Toenail trace element levels as biomarkers: reproducibility over a 6-year period.
Toenail trace element levels as biomarkers: reproducibility over a 6-year period.
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1993-09
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通讯作者：
Miriam;Garland;J. Steven;Morris;Bernard;-A.;Rosner;Meir;J. Stampfer;Victoria;L. Spate;Connie;Baskett;Walter;-C.;Willett;David;J. Hunter
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作者：
Miriam;Garland;J. Steven;Morris;Bernard;-A.;Rosner;Meir;J. Stampfer;Victoria;L. Spate;Connie;Baskett;Walter;-C.;Willett;David;J. Hunter
我们通过比较1982-1983年和1988年收集的127名美国妇女的配对样本中的水平，评估了6年时间里脚趾甲中测量的16种微量元素的重复性。趾甲中硒和砷(均可反映这些元素的摄入量)的重现性的Spearman相关系数分别为0.48和0.54。其他元素的相关系数在0.26(铜)到0.58(锌)之间。在癌症和其他慢性疾病的流行病学研究中，在利用生物标记物评估暴露时，暴露中的随机人内变异性导致暴露与疾病之间联系的衡量标准的减弱。我们从一项假设性病例对照研究中论证了这种变异性对优势比的影响。对于真实的优势比3.0(比较暴露的最高五分位数和其余四分位数)，在这项研究中显示的人内变异程度存在的情况下观察到的优势比是脚趾甲砷水平的2.15和脚趾甲铜水平的1.67。脚趾甲中某些微量元素的浓度是暴露的有用生物标志物，其中单个样本被认为代表长期暴露。然而，关联性度量可能会出现显著的衰减。
We assessed the reproducibility over a 6-year period of 16 trace elements measured in toenails by comparing levels in paired specimens collected in 1982-1983 and 1988 from 127 women in the United States. The Spearman correlation coefficients for the reproducibility of toenail levels of selenium and arsenic (both known to reflect intake of these elements) were 0.48 and 0.54. Correlations for other elements ranged from 0.26 (copper) to 0.58 (zinc). In utilizing biomarkers to assess exposure in epidemiological studies of cancer and other chronic disease, random within-person variability in exposure leads to attenuation of measures of association between exposure and disease. We demonstrate the effect of such variability on odds ratios from a hypothetical case-control study. For a true odds ratio of 3.0 (for a comparison of the highest quintile versus the remaining 4 quintiles of exposure) the odds ratios which would be observed in the presence of the degree of within-person variability demonstrated in this study were 2.15 for toenail arsenic and 1.67 for toenail copper levels. Toenail concentrations of certain trace elements are useful biomarkers of exposure in which a single sample is assumed to represent long-term exposure. However, substantial attenuation in measures of association may occur.