Department of Public Health, Erasmus MC, PO Box 2040 3000, CA Rotterdam, The Netherlands.
Stat Med. 2013 Aug 30;32(19):3332-41. doi: 10.1002/sim.5750. Epub 2013 Jan 31.
Models of cancer screening assume that cancers are detectable by screening before being diagnosed clinically through symptoms. The duration of this preclinical phase is called sojourn time, and it determines how much diagnosis might be advanced in time by the screening test (lead time). In the catch-up time method, mean sojourn time or lead time are estimated as the time needed for cumulative incidence in an unscreened population to catch up with the detection rate (prevalence) at a first screening test. The method has been proposed as a substitute of the prevalence/incidence ratio in the case of prostate cancer where incidence cannot be treated as a constant. A model is proposed to justify this estimator. It is shown that this model is different from classic Markov-type models developed for breast cancer screening. In both models, the catch-up time method results in biased estimates of mean sojourn time.
癌症筛查模型假设在通过症状临床诊断之前，可以通过筛查检测到癌症。这个临床前阶段的持续时间称为逗留时间，它决定了筛查测试（领先时间）可以提前多长时间进行诊断。在追赶时间法中，平均逗留时间或领先时间估计为未筛查人群的累积发病率赶上第一次筛查测试的检出率（患病率）所需的时间。该方法已被提议作为前列腺癌中患病率/发病率比的替代品，因为发病率不能视为常数。提出了一个模型来证明这个估计器。结果表明，该模型与为乳腺癌筛查开发的经典马尔可夫模型不同。在这两种模型中，追赶时间法导致平均逗留时间的估计值存在偏差。
