Assessing the accuracy of a multiphase diagnosis procedure for dementia
针对痴呆症等多阶段诊断程序，提出一种估计各阶段及整体诊断准确性的方法，并处理验证偏倚问题，通过模拟和实际数据验证其效果。
Multiphase (stage) designs that involve more than two phases are increasingly used by clinicians and psychologists for diagnosis and screening of dementia and many other diseases, e.g. colorectal or breast cancer. The multiphase design is an extension of the commonly used two-phase design, where an inexpensive initial screening test is followed by a gold standard. In a typical three-phase design, the screening test in phase 1 usually has high sensitivity but relatively low specificity. Phase 2 consists of a repeated application of the initial screening test and/or a more confirmatory test and then the gold standard test is used in phase 3. In such designs, both the verification process and the accuracy of each screening test may depend on patients’ characteristics. In addition, multiple-screening tests are correlated and composite decision rules may be used. However, no estimation methods exist for assessing the accuracy of a multiphase diagnosis procedure. To address these problems, we develop a method of estimating the diagnostic accuracy for each individual test and for the whole diagnostic procedure in a multiphase design in the presence of verification bias. Simulation studies are carried out to evaluate the performance of the method proposed and to compare different strategies of combining sequential tests. The method proposed is applied to data from a multiphase study of dementia.