Descriptive statistics of county-level variables.

Background
Timely linkage to care (LTC) is key in the HIV care continuum, as it enables people newly diagnosed with HIV (PNWH) to benefit from HIV treatment at the earliest stage. Previous studies have found LTC disparities by individual factors, but data are limited beyond the individual level, especially at the county level. This study examined the temporal and geographic variations of county-level LTC status across 46 counties in South Carolina (SC) from 2010 to 2018 and the association of county-level characteristics with LTC status.
Methods
All adults newly diagnosed with HIV from 2010 to 2018 in SC were included in this study. County-level LTC status was defined as 1 = “high LTC (≥ yearly national LTC percentage)” and 0 = “low LTC (< yearly national LTC percentage)”. A generalized estimating equation model with stepwise selection was employed to examine the relationship between 29 county-level characteristics and LTC status.
Results
The number of counties with high LTC in SC decreased from 34 to 21 from 2010 to 2018. In the generalized estimating equation model, six out of 29 factors were significantly associated with LTC status. Counties with a higher percentage of males (OR = 0.07, 95%CI: 0.02~0.29) and persons with at least four years of college (OR = 0.07, 95%CI: 0.02~0.34) were less likely to have high LTC. However, counties with more mental health centers per PNWH (OR = 45.09, 95%CI: 6.81~298.55) were more likely to have high LTC.
Conclusions
Factors associated with demographic characteristics and healthcare resources contributed to the variations of LTC status at the county level. Interventions targeting increasing the accessibility to mental health facilities could help improve LTC.

背景
及时衔接护理（Linkage to Care, LTC）是HIV护理连续照护体系的核心环节，可使新诊断HIV感染者（People Newly Diagnosed with HIV, PNWH）在最早阶段获益于HIV治疗。既往研究已发现基于个体因素的LTC差异，但目前针对个体层面以上的LTC相关数据较为匮乏，尤其是县级层面的数据。本研究针对2010至2018年美国南卡罗来纳州（South Carolina, SC）46个县级行政区的县级LTC现状，分析其时间与地理分布差异，并探究县级特征与LTC现状之间的关联。

方法
本研究纳入了2010至2018年SC地区所有新诊断HIV感染的成年患者。县级LTC现状定义为：1=高LTC水平（≥年度全国LTC占比），0=低LTC水平（<年度全国LTC占比）。本研究采用带有逐步筛选法的广义估计方程模型，分析29项县级特征与LTC现状之间的关联。

结果
2010至2018年，SC地区高LTC水平的县级行政区数量从34个降至21个。广义估计方程模型结果显示，29项影响因素中有6项与LTC现状存在显著关联。男性人口占比更高的县级行政区（比值比OR=0.07，95%置信区间CI：0.02~0.29）以及本科及以上学历人口占比更高的县级行政区（OR=0.07，95%CI：0.02~0.34），其高LTC水平的概率更低。但每例新诊断HIV感染者（PNWH）所对应的精神卫生中心数量更多的县级行政区（OR=45.09，95%CI：6.81~298.55），其高LTC水平的概率更高。

结论
人口统计学特征与医疗资源相关因素，是导致县级LTC现状存在差异的重要原因。针对提升精神卫生设施可及性的干预措施，有助于改善LTC水平。