An easy mathematical proof showed that time-dependent bias inevitably leads to biased effect estimation
An easy mathematical proof showed that time-dependent bias inevitably leads to biased effect estimation
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DOI：
10.1016/j.jclinepi.2008.02.008
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发表时间：
2008-12-01
影响因子：
7.2
通讯作者：
Schumacher, Martin
中科院分区：
文献类型：
--
作者：
Beyersmann, Jan;Gastmeier, Petra;Schumacher, Martin
目的：当分析未来暴露状态时，观察开始时已知，会出现时间依赖性偏倚。由于这种偏倚很常见，我们试图确定它是否总是导致偏倚效应估计。研究设计和设置：我们推导了一个简单的数学证明，调查时间依赖性偏倚的性质。我们将一般数学结果应用于重症监护医院感染发生率的前瞻性队列研究数据：在此，我们调查了时间依赖性医院感染状态对重症监护病房住院时间的影响。时间依赖性偏差的性质也说明graphically. Results：偏倚效应估计是一个数学上不可避免的后果的时间依赖性偏差，因为暴露的风险的个人的数量是扭曲的过程中的时间。在时间依赖性暴露的情况下，延长时间，直到研究endpoint.Conclusion：由于时间依赖性偏倚不可避免地导致错误的结果，这是一个主要的问题，它是常见的临床文献。时间依赖性偏倚可以通过适当的基于危险的分析来避免。(C)2008年爱思唯尔公司All rights reserved.
Objective: Time-dependent bias occurs when future exposure status is analyzed as being known with start of observation. As this bias is common, we sought to determine whether it always leads to biased effect estimation. We also sought to determine the direction of the effect bias.Study Design and Setting: We derived an easy mathematical proof investigating the nature of time-dependent bias. We applied the general mathematical result to data from a prospective cohort study on the incidence of hospital infection in intensive care: Here, we investigated the effect of time-dependent hospital infection status on intensive care unit stay. The nature of time-dependent bias was also illustrated graphically.Results: Biased effect estimation is a mathematically inevitable consequence of time-dependent bias, because the number of individuals at risk of exposure is distorted over the course of time. In case of a time-dependent exposure that prolongs time until the study endpoint, the prolonging effect will be overestimated.Conclusion: Because time-dependent bias inevitably leads to erroneous findings, it is a major concern that it is common in the clinical literature. Time-dependent bias can be avoided by proper hazard-based analyses. (C) 2008 Elsevier Inc. All rights reserved.