Greiner M, Franke C R, Böhning D, Schlattmann P
Institut für Parasitologie und Tropenveterinärmedizin am Fachbereich Veterinärmedizin, Freie Universität, Berlin, Germany.
Acta Trop. 1994 Feb;56(1):97-109. doi: 10.1016/0001-706x(94)90044-2.
In the serodiagnosis of tropical infectious diseases, cut-off values are often established by using sera from individuals living under moderate climatic conditions, not exposed to the risk of infection (non-endemic controls). This approach guarantees the disease-free status of the individuals within that control group but leads to an assembly of samples which are not representative for the disease-free individuals of the target population (selection bias). Using data from an epidemiological study of Trypanosoma evansi infection in dogs, two alternative methods to construct cut-off values for a T. evansi antibody ELISA are described which are solely based on a distribution analysis of the data from the endemic animals. By cluster analysis these data could be divided into 'high', 'intermediate' and 'low responders'. High responders could also be identified by using the computer-assisted analysis of mixtures (C.A.MAN). Conventional cut-offs were calculated from a group of non-endemic individuals. A receiver operating characteristic (ROC) analysis was performed to demonstrate the impact of the choice of cut-offs on the test specificity and on the estimated seroprevalence among the endemic population. The data indicate that distribution analysis, especially the mixture analysis (C.A.MAN), are valuable tools for the unbiased estimation of seroprevalence when representative negative controls are not available.
在热带传染病的血清学诊断中，临界值通常是通过使用生活在气候温和条件下、未暴露于感染风险（非流行对照）个体的血清来确定的。这种方法保证了该对照组个体的无病状态，但导致了一组不能代表目标人群无病个体的样本集合（选择偏倚）。利用犬伊氏锥虫感染的流行病学研究数据，描述了两种构建伊氏锥虫抗体ELISA临界值的替代方法，这些方法仅基于来自流行地区动物数据的分布分析。通过聚类分析，这些数据可分为“高反应者”、“中反应者”和“低反应者”。高反应者也可以通过计算机辅助混合物分析（C.A.MAN）来识别。常规临界值是从一组非流行个体计算得出的。进行了受试者工作特征（ROC）分析，以证明临界值选择对检测特异性和流行人群中估计血清阳性率的影响。数据表明，当没有代表性的阴性对照时，分布分析，尤其是混合物分析（C.A.MAN），是无偏估计血清阳性率的有价值工具。
