Kipnis Victor, Subar Amy F, Midthune Douglas, Freedman Laurence S, Ballard-Barbash Rachel, Troiano Richard P, Bingham Sheila, Schoeller Dale A, Schatzkin Arthur, Carroll Raymond J
Biometry Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, MD 20892-7354, USA.
Am J Epidemiol. 2003 Jul 1;158(1):14-21; discussion 22-6. doi: 10.1093/aje/kwg091.
Multiple-day food records or 24-hour dietary recalls (24HRs) are commonly used as "reference" instruments to calibrate food frequency questionnaires (FFQs) and to adjust findings from nutritional epidemiologic studies for measurement error. Correct adjustment requires that the errors in the adopted reference instrument be independent of those in the FFQ and of true intake. The authors report data from the Observing Protein and Energy Nutrition (OPEN) Study, conducted from September 1999 to March 2000, in which valid reference biomarkers for energy (doubly labeled water) and protein (urinary nitrogen), together with a FFQ and 24HR, were observed in 484 healthy volunteers from Montgomery County, Maryland. Accounting for the reference biomarkers, the data suggest that the FFQ leads to severe attenuation in estimated disease relative risks for absolute protein or energy intake (a true relative risk of 2 would appear as 1.1 or smaller). For protein adjusted for energy intake by using either nutrient density or nutrient residuals, the attenuation is less severe (a relative risk of 2 would appear as approximately 1.3), lending weight to the use of energy adjustment. Using the 24HR as a reference instrument can seriously underestimate true attenuation (up to 60% for energy-adjusted protein). Results suggest that the interpretation of findings from FFQ-based epidemiologic studies of diet-disease associations needs to be reevaluated.
多日食物记录或24小时膳食回顾（24HRs）通常被用作“参考”工具，以校准食物频率问卷（FFQs），并针对测量误差调整营养流行病学研究的结果。正确的调整要求所采用的参考工具中的误差独立于FFQ中的误差以及真实摄入量。作者报告了1999年9月至2000年3月进行的观察蛋白质和能量营养（OPEN）研究的数据，在该研究中，对来自马里兰州蒙哥马利县的484名健康志愿者观察了能量（双标水）和蛋白质（尿氮）的有效参考生物标志物，同时还有一份FFQ和24HR。考虑到参考生物标志物，数据表明FFQ会导致绝对蛋白质或能量摄入量的估计疾病相对风险严重衰减（真实相对风险为2时，可能会显示为1.1或更小）。对于通过使用营养素密度或营养素残差对能量摄入量进行调整后的蛋白质，衰减程度较轻（相对风险为2时，可能会显示为约1.3），这支持了能量调整的应用。将24HR用作参考工具可能会严重低估真实的衰减程度（对于能量调整后的蛋白质，低估幅度高达60%）。结果表明，基于FFQ的饮食与疾病关联的流行病学研究结果的解释需要重新评估。
