论文标题
Youden索引的半参数推断和密度比模型的最佳截止点
Semiparametric Inference of the Youden Index and the Optimal Cutoff Point under Density Ratio Models
论文作者
论文摘要
Youden索引是接收器操作特征曲线的流行摘要统计量。它给出了生物标志物的最佳截止点，以区分患病和健康的个体。在本文中，我们建议通过半参数密度比模型对健康和患病组中个体的生物标志物的分布进行建模。基于此模型，我们使用最大的经验可能性方法来估计Youden索引和最佳截止点。我们进一步建立了所提出的估计器的渐近正态性，并为Youden指数和相应的最佳截止点构造有效的置信区间。当没有检测的下限（LLOD）以及生物标志物有固定且有限的LLOD时，提出的方法会自动涵盖这两种情况。广泛的仿真研究和真实的数据示例用于说明所提出的方法的有效性及其在现有方法中的优势。
The Youden index is a popular summary statistic for receiver operating characteristic curve. It gives the optimal cutoff point of a biomarker to distinguish the diseased and healthy individuals. In this paper, we propose to model the distributions of a biomarker for individuals in the healthy and diseased groups via a semiparametric density ratio model. Based on this model, we use the maximum empirical likelihood method to estimate the Youden index and the optimal cutoff point. We further establish the asymptotic normality of the proposed estimators and construct valid confidence intervals for the Youden index and the corresponding optimal cutoff point. The proposed method automatically covers both cases when there is no lower limit of detection (LLOD) and when there is a fixed and finite LLOD for the biomarker. Extensive simulation studies and a real data example are used to illustrate the effectiveness of the proposed method and its advantages over the existing methods.
