Obuchowski Nancy A, Zhou Xiao-Hua
Department of Biostatistics and Epidemiology, Wb4, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Biostatistics. 2002 Dec;3(4):477-92. doi: 10.1093/biostatistics/3.4.477.
Prospective studies of diagnostic test accuracy have important advantages over retrospective designs. Yet, when the disease being detected by the diagnostic test(s) has a low prevalence rate, a prospective design can require an enormous sample of patients. We consider two strategies to reduce the costs of prospective studies of binary diagnostic tests: stratification and two-phase sampling. Utilizing neither, one, or both of these strategies provides us with four study design options: (1) the conventional design involving a simple random sample (SRS) of patients from the clinical population; (2) a stratified design where patients from higher-prevalence subpopulations are more heavily sampled; (3) a simple two-phase design using a SRS in the first phase and selection for the second phase based on the test results from the first; and (4) a two-phase design with stratification in the first phase. We describe estimators for sensitivity and specificity and their variances for each design, along with sample size estimation. We offer some recommendations for choosing among the various designs. We illustrate the study designs with two examples.
诊断试验准确性的前瞻性研究比回顾性设计具有重要优势。然而，当诊断试验所检测的疾病患病率较低时，前瞻性设计可能需要大量的患者样本。我们考虑两种降低二元诊断试验前瞻性研究成本的策略：分层和两阶段抽样。不使用、使用其中一种或两种策略为我们提供了四种研究设计选项：（1）传统设计，涉及从临床人群中简单随机抽取患者样本；（2）分层设计，对患病率较高的亚人群中的患者进行更多抽样；（3）简单的两阶段设计，在第一阶段使用简单随机抽样，并根据第一阶段的检测结果选择第二阶段的样本；（4）在第一阶段进行分层的两阶段设计。我们描述了每种设计的灵敏度和特异性估计量及其方差，以及样本量估计。我们为在各种设计中进行选择提供了一些建议。我们用两个例子说明了这些研究设计。
