Ngondi Jeremiah, Reacher Mark, Matthews Fiona, Brayne Carol, Emerson Paul
Institute of Public Health, University of Cambridge, Cambridge, England.
Bull World Health Organ. 2009 Feb;87(2):143-51. doi: 10.2471/blt.07.046326.
Reliable population-based prevalence data are essential for planning, monitoring and evaluating trachoma control programmes and understanding the scale of the problem, yet they are not currently available for 22 out of 56 trachoma-endemic countries. Three survey methods have been advocated for trachoma: cluster random sampling (CRS); trachoma rapid assessment (TRA); and acceptance sampling trachoma rapid assessment (ASTRA). Our review highlights the benefits of CRS being simple, efficient, repeatable and giving population-based prevalence estimates of all signs of trachoma. There are limitations to TRA, which include: non-representative sampling; does not estimate prevalence; and lacks consistency and accuracy. ASTRA advocates small sample sizes but it is relatively complex, may result in imprecise prevalence estimates and does not estimate cicatricial signs of trachoma. We conclude that CRS should therefore remain the 'gold' standard for trachoma surveys. However, among the CRS surveys reviewed, we also found several methodological deficiencies of sample-size calculations, standardization of trachoma graders, reporting of confidence intervals of prevalence estimates, variability of age groups for presentation of age-specific prevalence, and lack of estimation of district prevalence estimates. Properly conducted surveys will be crucial if the objective of global elimination of blinding trachoma is to be charted and realized. Harmonization of survey methods will enhance the conduct and comparability of trachoma surveys needed for reliable mapping of prevalence within endemic countries. Consistent with WHO recommendations, we advocate for continued use of CRS as the survey design of choice for trachoma control programmes and propose ways of improving future surveys based on this method.
基于可靠人群的患病率数据对于沙眼控制项目的规划、监测和评估以及了解问题的规模至关重要,但在56个沙眼流行国家中,目前有22个国家没有此类数据。针对沙眼,人们提倡三种调查方法:整群随机抽样(CRS);沙眼快速评估(TRA);以及验收抽样沙眼快速评估(ASTRA)。我们的综述强调了CRS的优点,即简单、高效、可重复,并能给出基于人群的所有沙眼体征患病率估计值。TRA存在局限性,包括:抽样不具代表性;不估计患病率;缺乏一致性和准确性。ASTRA主张小样本量,但它相对复杂,可能导致患病率估计不准确,且不估计沙眼的瘢痕体征。我们得出结论,因此CRS应仍然是沙眼调查的“黄金”标准。然而,在我们审查的CRS调查中,我们还发现了样本量计算、沙眼分级员标准化、患病率估计置信区间报告、特定年龄患病率呈现的年龄组变异性以及缺乏地区患病率估计等几个方法学缺陷。如果要规划并实现全球消除致盲性沙眼的目标,进行恰当的调查将至关重要。统一调查方法将加强沙眼调查的实施和可比性,这对于在流行国家可靠绘制患病率地图是必要的。与世界卫生组织的建议一致,我们主张继续使用CRS作为沙眼控制项目首选的调查设计,并提出基于此方法改进未来调查的方法。