Limitations of “Default” to One-size-fits all QC
According to the collective opinion paper on findings of the 2010 convocation of experts on laboratory quality “accurate testing and short turn around times contribute to patient care.”2 Nonetheless, the current economic climate can force cost saving measures on laboratories that may compromise accurate testing and short turn around times. For example, the pressure to cut costs may cause default to the regulatory minimum frequency for running QC materials. This default can in turn open a window of vulnerability whenever patient results are reported between the evaluation of QC materials. For more information on the extent of the window of vulnerability see the related article Expected Number of Patients Compromised by Failure.
Since the expectation is that on average half the number of patient specimens tested between QC evaluations will be affected in the event of an undetected test system failure3 , the question becomes how often should QC materials be run? Typically, analyzer performance is verified with QC materials before running patient samples. But consider the situation of a systematic failure prior to the next QC event. Can the laboratory afford the risk of reporting patient results before QC materials have been run again and the results reviewed? In the event of an unacceptable analytical run, can the laboratory afford the delay, direct and overhead costs of repeating patient samples? Furthermore, there are some labile analytes that cannot be repeated. Surely, patient samples should be bracketed by QC materials and the QC data evaluated before reporting patient results. Perhaps then, the interval to be bracketed by running QC materials is the desired turnaround time rather than a minimum regulatory requirement.
2 Cooper, et al, “Collective opinion paper on findings of the 2010 convocation of experts on laboratory quality.” Clinical Chemistry Laboratory Medicine. 2011; 49(5):793-802.
3 Parvin, C.A., Yundt-Pacheco, J., Williams, M. “Designing a quality control strategy: In the modern laboratory three questions must be answered,” ADVANCE for Administrators of the Laboratory 2011;(5):53-54.