Measurement error and results from analytic epidemiology: Dietary fat and breast cancer
Measurement error and results from analytic epidemiology: Dietary fat and breast cancer
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DOI：
10.1093/jnci/88.23.1738
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发表时间：
1996-12-04
期刊：
影响因子：
--
通讯作者：
Prentice, RL
中科院分区：
文献类型：
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作者：
Prentice, RL
背景：国际相关分析表明，脂肪摄入与乳腺癌发病率之间存在强烈的正相关关系，尤其是绝经后妇女。然而，病例对照研究表明两者之间存在较弱的关联，而最近的一项合并队列分析报告几乎没有证据表明两者之间存在关联。研究结果之间的差异可能是由于研究人群的差异、总能量摄入对照的差异、病例对照研究中的回忆偏差以及饮食测量误差偏差。现有的测量误差模型要么假设用于验证饮食自我报告工具的样本数据没有测量误差，要么假设任何此类误差都独立于真实的饮食暴露和其他研究对象特征。然而，越来越多的证据表明，随着体脂百分比的增加，总能量，大概包括总脂肪和脂肪能量百分比都被低估了。目的：介绍一种宽松的饮食测量模型，该模型允许所有测量误差参数依赖于体重指数（体重以公斤为单位除以身高以米为单位的平方），并纳入一个随机的低报量，适用于每个饮食自我报告工具。该模型应用于国际相关分析的结果，以确定膳食脂肪与绝经后乳腺癌之间的不同关联是否可以通过饮食评估中的测量误差来解释。方法：利用4天饮食记录（4DFRs）中的总脂肪摄入量和脂肪能量百分比数据以及原始妇女健康试验（Women’s Health Trial）中的食物频率问卷（FFQs）建立宽松测量模型。本试验是一项随机、对照、低脂饮食干预的可行性研究，于1985年至1988年在辛辛那提（俄亥俄州）、休斯顿（得克萨斯州）和西雅图（华盛顿州）进行，共有303名妇女（干预184名，对照组119名），年龄在45-69岁之间。松弛模型用于将国际相关性分析的结果投射到4DFR和FFQ脂肪摄入类别上。结果和结论：如果完全忽略饮食评估中的测量误差，基于国际数据的乳腺癌预测相对风险（rr）在总脂肪摄入量的百分位数之间存在很大差异。90%脂肪摄入百分位数与10%脂肪摄入百分位数的预测RR在4DFR为3.08，在FFQ为4.00。如果测量误差的随机（即噪声）方面得到确认，则相同比较的预测RR与4DFR和FFQ分别减少到1.54和1.42。如果测量误差的系统方面和噪声方面都得到确认，那么任何一种仪器的预测RR都减少到约1.10。对测量误差的承认也导致预测的相对危险度约为1.10，对于90%百分比的脂肪能量和10%百分比的脂肪能量，使用任何一种饮食工具。含义：由于测量误差偏差，饮食自我报告工具可能不足以用于膳食脂肪和疾病风险的分析流行病学研究。
Background: International correlational analyses have suggested a strong positive association between fat consumption and breast cancer incidence, especially among postmenopausal women. However, case-control studies have been taken to indicate a weaker association, and a recent, pooled cohort analysis reported little evidence of an association. Differences among study results could be due to differences in the populations studied, differences in the control for total energy intake, recall bias in the case-control studies, and dietary measurement error biases. Existing measurement error models assume either that the sample data used to validate dietary self-report instruments are without measurement error or that any such error is independent of both the true dietary exposure and other study subject characteristics. However, growing evidence indicates that total energy and, presumably, both total fat and percent energy from fat are increasingly underreported as percent body fat increases. Purpose: A relaxed dietary measurement model is introduced that allows all measurement error parameters to depend on body mass index (weight in kilograms divided by the square of height in meters) and incorporates a random underreporting quantity that applies to each dietary self-report instrument. The model was applied to results from international correlational analyses to determine whether the differing associations between dietary fat and postmenopausal breast cancer can be explained by measurement errors in dietary assessment. Methods: The relaxed measurement model was developed by use of data on total fat intake and percent energy from fat from 4-day food records (4DFRs) and food-frequency questionnaires (FFQs) from the original Women's Health Trial. This trial was a randomized, controlled, feasibility study of a low-fat dietary intervention carried out from 1985 through 1988 in Cincinnati (OH), Houston (TX), and Seattle (WA) among 303 women (184 intervention and 119 control) who were 45-69 pears of age. The relaxed model was used to project results from the international correlational analyses onto 4DFR and FFQ fat-intake categories. Results and Conclusions: If measurement errors in dietary assessment are overlooked entirely, the projected relative risks (RRs) for breast cancer based on the international data vary substantially across percentiles of total fat intake. The projected RR for the 90% versus the 10% fat-intake percentile is 3.08 with the 4DFR and 4.00 with the FFQ. If random (i.e., noise) aspects of measurement error are acknowledged, the projected RR for the same comparison is reduced to 1.54 with the 4DFR and 1.42 with the FFQ. If both systematic and noise aspects of measurement error are acknowledged, the projected RR is reduced to about 1.10 with either instrument. Acknowledgment of measurement error also leads to a projected RR of about 1.10 for the 90% versus the 10% percentile of percent energy from fat with either dietary instrument. Implications: Dietary self-report instruments may be inadequate for analytic epidemiologic studies of dietary fat and disease risk because of measurement error biases.