Sarafin Kurtis, Durazo-Arvizu Ramón, Tian Lu, Phinney Karen W, Tai Susan, Camara Johanna E, Merkel Joyce, Green Evan, Sempos Christopher T, Brooks Stephen P J
Bureau of Nutritional Sciences, Health Canada, Ottawa, Canada;
Department of Public Health Sciences, Loyola University of Chicago Stritch School of Medicine, Chicago, IL;
Am J Clin Nutr. 2015 Nov;102(5):1044-50. doi: 10.3945/ajcn.114.103689. Epub 2015 Sep 30.
The Canadian Health Measures Survey (CHMS) is an ongoing cross-sectional national survey that includes a measure of 25-hydroxyvitamin D [25(OH)D] by immunoassay. For cycles 1 and 2, the collection period occurred approximately every 2 y, with a new sample of ∼5600 individuals.
The goal was to standardize the original 25(OH)D CHMS values in cycles 1 and 2 to the internationally recognized reference measurement procedures (RMPs) developed by the US National Institute for Standards and Technology (NIST) and Ghent University, Belgium.
Standardization was accomplished by using a 2-step procedure. First, serum samples corresponding to the original plasma samples were remeasured by using the currently available immunoassay method. Second, 50 serum samples with known 25(OH)D values assigned by the NIST and Ghent reference method laboratories were measured by using the currently available immunoassay method. The mathematical models for each step-i.e., 1) YCurrent = XOriginal and 2) YNIST-Ghent = XCurrent -were estimated by using Deming regression, and the 2 models were solved to obtain a single equation for converting the "original" values to NIST-Ghent RMP values.
After standardization (cycles 1 and 2 combined), the percentage of Canadians with 25(OH)D values <40 nmol/L increased from 16.4% (original) to 19.4% (standardized), and values <50 nmol/L increased from 29.0% (original) to 36.8% (standardized). The 25(OH)D standardized distributions (cycles 1 and 2 analyzed separately) were similar across age and sex groups; slightly higher values were associated with cycle 2 in the young and old. This finding contrasts with the original data, which indicated that cycle 2 values were lower for all age groups.
The shifts in 25(OH)D distribution brought about by standardization indicate its importance in drawing correct conclusions about potential population deficiencies and insufficiencies and in permitting the comparison of distributions between national surveys.
加拿大健康措施调查（CHMS）是一项正在进行的全国性横断面调查，其中包括通过免疫测定法对25-羟基维生素D [25(OH)D]进行测量。在第1轮和第2轮调查中，采集期大约每2年进行一次，每次抽取约5600名个体作为新样本。
目标是将第1轮和第2轮调查中最初的25(OH)D CHMS值，按照美国国家标准与技术研究院（NIST）和比利时根特大学制定的国际认可的参考测量程序（RMP）进行标准化。
标准化通过两步程序完成。首先，使用当前可用的免疫测定法对与原始血浆样本对应的血清样本进行重新测量。其次，使用当前可用的免疫测定法对50份由NIST和根特参考方法实验室指定了已知25(OH)D值的血清样本进行测量。通过使用Deming回归估计每个步骤的数学模型，即1）Y当前 = X原始 和2）Y NIST - 根特 = X当前 ，并求解这两个模型以获得一个将“原始”值转换为NIST - 根特RMP值的单一方程。
标准化后（第1轮和第2轮合并），25(OH)D值<40 nmol/L的加拿大人比例从16.4%（原始值）增加到19.4%（标准化后），<50 nmol/L的值从29.0%（原始值）增加到36.8%（标准化后）。25(OH)D标准化分布（第1轮和第2轮分别分析）在不同年龄和性别组中相似；在年轻人和老年人中，第2轮的值略高。这一发现与原始数据形成对比，原始数据表明所有年龄组的第2轮值都较低。
标准化带来的25(OH)D分布变化表明，它对于得出关于潜在人群缺乏和不足的正确结论以及允许比较全国性调查之间的分布情况具有重要意义。
