Correlation coefficient estimation involving a left censored laboratory assay variable
Correlation coefficient estimation involving a left censored laboratory assay variable
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DOI：
10.1002/sim.901
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发表时间：
2001-10-15
影响因子：
2
通讯作者：
Chuachoowong, R
中科院分区：
文献类型：
--
作者：
Lyles, RH;Fan, DJ;Chuachoowong, R
当评估两个暴露或生物标志物变量之间的相关性时，有时会遇到由于测定检测限而导致其中一个变量的不确定值的问题。在这种情况下，研究人员经常报告在删除涉及不可检测值的配对后计算出的相关系数，或者在用一些小常数代替这些值后计算出的相关系数。这些特别的做法可能会导致真实相关系数的点和置信区间估计值出现偏差。为了解决这个问题，我们考虑两个参数技术估计的相关性存在左删失的变量之一。第一种是最大似然法，第二种是主要由置信区间覆盖的潜在益处激励的多重插补的适应。这两个估计研究减少到标准的皮尔逊相关系数在没有审查的情况下，因此是有效的，在这种措施将是适当的完整的数据的情况下。我们评估这些方法的经验和对比，他们与特设的方法估计宫颈阴道人类免疫缺陷病毒（HIV）病毒载量测量和CD 4+淋巴细胞法院从艾滋病毒阳性妇女参加了在泰国曼谷进行的临床试验之间的相关性。版权所有（C）2001约翰威利父子有限公司
When assessing a correlation between two exposure or biological marker variables, one sometimes encounters the problem of indeterminate values for one of the variables due to an assay detection limit. In this event, investigators often report correlation coefficients computed after removing the pairs involving non-detectable values, or after substituting some small constant for those values. These ad hoc practices can lead to bias in both point and confidence interval estimates of the true correlation coefficient. To address this issue, we consider two parametric techniques for estimating the correlation in the presence of left censoring for one of the variables. The first is a maximum likelihood approach, and the second is an adaptation of multiple imputation motivated primarily by potential benefits in confidence interval coverage. Both of the estimators studied reduce to the standard Pearson's correlation coefficient in the event of no censoring, and hence are valid in cases where this measure would be appropriate for the complete data. We assess these approaches empirically and contrast them with ad hoc methods for estimating the correlation between cervicovaginal human immunodeficiency virus (HIV) viral load measurements and CD4+ lymphocyte courts from HIV positive women enrolled in a clinical trial conducted in Bangkok, Thailand. Copyright (C) 2001 John Wiley & Sons, Ltd.