Friedrich Nele, Alte Dietrich, Völzke Henry, Spilcke-Liss Elisabeth, Lüdemann Jan, Lerch Markus M, Kohlmann Thomas, Nauck Matthias, Wallaschofski Henri
Institute for Community Medicine, Ernst Moritz Arndt University, Walther-Rathenau-Strasse 48, D-17487 Greifswald, Germany.
Growth Horm IGF Res. 2008 Jun;18(3):228-37. doi: 10.1016/j.ghir.2007.09.005. Epub 2007 Nov 7.
Insulin-like growth factor I (IGF-1), which is mostly carried by IGF binding protein 3 (IGFBP-3), mediates endocrine actions of growth hormone and represents an important prognostic factor for systemic diseases. The main objectives of the present study were (1) to calculate age- and sex-specific reference values for serum IGF-1 and IGFBP-3 levels using the Gaussian mean+/-1.96 *standard deviation method and the quantile regression method and (2) to perform a comparison of the results from both statistical methods.
Cross-sectional study (Study of Health in Pomerania). The study population included 2499 men and women aged 20-79 years.
Serum IGF-1 and IGFBP-3 levels were determined by chemiluminescence immunoassays. Linear and quantile regressions were performed to calculate age- and sex-related reference ranges.
Both statistical methods generated different results: The reference ranges based on linear regression identified 43 (1.7%) subjects with serum IGF-1 levels and 99 (4.0%) subjects with serum IGFBP-3 levels outside the reference range. Using quantile regression, 117 (4.7%) or 118 subjects (4.7%) with serum IGF-1 or IGFBP-3 levels outside the range were detected, respectively.
The present study established age- and sex-specific reference ranges for serum IGF-1 and IGFBP-3 levels. Quantile regression should be preferred to calculate reference ranges because a better concordance to original data is possible due to no distribution assumption are required and the robustness against outliers is given.
胰岛素样生长因子I（IGF-1）主要由胰岛素样生长因子结合蛋白3（IGFBP-3）携带，介导生长激素的内分泌作用，是全身性疾病的重要预后因素。本研究的主要目的是：（1）使用高斯均值±1.96×标准差法和分位数回归法计算血清IGF-1和IGFBP-3水平的年龄和性别特异性参考值；（2）对两种统计方法的结果进行比较。
横断面研究（波美拉尼亚健康研究）。研究人群包括2499名年龄在20 - 79岁之间的男性和女性。
采用化学发光免疫分析法测定血清IGF-1和IGFBP-3水平。进行线性回归和分位数回归以计算与年龄和性别相关的参考范围。
两种统计方法得出了不同的结果：基于线性回归的参考范围确定有43名（1.7%）受试者的血清IGF-1水平以及99名（4.0%）受试者的血清IGFBP-3水平超出参考范围。使用分位数回归法，分别检测到117名（4.7%）或118名（4.7%）受试者的血清IGF-1或IGFBP-3水平超出范围。
本研究建立了血清IGF-1和IGFBP-3水平的年龄和性别特异性参考范围。计算参考范围时应优先选择分位数回归法，因为它无需分布假设，对原始数据的拟合度更好，且对异常值具有稳健性。
