Kandala Ngianga-Bakwin, Campbell Eugene K, Rakgoasi Serai Dan, Madi-Segwagwe Banyana C, Fako Thabo T
University of Warwick, Warwick Medical School, Division of Health Sciences; Populations, Evidence and Technologies Group, Warwick Evidence, Coventry, UK.
HIV AIDS (Auckl). 2012;4:95-102. doi: 10.2147/HIV.S30537. Epub 2012 Jul 18.
Botswana has the second-highest human immunodeficiency virus (HIV) infection rate in the world, with one in three adults infected. However, there is significant geographic variation at the district level and HIV prevalence is heterogeneous with the highest prevalence recorded in Selebi-Phikwe and North East. There is a lack of age-and location-adjusted prevalence maps that could be used for targeting HIV educational programs and efficient allocation of resources to higher risk groups.
We used a nationally representative household survey to investigate and explain district level inequalities in HIV rates. A Bayesian geoadditive mixed model based on Markov Chain Monte Carlo techniques was applied to map the geographic distribution of HIV prevalence in the 26 districts, accounting simultaneously for individual, household, and area factors using the 2008 Botswana HIV Impact Survey.
Overall, HIV prevalence was 17.6%, which was higher among females (20.4%) than males (14.3%). HIV prevalence was higher in cities and towns (20.3%) than in urban villages and rural areas (16.6% and 16.9%, respectively). We also observed an inverse U-shape association between age and prevalence of HIV, which had a different pattern in males and females. HIV prevalence was lowest among those aged 24 years or less and HIV affected over a third of those aged 25-35 years, before reaching a peak among the 36-49-year age group, after which the rate of HIV infection decreased by more than half among those aged 50 years and over. In a multivariate analysis, there was a statistically significant higher likelihood of HIV among females compared with males, and in clerical workers compared with professionals. The district-specific net spatial effects of HIV indicated a significantly higher HIV rate of 66% (posterior odds ratio of 1.66) in the northeast districts (Selebi-Phikwe, Sowa, and Francistown) and a reduced rate of 27% (posterior odds ratio of 0.73) in Kgalagadi North and Kweneng West districts.
This study showed a clear geographic distribution of the HIV epidemic, with the highest prevalence in the east-central districts. This study provides age- and location-adjusted prevalence maps that could be used for the targeting of HIV educational programs and efficient allocation of resources to higher risk groups. There is need for further research to determine the social, cultural, economic, behavioral, and other distal factors that might explain the high infection rates in some of the high-risk areas in Botswana.
博茨瓦纳的人类免疫缺陷病毒（HIV）感染率位居世界第二，每三名成年人中就有一人感染。然而，地区层面存在显著的地理差异，HIV流行情况不均一，在塞莱比-菲克韦和东北部地区记录的流行率最高。缺乏可用于针对HIV教育项目以及向高风险群体有效分配资源的年龄和地点调整后的流行率地图。
我们使用了一项具有全国代表性的家庭调查来调查和解释地区层面HIV感染率的不平等情况。应用基于马尔可夫链蒙特卡罗技术的贝叶斯地理加性混合模型来绘制26个地区HIV流行率的地理分布，同时使用2008年博茨瓦纳HIV影响调查考虑个体、家庭和地区因素。
总体而言，HIV流行率为17.6%，女性（20.4%）高于男性（14.3%）。城镇地区的HIV流行率（20.3%）高于城中村和农村地区（分别为16.6%和16.9%）。我们还观察到年龄与HIV流行率之间呈倒U形关联，男性和女性的模式不同。24岁及以下人群的HIV流行率最低，25 - 35岁人群中超过三分之一受HIV影响，在36 - 49岁年龄组达到峰值，之后50岁及以上人群的HIV感染率下降超过一半。在多变量分析中，女性感染HIV的可能性在统计学上显著高于男性，文职人员高于专业人员。特定地区的HIV净空间效应表明，东北部地区（塞莱比-菲克韦、索瓦和弗朗西斯敦）的HIV感染率显著高出66%（后验优势比为1.66），而卡拉哈迪北区和奎嫩西区的感染率降低了27%（后验优势比为0.73）。
本研究显示了HIV疫情的明确地理分布，东部中部地区流行率最高。本研究提供了年龄和地点调整后的流行率地图，可用于针对HIV教育项目以及向高风险群体有效分配资源。需要进一步研究以确定可能解释博茨瓦纳一些高风险地区高感染率的社会、文化、经济、行为和其他远端因素。
