作为医疗保健的基本组成部分,疾病筛查非常重要。通常,对特定疾病的两种筛查测试进行比较,以确定最佳筛查策略,例如,直肠指检(DRE)和血清前列腺特异性抗原(PSA)水平用于筛查前列腺癌。理想情况下,如果对每个被筛查的人进行黄金标准测试,以确定他们的真实疾病状态,可以评估两次测试之间的准确性差异。在实践中,然而,通常只有在至少一项筛查测试中测试呈阳性的人才能接受黄金标准测试,通常是侵入性的,由于道德原因,不能应用于两项测试结果均为阴性的人。在这种情况下,无法确定两个测试之间准确性度量差异的估计,因此,在这个框架内的推理问题是具有挑战性的。在这篇文章中,使用灵敏度和特异性作为测试准确性的衡量标准,我们证明了两个测试之间的差异是区间识别的,以可估计的尖锐界限为界。这里,我们利用解决部分识别参数的推理问题的方法,为边界的估计器开发渐近正态,并为差异构造置信区间。通过仿真研究评估了所构造的置信区间的差异及其尖锐界限的性能。我们还将所提出的方法应用于前列腺癌实例,以比较DRE和PSA的准确性。
As a fundamental component of health care, disease screening is of highly importance. Oftentimes, two screening tests for a specific disease are compared in order to determine an optimal screening policy, for example, the digital rectal examination (DRE) and serum prostate specific antigen (PSA) level for screening prostate cancer. Ideally, if a gold standard test is given to each individual being screened to establish their true disease status, the difference in accuracy measures between two tests can be evaluated. In practice, however, it is common that only individuals who test positive on at least one screening test are to receive gold standard tests, which are often invasive and cannot be applied to those with negative results on both tests due to ethical reasons. Under such circumstances, estimates of the differences in accuracy measures between two tests cannot be determined, thus the inference problem within this framework is challenging. In this article, using sensitivity and specificity as measures of test accuracy, we show that their difference between two tests is interval-identified, as bounded by estimable sharp bounds. Here, we develop the asymptotic normality for the estimators of the bounds and construct confidence intervals for the difference by utilizing the method for solving inference problem for partially identified parameters. The performance of constructed confidence intervals for the difference and their sharp bounds are evaluated via simulation studies. We also apply the proposed method to the prostate cancer example to compare the accuracy of DRE and PSA.