Spatio-Temporal Analysis of Smear-Positive Tuberculosis in the Sidama Zone, Southern Ethiopia

BackgroundTuberculosis (TB) is a disease of public health concern, with a varying distribution across settings depending on socio-economic status, HIV burden, availability and performance of the health system. Ethiopia is a country with a high burden of TB, with regional variations in TB case notification rates (CNRs). However, TB program reports are often compiled and reported at higher administrative units that do not show the burden at lower units, so there is limited information about the spatial distribution of the disease. We therefore aim to assess the spatial distribution and presence of the spatio-temporal clustering of the disease in different geographic settings over 10 years in the Sidama Zone in southern Ethiopia.MethodsA retrospective space–time and spatial analysis were carried out at the kebele level (the lowest administrative unit within a district) to identify spatial and space-time clusters of smear-positive pulmonary TB (PTB). Scan statistics, Global Moran’s I, and Getis and Ordi (Gi*) statistics were all used to help analyze the spatial distribution and clusters of the disease across settings.ResultsA total of 22,545 smear-positive PTB cases notified over 10 years were used for spatial analysis. In a purely spatial analysis, we identified the most likely cluster of smear-positive PTB in 192 kebeles in eight districts (RR= 2, pConclusionThe study found variations in CNRs and significant spatio-temporal clusters of smear-positive PTB in the Sidama Zone. The findings can be used to guide TB control programs to devise effective TB control strategies for the geographic areas characterized by the highest CNRs. Further studies are required to understand the factors associated with clustering based on individual level locations and investigation of cases.背景 结核病（Tuberculosis, TB）是一类受公共卫生高度关注的疾病，其在不同地区的分布差异受社会经济状况、艾滋病病毒（HIV）感染负担、医疗系统可及性与服务性能的影响而各不相同。埃塞俄比亚是结核病高负担国家，其结核病病例报告率（Case Notification Rates, CNRs）存在区域差异。然而，当前结核病防控项目的报告数据通常仅在较高行政层级汇总发布，无法反映基层行政单元的疾病负担水平，因此关于该疾病空间分布的公开信息十分有限。本研究旨在评估埃塞俄比亚南部锡达马区（Sidama Zone）10年间不同地理场景下结核病的空间分布特征及其时空聚集性。 方法 本研究以乡级行政单元（kebele，即行政区内最低层级行政单位）为分析尺度，开展回顾性时空与空间分析，以识别痰涂片阳性肺结核（smear-positive pulmonary TB, PTB）的空间及时空聚集区域。研究综合采用扫描统计量、全局莫兰I指数（Global Moran’s I）以及盖蒂-奥德Gi*统计量（Getis and Ord's Gi*），对不同地理场景下结核病的空间分布与聚集特征进行分析。 结果 本研究共纳入10年间报告的22545例痰涂片阳性肺结核病例用于空间分析。纯空间分析结果显示，在8个行政区的192个乡级单元中识别出痰涂片阳性肺结核的最主要聚集区域（相对危险度RR=2, p）。 结论 本研究发现锡达马区的结核病病例报告率存在区域差异，且痰涂片阳性肺结核存在显著的时空聚集性。研究结果可为结核病防控项目提供决策依据，帮助其针对病例报告率最高的地理区域制定高效的结核病防控策略。未来仍需开展进一步研究，以明确基于个体位置的聚集性相关影响因素，并对病例开展针对性调查。