Parvin Curtis A, Robbins Sanford
Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO, USA.
Clin Chem. 2007 Apr;53(4):575-80. doi: 10.1373/clinchem.2006.083311. Epub 2007 Feb 22.
Although minimum regulatory standards exist for determining QC testing frequency, decisions regarding when and how to run QC samples are not standardized. Most QC testing strategies test control samples at fixed time intervals, often placing the samples in the same position on an instrument during subsequent QC events and leaving large gaps of time when control samples are never run, yet patient samples are being tested.
Mathematical derivations and computer simulation were used to determine the expected waiting time between an out-of-control condition and the next scheduled QC test for various QC testing strategies that use fixed or random intervals between QC tests.
Scheduling QC tests at fixed intervals yields an average time between the occurrence of an out-of-control error condition and the next scheduled QC test that is equal to half of the fixed time interval. This performance was the best among the QC scheduling strategies investigated. Near-optimal performance, however, was achieved by randomly selecting time intervals between QC events centered on the desired expected interval length, a method that provides variation in QC testing times throughout the day.
If the goal is to vary QC testing times throughout the day while maintaining the shortest expected length of time between error conditions and the next scheduled QC test, then a near-optimal QC scheduling strategy combines randomly selected time intervals centered on the desired length of time between QC events with fixed time intervals.
尽管存在确定质量控制（QC）测试频率的最低监管标准，但关于何时以及如何运行QC样本的决策并未标准化。大多数QC测试策略在固定的时间间隔对对照样本进行测试，在后续的QC事件中，通常将样本放置在仪器上的相同位置，并且在从不运行对照样本但却在测试患者样本时留下大量的时间间隔。
使用数学推导和计算机模拟来确定对于各种使用固定或随机QC测试间隔的QC测试策略，失控状态与下一次预定QC测试之间的预期等待时间。
以固定间隔安排QC测试会使失控错误状态出现与下一次预定QC测试之间的平均时间等于固定时间间隔的一半。在研究的QC调度策略中，这种性能是最佳的。然而，通过围绕所需的预期间隔长度随机选择QC事件之间的时间间隔可实现接近最优的性能，这种方法可使全天的QC测试时间有所变化。
如果目标是在全天改变QC测试时间，同时保持错误状态与下一次预定QC测试之间的最短预期时间长度，那么一种接近最优的QC调度策略是将围绕所需的QC事件间隔长度随机选择的时间间隔与固定时间间隔相结合。
