Chiecchio A, Malvano R
Servizio di Fisica Sanitaria, Ospedale Mauriziano, Torino, Italy.
Eur J Clin Chem Clin Biochem. 1996 May;34(5):423-30. doi: 10.1515/cclm.1996.34.5.423.
As an alternative to the oversimplified error schemes currently adopted in establishing quality control (QC) strategies, a complex model was assumed implying (a) the distribution of errors (critical error is regarded as a value discriminating between "effective errors" to be detected and "subcritical errors" which do not interfere with the medical decision whose detection is considered as a false-reject signal), and (b) the possibility of simultaneous losses of precision and accuracy. The control data recorded for digoxin radioimmunoassay over a one-year period were used for (1) deriving the probability density functions of random and systematic errors, through a within-run across-level normalisation procedure; (2) obtaining the functional relationships between the critical random or systematic error and the QC performance statistics (sensitivity, specificity, predictive value), weighted for the error prevalences, through integration of the probability density functions and the power functions associated with an exemplifying control rule; and (3) describing the functions which correlate the corrected performance statistics with the allowable error (whose individual values account for all possible combinations of critical random errors and critical systematic errors), by extending to the tridimensional space the above procedures. Analysis of the resulting data shows that it is necessary to revise the criteria for the choice and optimisation of QC schemes.
作为目前在建立质量控制（QC）策略时采用的过度简化误差方案的替代方案，假设了一个复杂模型，该模型意味着：（a）误差分布（临界误差被视为区分要检测的“有效误差”和不干扰医学决策的“亚临界误差”的值，后者的检测被视为假拒收信号），以及（b）精度和准确性同时损失的可能性。使用在一年时间内记录的地高辛放射免疫分析的控制数据用于：（1）通过批内跨水平归一化程序推导随机误差和系统误差的概率密度函数；（2）通过对概率密度函数和与示例控制规则相关的幂函数进行积分，获得临界随机或系统误差与QC性能统计量（灵敏度、特异性、预测值）之间的函数关系，并根据误差发生率进行加权；以及（3）通过将上述程序扩展到三维空间，描述将校正后的性能统计量与允许误差相关联的函数（其单个值考虑了临界随机误差和临界系统误差的所有可能组合）。对所得数据的分析表明，有必要修订QC方案的选择和优化标准。
