Hyltoft Petersen Per, Lund Flemming, Fraser Callum G, Sandberg Sverre, Sölétormos György
1 Department of Clinical Biochemistry, Nordsjællands Hospital, University of Copenhagen, Hillerød, Denmark.
2 Norwegian Quality Improvement of Laboratory Examinations (NOKLUS), Haraldsplass Deaconess Hospital, Bergen, Norway.
Ann Clin Biochem. 2018 Sep;55(5):612-615. doi: 10.1177/0004563217752963. Epub 2018 Jan 30.
Background Many clinical decisions are based on comparison of patient results with reference intervals. Therefore, an estimation of the analytical performance specifications for the quality that would be required to allow sharing common reference intervals is needed. The International Federation of Clinical Chemistry (IFCC) recommended a minimum of 120 reference individuals to establish reference intervals. This number implies a certain level of quality, which could then be used for defining analytical performance specifications as the maximum combination of analytical bias and imprecision required for sharing common reference intervals, the aim of this investigation. Methods Two methods were investigated for defining the maximum combination of analytical bias and imprecision that would give the same quality of common reference intervals as the IFCC recommendation. Method 1 is based on a formula for the combination of analytical bias and imprecision and Method 2 is based on the Microsoft Excel formula NORMINV including the fractional probability of reference individuals outside each limit and the Gaussian variables of mean and standard deviation. The combinations of normalized bias and imprecision are illustrated for both methods. The formulae are identical for Gaussian and log-Gaussian distributions. Results Method 2 gives the correct results with a constant percentage of 4.4% for all combinations of bias and imprecision. Conclusion The Microsoft Excel formula NORMINV is useful for the estimation of analytical performance specifications for both Gaussian and log-Gaussian distributions of reference intervals.
背景 许多临床决策是基于将患者结果与参考区间进行比较。因此，需要估计为允许共享通用参考区间所需的质量的分析性能规范。国际临床化学联合会（IFCC）建议至少120名参考个体来建立参考区间。这个数字意味着一定的质量水平，然后可以将其用于定义分析性能规范，即共享通用参考区间所需的分析偏差和不精密度的最大组合，这是本研究的目的。方法 研究了两种方法来定义分析偏差和不精密度的最大组合，该组合将给出与IFCC建议相同质量的通用参考区间。方法1基于分析偏差和不精密度组合的公式，方法2基于Microsoft Excel公式NORMINV，包括超出每个限值的参考个体的分数概率以及均值和标准差的高斯变量。两种方法都展示了标准化偏差和不精密度的组合。对于高斯分布和对数高斯分布，公式是相同的。结果 方法2对于偏差和不精密度的所有组合都给出了4.4%的恒定百分比的正确结果。结论 Microsoft Excel公式NORMINV对于参考区间的高斯分布和对数高斯分布的分析性能规范的估计是有用的。
