survey rounds. We identified two types of study fatigue: at the individual level, contact and consent rates decreased with multiple recruitment opportunities and, at the population level, these rates also decreased over calendar time, independently of multiple recruitment opportunities. Using sequence analysis and hierarchical clustering, we identified three broad individual participation profiles: consenters (20%), switchers (43%) and refusers (37%). Men were over represented among refusers, women among consenters, and temporary non-residents among switchers. The specific subgroup of persons who were systemically not contacted or refusers constitutes a challenge for population-based surveillance and interventions.

基于人群的艾滋病病毒（HIV）监测对于明晰艾滋病流行态势、评估艾滋病防控干预措施至关重要，但目前学界对此类监测场景下的纵向参与模式仍知之甚少。本研究针对南非农村地区某高HIV感染率的监测现场，于2003至2012年间开展调查，剖析其纵向参与模式的动态特征，并纳入人口统计学动态变化因素进行分析。
每一轮调查中，符合纳入标准的研究对象人数介于22708至30495人之间。尽管年度参与率相对偏低（26%至46%），但随着多次招募机会的增加，累计参与率大幅提升：在完成5轮调查后，68%的符合标准者至少参与过1次，48%至少参与过2次，31%至少参与过3次。
本研究识别出两类研究疲劳现象：在个体层面，随着多次招募机会的增加，研究对象的联系成功率与知情同意率均有所下降；在群体层面，即便不受多次招募机会的影响，上述两项指标也会随自然时间推移而降低。
本研究采用序列分析与层级聚类法，将个体参与特征划分为三大类别：依从者（20%）、转换者（43%）与拒访者（37%）。拒访者群体中男性占比偏高，依从者群体以女性为主，而转换者群体则以临时非本地居民居多。那些始终未被成功联系或系统性拒访的特定亚群，给基于人群的监测工作与防控干预措施带来了挑战。